Optimization of 3D Printing Conditions for the Development of Gummies

from Watermelon Rind Waste

A project report submitted for the partial fulfilment of the requirements for the degree of

Bachelor of Technology
in
Food Technology

By

Anandhakeerthy M (2021U1007)
Dhanaselvam K R (2021U1017)

National Institute of Food Technology,

Entrepreneurship and Management, Thanjavur (NIFTEM-T)
(An Institute of National Importance under MoFPI, Government of India)
Pudukkottai Road, Thanjavur – 613005
2025

1
 CERTIFICATE

This is to certify that the project entitled “Optimization of 3D Printing Conditions for the

Development of Gummies from Watermelon Rind Waste” submitted in partial fulfillment

of the requirements for the award of Degree of Bachelor of Technology in Food Technology

to National Institute of Food Technology, Entrepreneurship and Management,

Thanjavur (NIFTEM-T), is a record of bonafide project work carried out at NIFTEM-T by

Anandha Keerthy M (2021U1007) and Dhanaselvam K R (2021U1017) under my

supervision and guidance.

Dr. Jeyan Arthur Moses Dr.M.Loganathan

Project Guide Dean (Academics)

Date:
Place: Thanjavur

2
3
4
 ACKNOWLEDGEMENT

This thesis journey has been a rewarding experience, and we would like to express

our sincere gratitude to those who have supported us along the way. At this juncture, it is our

pleasure to glance back and recall the path we traveled during the day of hard work,

optimism, and perseverance whereby we were accompanied, supported, and guided by many

people. It's our heart's turn to express our deepest sense of gratitude to all those who directly

or indirectly helped us in this endeavor.

First of all, we would like to express our deepest sense of gratitude to our mentor,

Dr. Jeyan Arthur Moses, Assistant Professor, Computational Modeling and Nanoscale

Processing Unit, Department of Food Process Engineering, NIFTEM-T for his thoughtful

guidance, patience, motivation, invaluable advice, immense help, and constant support

offered throughout our project work.

We would like to place our gratitude towards Dr. V. Palanimuthu, Director for

providing us a great platform with all essential facilities for the completion of our work.

We are very grateful to Dr. M. Loganthan, Dean, Academics for his consistent

support and motivation during our project.

We would also like to acknowledge the immense support provided by

Dr. R. Paranthaman, Cheif Technical Officer, Computational Modeling and Nanoscale

Processing Unit, NIFTEM-T.

We are very grateful to all CMNSPU Deparentmt members and we are indebted to

our dearest seniors, Dr. V. Ravikrishnan, Mr. P. Santhoshkumar for providing practical

guidance through the entire project and rectified all the errors we made in the lab and thesis

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work. We sincerely extend our gratitude to him for making this project successful and more

informative.

We would extend our heartfelt gratitude to our beloved lab seniors, Mr.

Manibharathi, Dr. Dhanya, Ms. Mamtha, Ms. Valarmathi, Ms. Praveena, Ms. Sruti Chandra,

Ms. Keerthi, Mrs. Anuja, Ms. Neeta, Mr. Ashwin, Mr. Naveen, and all our batchmates for

their help, patience, encouragement, and motivation throughout our research work.

Last but not least, we extend our heartfelt gratitude to our parents, whose unwavering

support, encouragement, and love have been the cornerstone of our academic journey. Their

sacrifices, guidance, and belief in our abilities have fueled our determination to pursue this

thesis and have been instrumental in shaping us.

Lastly, we extend our thanks to all those who have directly or indirectly contributed to

this endeavor, whether through their encouragement, insights, or assistance. Your support has

been indispensable, and we are deeply grateful for your contribution to this academic

endeavor.

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Anandhakeerthy. M Dhanaselvam. K. R

Table of contents
Chapter Title Page no.
no.
1. Introduction

1.1 3D printing

1.2 3D food printing

1.3 Waste valorization

1.4 Objectives

2. Review of literature

2.1 3D printing

2.2 3D food printing

2.2.1 Extrusion-based 3D food printing

2.2.2 Selective laser sintering based 3D food

printing
2.2.3 Binder jetting based 3D food printing

2.2.4 Inkjet printing

2.3 Applications of 3D food printing

2.3.1 Customization of Nutrition

2.3.2 Culinary arts

2.3.3 Globalization of Printed Foods

2.3.4 Space foods

2.3.5 Health and medical applications

2.3.6 Sustainability and resource efficiency

2.4 Circular economy

2.5 Functional food development from waste

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 2.6 Watermelon

2.7 Food waste valorization

2.8 Gummies
3. Materials and methods

3.1 Preparation of material supply

3.2 Assessment of Quality

3.2.1 Water activity and color

3.2.2 Texture
3.2.3 Rheology
3.2.4 Thermal behavior

3.3 3D printing and optimization

3.4 Sensory evaluation
3.5 Statistical analysis

3.6 Proximate analysis

3.6.1 Moisture content

3.6.2 Protein content

3.6.3 Fat content

3.6.4 Total ash

3.6.5 Crude Fiber

3.6.6 Carbohydrate

3.6.7 Energy

4. Results and discussion

4.1 Material supply characterization

4.1.1 Water activity

4.1.2 Color

4.1.3 Texture

4.1.4 Rheology

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 4.1.5 Thermal behaviour

4.2 Optimization of hot extrusion 3D printing

conditions

4.3 Quality of 3D printed gummies

4.4 Sensory evaluation

4.4.1 Visual sensory

4.4.2 Product sensory

4.5 Proximate analysis

4.5.1 Moisture content

4.5.2 Protein content

4.5.3 Fat content

4.5.4 Total ash

4.5.5 Crude Fiber

4.5.6 Carbohydrate and energy

5. Summary and conclusion

References

6. Publications

7. References

8. Appendices

LIST OF TABLES

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 Tables Title Page
no.
4.1.1 Water activity of material supplies

4.1.2 Color of material supplies

4.1.3 (a) Textural attributes of the material supplies

4.1.3 (b) Textural attributes of the material supplies

4.1.4 Rheological behavior of the material supplies

4.1.5 Thermal behavior of material supplies

4.2 Optimization of hot-extrusion 3D printing condition of the

material supplies
4.5.1 Moisture content of samples

4.5.2 Protein content of samples

4.5.3 Fat content of samples

4.5.4 Crude fiber of samples

4.5.5 Total ash content of samples

4.5.6 Carbohydrate content of samples

LIST OF FIGURES
Figures Title Page
no.
1 Publication trends of 3D printing, and waste valorization

2 Process of extrusion-based 3D food printing

3 Watermelon rind slices

4 Blanched watermelon rind

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5 Ground rind puree

6(a) Multi-CARK 3D food printer

6(b) Selected 3D geometry for this study (Twisted hexagon)

7 Shear ramp curve for the material supplies

8 Visual sensory profiles of 3D printed gummies

9 Sensory profile comparison of commercial and 3D printed gummies

10 Dried rind paste in oven tray

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 Abstract
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 ABSTRACT
Optimization of 3D Printing Conditions for the Development of Gummies from

Watermelon Rind Waste

BY

Anandhakeerthy. M

Dhanaselvam. K.R

Degree : Bachelor of Technology (Food Technology)

Project guide : Dr. Jeyan A. Moses

Assistant Professor

Computational Modeling and Nanoscale Processing Unit

National Institute of Food Technology, Entrepreneurship and

Management,Thanjavur- 613005, Tamil Nadu, India

2025

This initiative focuses on finessing 3D food printing to repurpose waste byproduct of fruit

processing. In this study, hot extrusion 3D printing conditions were specially optimised to

produce vegan gummy from watermelon rind. Watermelon rind puree, sugar, and various

concentrations of pectin (0%, 5%, 10%, 15% and 20% w/w) were mixed together to

fabricate printables gummies. To relate such material qualities to printability, material

supply processing was characterised through textural, rheological and thermal analysis. The

printing factors analyzed included speed (600, 800, and 1000 mm/min), nozzle diameter

(0.6, 0.84, and 1.22 mm), and temperature (60, 80, and 100 °C). The best formulation (10%

high-methoxyl pectin) exhibited improved print precision, at a nozzle diameter of 0.84 mm,

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 80 °C and 800 mm/min. In sensory evaluation, consumers favoured 3D-printed gummies

over non-3D-printed products. This research demonstrates the potential of 3D printing

processes to contribute to sustainable waste valorization and upcycling in accordance with

United Nations Sustainable Development Goals. The application of this profitability model

demonstrates a possible restructuring of the value chain through agricultural byproducts

and waste that has long been thought of as waste, while at the same time reaping the

customization benefits of 3D printing to diversify products and also find consumers willing

to taste the products.

Keywords: Fruit waste; watermelon rind; hot extrusion printing; 3D food printing; waste

valorization; upcycling.

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 Introduction
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 CHAPTER I

1.INTRODUCTION

1.1. 3D printing

Three-dimensional printing, or additive manufacturing, is a process for making three-

dimensional objects from digital files. This includes the 3D printing as they build proxies

using thin layers of materials like plastic, metal, or resin and applying those layers until they

create an object that they can print. You start with a 3D model using computer-aided design

(CAD) software. Once the design is done, we convert the model into a file that is readable by

the 3D printer. It does this, layer by layer, by melting or hardening material to build the

object, meaning it works much like traditional printing. This technology has become

prevalent in industries such as healthcare, aerospace, automotive and manufacturing. It

provides benefits including rapid prototyping, customized designs, and minimized material

waste compared to traditional production. 3D printing has revolutionized product

development by allowing for more efficient, cost-effective production. It became popular

among hobbyists and creators who could create personalized products. With its

advancement, 3D printing even has the ability to venture into bioprinting and construction.

1.2. 3D food printing

3D food printing is a technique by which a three-dimensional object is produced by

sequentially depositing layer upon layer of food materials like dough, flour, and chocolate.

There are several techniques of 3D food printing classified based on their specific role in the

development of 3D food products, and among them, extrusion-based 3D food printing is the

most extensively used technique in food processing technology. Some benefits of this

approach are its flexibility in varied nutrient content, shapes, colours, and size, tailored to

customer demands. While food industry commercialization of 3D food printing remains

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pending, several pilot-scale and bench-top printers were sold with being adopted by

restaurants in countries like UAE and US. However, 3D chocolate printers have attracted

huge interest and consumer appeal.

1.3. Waste valorization in 3D food printing

It has been estimated that the global food industry generates an enormous amount of

fruit waste in the form of peels, seeds, and cores, typically discarded as by-products to

landfills. It not only results in environmental pollution but also wastes valuable resources

from fruitful items, which could have otherwise been put to use. The wastes resulting from

the process of processing fruits for consumption are very often overlooked. They are a source

of many bioactive compounds that contain antioxidants, dietary fiber, and phenolics. All

these are believed to offer some potential health benefits like better digestion, immunity

boosters, and anti-inflammatory effects.

Recent studies have been based on the fruit waste valorization concept due to

increasing environmental concerns and the demand to use more environmentally friendly

practices. Fruit waste valorization is a technique of finding new ways of reutilizing discarded

byproducts, which can be transformed into valuable products like natural preservatives,

nutraceuticals, or even biofuels. In this way, fruit waste utilization decreases the total quantity

of waste, lowers environmental pollution, and promotes a sustainable economy. Fruit waste

valorization is not only the reduction of waste but also a recovery of valuable resources for

the better use of food, pharmaceuticals, and cosmetics than possibly being discarded.

An emerging promising technology, 3D food printing can further add more value to

fruit waste. Fuelled by the achievements made in robotics, 3D printing is considered one of

the transformative technologies across various sectors, from automobile and medicine to food

manufacturing. This digital process permits the creation of complex objects, layer upon layer,

with materials such as metals through to biomaterials.

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 In the food design world, 3D food printing presents a very innovative approach; one

can get into the business of designing a shape, color, flavor, and even a customized

nutritional composition. The idea of using waste fruits in producing 3D printing inks that

contain fruit powders, fibers, or extracts allows one to create sustainable, innovative, and

nutritionally improved foodstuffs with excellent sensory properties. Additionally, the

developments in veganism and plant-based diets in the world have raised the demand for

innovative and sustainable food products that are free of animal-derived ingredients. The aim

of this study was to optimize the printing conditions of 3D-printed vegan product out of fruit

waste.

Fig 1. Publication trends of 3D printing, and waste valorization

1.4. Objectives

 Preparation and characterisation of watermelon rind based 3D printing material

supplie(s)

 Optimization of hot extrusion food 3D printing conditions for the production of

gummies

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 Evaluating sensory and post-printing characteristics of 3D printed gummies

Review of Literature

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 CHAPTER II

2.REVIEW OF LITERATURE

2.1. 3D printing

3D printing, or additive manufacturing (AM), is the process of creating physical

objects from geometric designs by sequentially adding material (Shahrubudin et al., 2019).

The first person to commercialize this technology was Charles Hull in the 1980s (Holzmann

et al., 2017). Today, 3D printing is applied in different fields, such as the manufacture of

artificial heart pumps, jewelry, 3D printed corneas, PGA rocket engines, a steel bridge in

Amsterdam, and products for the aviation and food industries (Shahrubudin et al., 2019). This

technology originated from layer-by-layer fabrication of 3D structures based on computer-

aided design (CAD) drawings (Moiduddin et al., 2019). Materials such as conventional

thermoplastics, ceramics, graphene-based materials, and metals can now be printed using 3D

printing technology (Wang et al., 2019).

There are several 3D printing technologies developed for different functions for required

applictaions.

Binder jetting is a form of 3D printing whereby the liquid binder is used to bind the powder

particles together into layers (Bai et al., 2017). Such large-volume products are made of

materials such as sand, metals, and ceramics. Some may require no extra processing. With

such a straightforward, fast, and inexpensive method, large objects can be printed.

Directed energy deposition is a complex printing process that uses direct repair or adding of

material to the existing components (Moiduddin et al., 2019). It allows for direct control of

the grain structure and therefore yields high quality. With DED, the nozzle is not fixed like in

material extrusion and the head can move in more than one direction. While DED can be

applied to ceramics and polymers, it is largely applied to metals and metal-based hybrids,

both in wire or powder form. Examples of such technologies include laser deposition and

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LENS. Laser deposition, a rapidly emerging technology, is used in the production or repair of

parts from millimeters to meters and is gaining popularity among various industries like

aerospace, transportation, tooling, and oil and gas. Its scalability and versatility make it

highly sought after (Lang et al., 2023). LENS uses thermal energy during the casting by

melting in the process and finishes the part afterwards.

Material extrusion-based 3D printing technology allows for multi-material and multi-color

printing of plastics, food, or living cells (Mohammed, 2016). This widely used process is

cost-effective and capable of creating fully functional parts (Moiduddin et al., 2019). Fused

Deposition Modeling (FDM), developed in the early 1990s, is the first material extrusion

system, primarily using polymers as the main material (Stansbury & Idacavage, 2016).

Material jetting is a type of 3D printing in which droplets of build material are selectively

deposited, layer by layer. Here, a printhead dispenses droplets of a photosensitive material

that hardens under UV light to form the part (Silbernagel et al., 2019). Material jetting

produces parts with a smooth surface finish and high dimensional accuracy. It also supports

multi-material printing and can work with a wide variety of materials, including polymers,

ceramics, composites, biologicals, and hybrids (Moiduddin et al., 2019).

Powder bed fusion process includes techniques like electron beam melting (EBM), selective

laser sintering (SLS), and selective heat sintering (SHS), all of which use an electron beam or

laser to melt or fuse material powders. These methods work with materials such as metals,

ceramics, polymers, composites, and hybrids. SLS, developed by Carl Deckard in 1987, is a

key example of powder-based 3D printing. It offers fast speed, high accuracy, and various

surface finishes (Tiwari et al., 2015). SLS uses a high-power laser to sinter polymer powders

into 3D objects, while SHS employs a thermal print head to melt thermoplastic powders.

EBM, on the other hand, uses an energy source to heat and melt materials (Ventola, 2014).

21
Sheet lamination is a 3D printing process where layers of material are bonded together to

create parts (Silbernagel et al., 2018). Technologies like Laminated Object Manufacturing

(LOM) and Ultrasound Additive Manufacturing (UAM) utilize this process (Moiduddin et

al., 2019). Advantages of sheet lamination include full-color printing, low cost, ease of

material handling, and the ability to recycle excess material. LOM can produce complex

geometrical parts at a lower fabrication cost and reduced operational time

(Vijayavenkataraman et al., 2017). UAM, an innovative process, uses sound to merge metal

layers from foil stock.

Vat Photopolymerization is a 3D printing technique that cures photo-reactive polymers using

UV light, laser, or other light sources (Low et al., 2017). Technologies like Stereolithography

(SLA) and Digital Light Processing (DLP) use this method. SLA relies on photo initiators

and exposure conditions, while DLP uses an arc lamp and LCD panel for faster printing. The

key parameters are exposure time, wavelength, and power. This technique is ideal for

creating high-quality, detailed parts with excellent surface finishes (Novakov et al., 2017).

2.2. 3D food printing

3D food printing involves the extrusion of material layer on top of a layer according

to a preconceived digital design (Additive Manufacturing Applications within Food Industry:

An Actual Overview and Future Opportunities, n.d.). The specific method applied in building

structures is dependent on the type of 3D food printing. The quality and accuracy of printed

objects are highly influenced by the properties of the materials, processing conditions, as well

as post-processing treatments. The common techniques among the above include the

following: the four most extensively used 3D printing methods in food industrial

applications, extrusion-based printing, SLS, binder jetting, and inkjet printing.

2.2.1. Extrusion-based 3D food printing

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 The extrusion-based printing, which is also called fused deposition modeling (FDM),

was initially presented for making plastic products (Ahn et al., 2002).The melted or paste-like

slurry, during the process of extrusion printing, continuously flows out of a nozzle and welds

the previously formed layers together once it cools. Using this kind of extrusion-based

printing is not only good for chocolate printing but also useful for printing dough, mashed

potatoes, cheese, and even meat paste (Lipton & Lipson, 2016)(Yang et al., 2019).However,

though the technology has successfully deposited various types of soft materials, there are

issues in terms of achieving detailed shapes due to their tendency to warp or deform. Due to

their intrinsic instability, support structures in many instances are necessary during the

extrusion process to sustain the desired geometry in the resulting product. It would therefore

end up upholding the soft material during printing, hence its need for the application of such

supports. However, at the final stage, these supporting elements have to be manually removed

in order to achieve the final desired product. This process is very time-consuming and thus

decreases the printing speed as well as increases the cost of material (von Hasseln, 2017)

(Gale et al., 2015). Since it is an extrusion process it is vital to understand the materials

properties like rheological properties, gelling nature, thermal behavior, and glass transition

temperature. Then come the other factors of considerables, processing factors like nozzle

height, nozzle diameter extrusion speed, and post processing treatments such as baking,

drying, frying, and steaming etc.

Extrusion 3D food printing utilizes three main extrusion mechanisms, namely screw-based

extrusion, air pressure-based extrusion, and syringe-based extrusion. The screw-based

extrusion feeds the food materials into a feeder and pushes them up through the nozzle tip as

a result of the screw's movement. This methodology allows for the continuous feeding of

material into the hopper, thus not having to stop mid-print. However, screw-based extrusion

is less effective for highly viscous foods with significant mechanical strength. As a result, the

23
printed structures may lack sufficient mechanical integrity to support subsequent layers,

leading to compression deformation and reduced resolution (Z. Liu et al., 2017).Air pressure-

based extrusion operates by using compressed air to push food materials toward the nozzle,

making it well-suited for printing liquids or low-viscosity substances (Sun et al., 2018). On

the other hand, syringe-based extrusion is designed to handle highly viscous food materials

that have higher mechanical strength so as to be able to form more complex 3D structures

with high accuracy.

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 Fig 2. Process of extrusion-based 3D food printing

Nachal, N., Moses, J.A., Karthik, P. et al. Applications of 3D Printing in Food Processing. Food Eng Rev 11,
123–141 (2019

2.2.2. Selective laser sintering based 3D food printing

Selective laser sintering (SLS) is one of the techniques of 3D printing where a high-

powered laser is used to fuse the powdered particles in a layer by layer manner and thus form

a solid structure. The laser scans and bonds the material on each layer's surface in a pattern

that shapes the design. The powder bed is then lowered and a fresh layer of powder is spread

over it after each layer is processed. This cycle is repeated until the complete structure is

built. Any unused powder is scraped off once printing is complete, and it may be collected to

be reused for future prints (L. Zhang et al., 2022). This technique does not require rheological

properties of materials supply like extrusion based printing because this technique uses

powdered material supply. Other material properties, such as particle size, flowability, bulk

density, and wettability of the powder, have a significant impact on the printing precision and

accuracy of objects produced through SLS (Godoi et al., 2016). Powder density and

compressibility play a significant role in this technique because they directly affect how

easily the powder flows within the vessel. This in turn affects the pattern formation when the

laser is applied to the powder bed and hence influences the overall quality and accuracy of

the printed structure (Godoi et al., 2016)(Kondor et al., 2013).This technique of laser

sintering is widely used in ceramic and metal industries. The material quality, which should

not decompose during the binding using laser, is considered here. The SLS technique is the

ability to create complicated and intricate 3D structures and can stand alone on themselves

without support. It allows for high resolution, and, therefore, objects printed using this

technique have very fine details. However, there is a limitation to this technique since it only

works with powdered materials. When it concerns edible food, material powders are usually

25
matters like sugar, fat, or starch granules are mostly uswed, thus limiting the possible

materials that are used in printing. The key processing factors consist of laser kinds, laser

diameter, laser energy, scanning rate, and printer should be tailored for desired performance.

2.2.3. Binder jetting based 3D food printing

Binder jetting was invented by Sachs, Haggerty, Cima, and Williams in 1994. It is the

process where a material is added as powder layers by layer while having a selective

application of binder in specific areas, depending on a digital design to fuse particles

together. Unfused powder provides support for the structure as it is created with high

precision to enable detailed designs, then can be taken off after its removal, allowing excess

powder to be recycled (Jee & Sachs, 2000). This technology makes it possible to create very

fine 3D structures and even colorful edible products by adjusting the composition of binders.

The technology is very limited in terms of its applicability in food industries because its

application requires an edible binder that is not applicable to traditional food products. Its

success depends upon the properties of both the powder material and the binder. The binder

should have appropriate viscosity, surface tension, ink density, and proper characteristics to

avoid uncontrolled spreading from the nozzle, and its concentration is a critical factor in

achieving dimensional accuracy (Melcher et al., 2006). The printed structures should have

adequate strength with minimal shrinkage, expansion, or binder bleeding (Vorndran et al.,

2015). Proper flowability of the powder was seen to be another very essential factor for

uniform layering, thereby achieving high precision and accuracy, while poor flowability was

used to induce defects (Lanzetta & Sachs, 2003). A good powder must have a free-flowing

nature along with non-sticky, anti-agglomeration property at an angle of repose below 30°

(Lee et al., 2015). Wettability is also crucial, as under-wetting may lead to rearrangement of

powder, which degrades the printing, and over-wetting results in a reduced resolution (Shirazi

et al., 2015). Edible powder, in this process, should have a moisture content less than 6%

26
(Vorndran et al., 2015), and wetting techniques can help control the migration of unbound

powder. Precision is dramatically affected by the particle size and distribution as variability

affects the size of the pore and binder, and therefore coarse and fine mixing is favorable,

according to (J. Zhang et al., 2021)(Vorndran et al., 2015). Further to this, a number of

printing parameters should also be optimized and these include head resonance frequency and

nozzle diameter (Shirazi et al., 2015), while for larger nozzles increase of speed with

compromised resolution, though. Some post-processing techniques like baking, heating, or

removing extra powder are essential for the mechanical strength and precision enhancement

(Vorndran et al., 2015). In addition to this, sprinkling of additives onto the printed food

structures helps in improving the flavor, color, and the overall outlook with the use of

adsorbability of the porous surface (Cheng et al., 2008).

2.2.4. Inkjet printing

Inkjet printing uses a thermal or piezoelectric printhead that releases droplets onto

targeted areas for surface filling or decorative imaging on food products such as cookies,

cakes, and pizzas (Rochus et al., 2007). There are two primary types of inkjet printing:

continuous jet printing and drop-on-demand printing. In continuous jet printing, ink is

constantly expelled through a piezoelectric crystal vibrating at a fixed frequency. To achieve

the desired flowability, conductive agents are added to the ink. In contrast, drop-on-demand

printing releases ink only when needed, using pressure applied by a valve. While drop-on-

demand systems generally operate at a slower printing speed compared to continuous jet

systems, they offer higher resolution and precision. Normally, a single print head continuous

jet printer can go as high as around 70–90 dots per square inch (dpi) (Pallottino et al., 2016).

Traditionally, inkjet printing is adopted for low-viscosity materials that have insufficient

mechanical strength to support a 3D structure. This makes it more useful in printing the

image only in two dimensions. In fact, for proper printing, parameters such as compatibility

27
between the ink and the surface of the substrate, viscosity, and rheological properties of ink,

temperature, and printing speed, are also critical to obtaining accuracy and precision in

printing (Z. Liu et al., 2017).

2.3. Applications of 3D food printing

2.3.1. Customization of Nutrition

The primary application of this 3D food printing is personalized nutrition, i.e.,

alteration or presetting of the nutritions based on the consumer requirements. The term is

applied for a "customized food formula" and entails the fabrication or formulation of foods

with the appropriate amount of nutrients and functional compounds needed for disease

prevention and protection against health (Severini & Derossi, 2016). As a layer-by-layer

building of 3D objects, there would be regular and equal distribution of nutrients. Not all the

food we eat in our daily life has all the required nutrients and some foods may be missing

some nutrients. This can put more emphasis on nutritional profiling by replacing some

ingredients with healthier options (J. Liu et al., 2019). Under the framework of the

"Performance" project, Biozoon Food Innovation produced cookies made of insect-based

flours to help individuals with chewing disorders (Additive Manufacturing Applications

within Food Industry: An Actual Overview and Future Opportunities, n.d.). Researchers have

also utilized 3D edible gel printers to make soft foods for elderly people to make swallowing

easier (Gong et al., 2014). For the purposes of swallowing disorders, TNO has developed

methods for printing pureed food, particularly for the benefit of older adults with chewing

and swallowing disorders. Besides that, personalized meals with optimized compositions of

nutrients for different age groups can also be prepared (Sun et al., 2024).In an interesting

research, scientists successfully 3D-printed cereal-based food structures embedded with

probiotics (L. Zhang et al., 2018). These innovations provide a new direction to research on

3D food printing, as probiotics have a significant role to play in the nutraceutical and

28
functional food sectors, which have a significant role to play in human health (Nachal et al.,

2019). The combination of 3D printing with nutrition also enables individuals to accurately

monitor and control their nutrient and calorie consumption.Food printing enables

personalized nutrient consumption through two principal means: (1) portion control and (2)

the modulation of natural or nutritional components in terms of concentration during

formulation (Sun et al., 2015). The technology enables the creation of functional foods

through the modification, replacement, supplementation, or elimination of certain ingredients

from raw materials (Severini & Derossi, 2016). New developments concentrate on nutrient

delivery by microencapsulation (Sun et al., 2015). Through one or more of these processes,

food printing provides an effective means of digitizing dietary and energy needs. It is

especially effective in developing food suitable for particular groups or professional groups.

For example, it can be used to provide soldiers with their own nutritional requirements and

enable on-demand food production on the battlefield. Shelf-life issues are also reduced since

most ingredients would be stored in their raw state (Sher & Tutó, 2015).

2.3.2. Culinary arts

3D food printing (3DFP) is a novel food technology that is creating new fronts of

food invention, personalization, and production. 3DFP is applied in industrial kitchens and

domestic kitchens, and it allows chefs to invent novel gastronomic ideas. The key benefit of

3DFP is the design of intricate and complex food forms, which cannot be achieved by

conventional cooking. As (Lipton & Lipson, 2016) note, 3D printing provides the benefit of

having maximum control over mixtures, texture, and shape, which is beneficial to the looks

of foods and functionality. This aspect is particularly crucial in haute cuisine where

appearance is as vital as taste. With 3DFP, cooks can utilize the capability to offer

personalized garnishes, ornaments, and organized layers with extremely high accuracy (M.

Wang et al., 2022). Moreover, 3DFP offers the possibility of preparing personalized meals in

29
line with special nutritional needs, e.g., gluten-free, low-calorie, or allergen-free meals.

(Côté-Allard et al., 2019) emphasize that the kind of personalization at these high levels

assures healthier consumption of food and potential control over nutrition, which is highly

relevant in medical and functional foods. There is prospective utilization of versatile

ingredients, like plant proteins. 3DFP has prospective application of varied materials, e.g.,

plant protein, as reported by (Piovesan et al., 2020). Future uses of environmentally

sustainable materials like seaweed or insect protein have been proposed through introduction

of novel gastronomy and green food manufacturing.

2.3.3. Globalization of Printed Foods

Developments in 3D food printing technology have enabled food designers to

exchange food designs, allowing them to download original data files and print foods when

necessary (Sun et al., 2024). It is possible with the technology to combine culinary skills and

artistic competencies into a printable file (Berman, 2012). With advancements in 3D food

printing, consumers may be enabled to create food items at home through the purchase or

download of designs from the internet. With the use of e-commerce sites and mobile apps,

consumers are able to personalize or buy designs, resulting in decreased distribution,

packaging, and storage costs, while streamlining the food service process. Each 3D food

printer may be designed to specific file/software specifications, with differences in print

quality between types of printers. As sharing of recipe files becomes more widespread, these

differences can potentially be resolved with the creation of standardized food printer setups.

The web-based marketplace for 3D food printing recipes will increase, fueling competition in

price, product adaptability, and beauty of printed food products. Moreover, tailored foods

manufactured by 3D food printing may be delivered to customers sooner than conventional

food processing (Sun et al., 2015). Shorter production times ensure higher food safety, in

theory preventing the use of chemical preservatives and polymeric packaging. Also, the

30
multi-step food production processes could be compressed into one step, making food supply

chains even less complicated and decreasing the number of processing steps.

2.3.4. Space foods

Space food is a crucial element of sustaining astronauts on long missions in that they

need to be healthy, lightweight, and storage-efficient. The present space food production

challenges are limited menu options, lower freshness, and more waste. 3D food printing may

address these challenges, and institutions like NASA are exploring whether this will improve

the nutritional value of space food. The technology provides the capability for printing

customized food in raw form that is accurately printed into complex geometries and shapes.

The 3D food printers possess the capability to print many meals from only a few mandatory

ingredients using squirting of the ingredients in layer form, thus saving on storage space

while providing fresh, varied, and healthy meals to the astronauts. This benefits them towards

happiness and health during long-duration missions. They are not only meant to be safe,

healthy, and delicious (Santhoshkumar, Negi, et al., 2024), but also light and easy to

maneuver, given the special space environment of microgravity that affects eating and food

preparation (Macdonald et al., 2016).

2.3.5. Health and medical applications

Growing interest in 3D food printing for medical and health applications has been

stimulated by its potential to deliver personalized nutrition and therapeutic diets. Studies have

shown that 3D food printing can print meals according to an individual's dietary needs, such

as patients suffering from diabetes, heart disease, and metabolic disorders (Y. Liu et al.,

2020). Through precise control of ingredients and their nutrient content, 3DFP delivers

patients precisely prepared meals in accordance with each patient's own nutritional

requirements. 3DFP can also be used to create foods varying in texture, such as more easily

31
consumed food for dysphagia or other swallowing disorders (Sager et al., 2020). This is much

better than traditional food preparation in both comfort and safety of the patient. Furthermore,

3D printing can also be applied to the development of functional foods supplemented with

some nutrients like vitamins, minerals, or proteins for the use of medical therapy or post-

operative or disease recovery (Shafiee et al., 2021). Another advantage is the capability of

3DFP to produce more esthetically attractive and acceptable-looking meals, which are very

important in ensuring patients on restricted or therapeutic diets have an improved quality of

life. In general, application of 3D food printing in healthcare has the promising potential for

more effective, individualized, and patient-centered nutritional therapy.

2.3.6. sustainability and resource efficiency

Three-dimensional printing (3D printing, 3DFP) has been a technology of the future

to realize the highest level of sustainability and efficiency of use in most industries. The

research had established that 3DFP would be able to prevent material wastage by additive

manufacturing, where materials are added layer upon layer only where required, compared to

traditional subtractive methods. The technique reduces wastage and improves the utilization

of raw material efficiently (Huang et al., 2013). Secondly, 3D printing helps in recycling

recyclable products like plastics and metals towards circular economy (Gao et al., 2015). 3D

printing has also been applied in construction for the construction of low-energy, affordable

homes with locally sourced materials, saving transportation cost and energy usage (Van

Renterghem et al., 2020). Secondly, it is highly probable to construct complicated patterns

maximally energy-efficient using energy such as light construction or heat transfer

streamlined in the automotive and aviation industries (Bogue, 2013). Besides such

advantages, applications have difficulties replicating at mass industrial scales. The power the

3D printers consume and material eco-costs such as non-biodegradable plastics are some of

the factors that must be weighed to quantify the technology's sustainability. In general, 3D

32
printing has great potential for sustainable production and energy conservation, but additional

innovation in material and energy efficiency is needed before it can achieve its full capability.

2.4. Circular economy

Implementation of circular economy principles to three-dimensional printing (3DFP)

has been of utmost importance with promising potential for increasing sustainability and

efficiency in the utilization of resources. A circular 3DFP economy seeks to recycle parts,

prevent wastes, and recycle materials again to minimize harmful environmental effects of

manufacturing activities. There is evidence that 3DFP can support a circular economy since it

can use recycled materials such as metal powder or thermoplastics and reduce virgin material

consumption (Gao et al., 2015). The method not only conserves resources but also supports a

closed-loop process where products can be broken down and reprinting into new products at

product lifecycle termination (Jovanović et al., 2021). Literature reveals some parameter of

on-demand printing of components and spares without bulk production and shipment and

thereby avoiding wastage and greenhouse gas emission (Gibson et al., 2015). Aside from

that, material science technology developments are also facilitating the creation of

biodegradable and bio-derived filaments which also make 3DFP nearly a circular economy

(Vaezi et al., 2013). But still, such problems as materials that are non-recyclable, energy-

guzzling print processes, and optimizing waste processing operations still need to be solved.

But through ongoing evolution in 3DFP technology coupled with increasing priority to the

circular economy, enormous potential exists in the transition toward cleaner production

modes

.2.6. Functional food development from waste

Functional food production from waste by three-dimensional printing (3DFP) has

been one of the latest methods for curbing food wastage as well as meeting the growing

demand for health foods. Evidence in this context suggests the potential of 3DFP to produce

33
functional foods from food waste and by-products, i.e., fruit peels, seeds, and spent grains,

that are packed with nutrients like fiber, antioxidants, and proteins (Escobedo et al., 2020).

By incorporating such waste products in 3D-printed food materials, researchers have been

able to create food items with augmented nutritional contents, like energy bars, snacks, and

personalized meal options (Xie et al., 2020). Additionally, 3DFP permits regulation of

texture, shape, and composition of nutrients in the final food and consequently food

manufacturing with beneficial functional attributes, like better gut health or antioxidant

defense (Escobedo et al., 2020). 3DFP is also a promoter of sustainability as it decreases

wastage of food and least use of added raw materials, thus enhancing the circular economy

(Guojun et al., 2018). In spite of all these benefits, there are setbacks like tuning printing

conditions, sensory attributes, and consumer acceptability of 3D-printed foods from food

wastage. In spite of all this, innovation in 3D printing technologies and food technology is

bringing about new possibilities of creating sustainable, food-grade functional foodstuffs

from wasted food, which could become an alternative for the food industry as well as for

sustainability.

2.7. Watermelon

Originated from the tropical regions of Africa, particularly in the vicinity of the

Kalahari Desert (Romdhane et al., 2017; Naz et al., 2014), watermelon belongs to the

Cucurbitaceae family. It is mainly eaten in summers as it is a sweet refreshing fruit because

consumers want to have this fruit for quenching their thirst in a hot climate when its

hydrating property, vibrancy in colour, mildness in taste, and high water content are worthy

for them. The watermelon fruit has a thick rind (exocarp) with variable pigmentation; it may

range from solid to striped patterns. It also includes a fleshy mesocarp and an endocarp,

which has a white to yellow or even red color (Bahari et al., 2012; Munisse et al., 2013). The

34
flesh of watermelon is replete with carotenoids, vitamins A, B6, and C, lycopene and

antioxidants. More importantly, watermelon peels are edible and full of various nutrients

(Jensen et al., 2011). Watermelon also contains citrulline, a non-essential amino acid, which

it is a good source of (Soteriou et al., 2014). The watermelon is sweet because it has a

mixture of sucrose, glucose, and fructose. Sucrose and glucose account for 20–40% sugars,

whereas fructose accounts for 30–50% sugars in a fully matured fruit of watermelon (Bianchi

et al., 2018). The consumption of watermelon has therefore been linked to various health

advantages including reduced cardiovascular diseases, age-related degenerative disorders,

and certain cancers (Choudhary et al., 2015; Romdhane et al., 2017). A U.S. Department of

Agriculture, Agricultural Research Service reports that only half of a watermelon is

consumable, while the rest is waste, composed of about 35% rind and 15% peel. In addition,

the watermelon rind, with carboxyl and amino groups, has a high capacity to chelate heavy

metals from aqueous solutions (Rimando et al., 2005). Hence, research into the use of

watermelon rind as a novel biosorbent for the removal of heavy metals can help reduce agro-

waste from watermelon.(Nachal et al., 2019)

2.8. Food waste valorisation

The total amount of food produced around the world to be consumed by humans is

about one-third annually. It goes approximately 1.3 billion tonnes, consisting of various kinds

of food types: cereals, roots, tubers, oilseeds, pulses, fruits, vegetables, meat, seafood, milk,

and eggs. A report by the Food and Agriculture Organization (FAO) of the United Nations

indicates that food loss and waste occur at every stage in the food supply chain, from

production to disposal by consumers (Gustavsson et al., 2011; Gustavsson et al., 2013).

Whether it occurs early or late in the supply chain, the discarded food usually ends up in a

landfill or treated to eliminate environmental risks. This requires appropriate management

mechanisms, especially when dealing with regions with high populations because food

35
wastes are a probable cause of considerable public health risk. Food wastes cannot be

appropriately disposed of in landfills, since the entire food production system involves high

levels of energy and resources (Cuéllar et al., 2010; Zilbermann et al., 2013).

A further alternative to tackling food waste would be valorization, a method of converting

waste materials into higher-value and useful products (Arancon et al., 2013). Valorizing food

waste does not only bring monetary benefits to the food manufacturing industries by adding

value to by-products but also answers the significant quantity of waste that is produced. For

instance, most fruits, including watermelon, have only half of them utilized, where the flesh

is consumed and the rind and peel are peeled off as waste. However, these wastes contain the

majority of the nutrients and bioactive compounds. The watermelon rind has been identified

as a potential candidate for valorization, either by recycling it as animal feed or by processing

it for human consumption due to its acceptable taste and flavor profile. Thus, food waste

valorization presents an opportunity to reduce environmental impact while simultaneously

enhancing the economic value of previously discarded materials.

United Nations (UN) Sustainable Development Goals (SDGs) focus attention on the

significance of food waste management in order to achieve specific global targets. In

particular, it supports the attainment of SDG 2 (Zero Hunger) by cutting down on wastes and

channeling the resources for feeding vulnerable groups. Food waste management also enables

the production of renewable energy to help attain SDG 7 (Affordable and Clean Energy).

Finally, it plays an important role in SDG 12 (Responsible Consumption and Production),

focusing on resource-efficient use, lowering environmental impact, and promoting

consumption practices around the world. Aniruddha Sarker et al., 2024.

2.9. Gummies

In recent times, demand for alternatives to supplement intake has been on the rise.

Gummies, in particular vitamin gummies in the form of chewable gel, have gained popularity

36
because they are easy to consume, visually appealing, and flavorsome, hence highly attractive

to children and older adults (Byan et al., 2021). The production of gummies includes high-

temperature boiling of sugars and gelling agents (>110°C) and adding flavors, colorants, and

active ingredients like vitamins at 80-90°C. It is then molded and dried (Mutlu et al., 2018).

The shelf life for gummy supplements is generally within 1-2 years in standard conditions,

that is, 20-25°C, 50-60% relative humidity (Appleton et al., 2018). Gummies are sugar-based

confectionery that enable people to take their supplements in an easy and light-hearted way.

Gelatin is commonly used as a gelling agent to provide firmness; it is sourced from animal

collagen and, thus, cannot be used by a vegan. Consequently, vegan gummies use plant-based

gelling agents: pectin, agar-agar, xanthan gum, gellan gum, and carrageenan, to achieve the

desired gelling characteristics.

Fruit by-products and waste streams are significant reservoirs of nutritional value, bioactive

compounds, and dietary fiber contributing to human nutrition (Sagar et al., 2018). Because of

their composition, these by-products and industrial by-products can be considered low-cost

raw materials for improving food formulations. Most of these materials require only limited

processing: particle size reduction and drying-in order to be effectively used. There has been

increasing interest in incorporating fruit wastes into the confectionery industry lately (Cappa

et al., 2015; Da Silva et al., 2016). Gummies, which typically use fruit pulp or concentrate as

a flavoring and base, would greatly benefit from using fruit by-products as a more cost-

effective alternative.

37
38
 Materials and methods

CHAPTER III

3. MATERIALS AND METHODS

There is no much ingredients required but few which have impacted in different aspects when

a slight changes made in the composition.The supporting materials like sugar and watermelon

39
were purchased from local markets of Thanjavur, Tamilnadu, India. High methoxyl (HM)

pectin (slow-set) was purchased from Marine Hydrocolloids™, Kochi, Kerala, India, and

citric acid was purchased from Himedia Laboratory, Mumbai, India.

The watermelon rind is scrapped out from the fruit and processed in two ways to add as an

ingredient. The rind was sliced into pieces and dried in hot air oven at 60 ℃ for 24 hours in

hot air oven. Dried pieces were pulverized into powder using (Vidiem Mixer Grinder 518A

VSTAR) and collected. Since it is hydrophobic in nature it tends to absorb more moisture and

makes it difficult to printing so called non-natively printable ingredients.

Alternatively the rind slices were blanched in heating water (~70 ℃) for 5 minutes and let it

cool to room temperature (25 ± 3 °C), then ground into a paste using a mixer grinder (Vidiem

Mixer Grinder 518A VSTAR) for 60 seconds, and the total soluble solid of this paste is ~5

°Brix (measured using a digital refractometer, ATAGO Co. Ltd, Japan; accuracy: ± 0.1%).

This form of rind performs as better ingredient and ease printability of the overall material

supply.

Fig 3.Watermelon rind slices Fig 4. Blanched watermelon rind Fig 5. Ground rind puree

According to the earlier trials, determined the formulations watermelon rind puree, sugar and

citric acid composition were 25, 50, and 0.5% (w/w). HM-pectin was added in different

amounts on a w/w basis, such as 0% (PEC 0), 5% (PEC 5), 10% (PEC 10), 15% (PEC 15),

and 20%% (PEC 20) by varying water content. Gummies were formulated mainly with

gelatin as thickening agent, since it is an animal source vegans would not prefer it. So, pectin

40
is used as thickening agent, pectin is considered as a Generally Recognized As Safe (GRAS)

additive. A homogenizer was used to mix the material supplies after adding the necessary

quantity of each ingredient, resulting in a semi-solid consistency.

3.1. Preparation of material supply

Mixing pectin with some part

of sugar.

Heat the water at a

temperature of 75°C

Blend the pectin sugar

mixture in hot water with the
homogenizer.

Dissolve the remaining sugar

in puree.

Mix all the ingredients puree

mixture, dissolved pectin and
citric acid together in a mixer.

Pour it into the feed tank.

The mixing of pectin was one of the most difficult parts in the preparation of material

supply. Since, the percentages of pectin and water doesn't meet the requirement for the

dissolution, the pectin was compulsively dissolved in the minimal amount of water with the

help of homogenizer and powdered sugar. The premixing of powdered sugar prevents the

clump formation while mixing. This would also mean that sugar helps evenly hydrate while

dispersing HM pectin without clumping. When HM pectin is added to water, there is a

41
significant absorption of water due to its hydrophilic natures, which can lead easily to

clumping, interfering with proper dissolution. Initially, the sugar particles act as a dispersing

agent that coats the pectin granules and separates them. When introduced into water, these

will gradually and evenly hydrate. The dispersion mechanism increases solubility and allows

for a smooth, lump-free solution. In addition, sugar competes with pectin for water

molecules, reducing water availability and encouraging pectin-pectin interactions that are

essential for gel formation. This controlled hydration process is important in food

applications ensuring proper functionality of HM pectin for gelation and texture formation.

3.2. Assessment of Quality

3.2.1. Water activity and color

Water activity (aw) was determined using an Aqua Lab 4 TE (Decagon Devices, Inc.

Pullman, WA, USA) dew point water activity meter (± 0.001 sensitivity). Hunter lab

colorimeter (ColorFlex EZ 45/0-LAV, Hunter Associates Laboratory Inc., VA, USA) was

used to quantify the color values L* (lightness), a* (redness) and b* (yellowness). The total

color difference (ΔE) of samples was calculated using the formula below,

∆ E=√ ∆ L¿2 + ∆ a¿2 + ∆ b¿2

2

3.2.2. Texture

A texture profile analysis of the material supply formulations and the printed

gummies was conducted using a texture analyzer (TA-HD plus, Stable Micro Systems Ltd.,

UK). A cylinder measuring probe (P/5) was used for pre-test 1 mm/s, test 1 mm/s and post-

test 10 mm/s conditions to determine the hardness, adhesiveness, springiness, cohesiveness,

gumminess, chewiness and resilience of samples.

3.2.3. Rheology

A parallel plate rheometer (MCR 52 series, Anton Paar Co. Ltd., Austria) was used to

analyze the rheological behavior of the printing material supplies. This study was carried out

42
by pre-establishing a 2000 μm gap between parallel plates with of 25 mm diameter and

ramping the shear rate from 0.1 to 100 s. The obtained values were fitted into the power law

model (Eq. 1) to establish an apparent viscosity curve.

(n−1)
η=Κ γ ……………………………… Eq. (1)

Where,

η - Apparent viscosity (mPa.s)

K - Consistency index (Pa.sn)

γ - Shear rate (s-1), and

n - Flow behavior index

3.2.4. Thermal behavior

A differential scanning calorimeter (DSC3, Mettler Toledo, Switzerland) was used to

study the melting behavior of material supplies following the methodology described by

Kavimughil et al. [18] with slight modifications. In brief, 3 mg of the sample was weighed

into a sealed aluminum pan and heated at a rate of 5 °C per minute while nitrogen flowed at a

rate of 30 mL per minute, and spectra were observed from the temperature of 25 °C to 120

°C.

3.3. 3D printing and optimization

The printing optimization study used an in-house fabricated Multi-CARK-Controlled

Additive Manufacturing Robotic Kit (CARK) extrusion-based 3D food printer (Fig. 1a) and a

"twisted hexagon" model: diameter 30 mm and height 30 mm (Fig. 1b) was selected. The

material was manually filled into the syringe of the barrel assembly. The slicing software

Simplify 3D (Ver. 4.1.0) was used to communicate with the printer. Based on preliminary

analysis, material supplies with five different concentrations of pectin were analyzed with

three different nozzle sizes: 0.6, 0.84, and 1.22 mm nozzle diameters with three different

printing speeds: 600, 800 and 1000 mm/min with the printing temperatures of 60-100 °C,

43
infill: 75%, motor speed 60 rpm and the pressure ⁓1.5 bar, was considered for optimization

parameters. The extrusion rate was determined by adapting the methodology followed by

(Anukiruthika et al., 2020).

Fig. 6. a) Multi-CARK 3D food printer b) Selected 3D geometry for this study (Twisted hexagon)

3.4. Sensory evaluation

A sensory evaluation was carried out considering two aspects of the printed gummies:

visual sensory and product sensory acceptance. Both studies were carried out with 25 semi-

trained panelists between the ages 18-36 years who rated the products using a hedonic scale

(1: dislike extremely; 2: dislike very much; 3: dislike moderately; 4: dislike slightly; 5:

neither like nor dislike; 6: like slightly; 7: like moderately; 8: like very much; 9:like

extremely). The visual sensory study considered properties such as texture, thread quality,

shape, finishing, appearance, binding property and dimensional stability (Santhoshkumar et

44
al., 2024a). The product sensory study focused on evaluating the product's appearance, color,

aroma, flavor, texture, taste, aftertaste, and overall acceptance (Santhoshkumar et al., 2024b)

3.5. Statistical analysis

The experiments were performed in triplicates, and the results were analyzed using

one-way analysis of variance (ANOVA). Significant differences were calculated by Duncan's

multiple range test (DMRT) using OriginPro software 2023b ® SR1 (10.0.5.157 edition), and

p < 0.05 was considered to be statistically significant.

3.6. Proximate analysis

3.6.1. Moisture content

The moisture content of the watermelon rind, material supply, and printed gummies

were measured and carried out in triplicate as loss in the sample's weight on heating at 105°C

for 3 hrs. 2 g of the sample was taken in weighed stainless-steel dish having lids. A hot air

oven was used to heat the samples in the dishes. The dishes were then placed in a desiccator

after drying. The intial and final weight of dish were noted (AOAC, 2000) the moisture

content was calculated (Tobaruela et al., 2018), (AOAC, Moisture, 1999)

Initial weight of dish with sample ( g ) −Final weight of dish with sample (g)
MC= ×100
weight of sample taken(g)

3.6.2 Protein content

Protein is an essential macronutrient important for muscle growth, tissue repair, and

overall health, so knowing the protein content helps individuals meet their daily nutritional

requirements. Protein estimation for all three samples(watermelon rind, material supply, and

printed gummies) was determined by the AOAC (2000) method. 1 g of the sample was

hydrolysed with 10 mL of concentrated H 2SO4, 5 g Na2SO4, and 1 g CuSO4 were added and

45
the contents were mixed in a digestion flask at 420℃ for 2 hrs. Boric acid of 4 % was added

to the acid tank and the alkali tank was filled with 40 % NaOH solution. The digested sample

in the Kjeldahl tubes was distilled in the presence of acid and base and the distillate was

collected in a 250 mL conical flask. Two drops of mixed indicator solution were added into a

conical flask containing the distilled sample. The distillate was then titrated with 0.1 N HCl,

solution until it became pale pink colour. The percent total nitrogen and crude protein were

calculated using. and total nitrogen was calculated by multiplying with a conversion factor of

6.25. Each measurement was carried out in triplicates to ensure the value of concordant.

TV −BV × Normality of acid ×14.01 ×100

N %=
w × 1000
Where, TV= Titre value, ml BV= Blank value W = Weight of the sample, g N = Nitrogen

%Protein = %Nitrogen ×6.25

3.6.3. Fat content

Determining fat content in the sample is crucial for assessing nutritional value and

caloric density, aiding in dietary planning and maintaining healthy lipid intake levels, thereby

contributing to overall health and well-being. The fat content in all three samples

(watermelon rind, material supply, and printed gummies) was measured using Soxhlet

extraction, a modified AOAC method (1995). The sample (5g) was placed in a pre-weighted

filter paper and suspended above a pre-weighed receiving flask holding 90 mL of hexane

(boiling point 40-190°C) coupled to a Soxhlet extraction assembly. The flask was heated on a

heating mantle at low temperatures (40-60°C) for 2 hours. The thimble containing the filter

paper was removed, and the spirit evaporated and collected, leaving the extracted fat in the

flask. The flask was moved to a desiccator and weighed. The percentage of fat was calculated

as,

Weight of fat ( g )
Fat content %= ×100
Weight of sample ( g )

46
3.6.4. Total ash

Determining ash content in the sample is crucial for assessing their purity and quality.

Ash content indicates the amount of inorganic mineral matter present, aiding in nutritional

analysis and ensuring adherence to regulatory standards for food safety and authenticity. Ash

was determined for all three samples (watermelon rind, material supply, and printed

gummies) in triplicates (AOAC, 1990). 2 g of sample was weighed into a previously dried

and weighed porcelain crucible. The crucible with the sample was placed in a furnace and

heated to 550°C for 6 hrs. Then, the crucible was cooled in a desiccator till it reached room

temperature and reweighed. The weight of the ash was calculated.

(Weight of Crucible after ashing−Weight of empty crucible)

Ash= × 100
Weight of sample (g)
3.6.5. Crude fiber

Determining crude fiber content in the sample provides insights into their dietary fiber

composition, aiding in nutritional labeling and assessing their potential health benefits related

to digestion and metabolism. Crude Fiber for all three samples (watermelon rind, material

supply, and printed gummies) was measured by Wende’s method (AOAC, 1995). 1 g of

sample was treated with 100 mL of 1.25 % of H2SO4 and the mixture was heated till the

sample was reduced to half of its original volume. This was filtered using a muslin cloth and

digested with 100 mL of 1.25 % NaOH solution. Heating and filtration were repeated.

Finally, the mixture was filtered by using Whatman filter paper and dried in a hot air oven at

130°C for 2 hours, and then ignited for 30 minutes at 600°C. Crude fibre was calculated

using the formula below,

Weight of residue
% Crude Fibre= ×100
Weight of sample

3.6.6. Determination of Carbohydrate:

47
 Carbohydrate content of the sample was calculated using the difference method. It is

computed by removing the sum of moisture, protein, fat, and ash content from 100 as shown

in the formula below.

Carbohydrate = 100 - (Moisture + Ash + Protein + Fat + Crude Fiber)

3.6.7. Determination of Energy Value:

Energy value of the sample was determined by Theoretical method using the formula

given below. It is expressed in Kcal/g.

Energy Value (Kcal/g) = (9×fat) + (4×carbohydrate value) + (4×protein value)

48
Result and discussion

49
 CHAPTER IV

4.0.RESULTS AND DISCUSSION:

4.1.Material supply characterization

4.1.1. Water activity

Maintaining appropriate moisture in the material supply is crucial for obtaining proper flow

and shape precision during the printing process. Table 1 presents the aw values of the

material supplies. All material supplies belong to the category of 'high moisture'. Notably, aw

values significantly decreased with an increase in pectin concentration from 0 to 20%. This

can be attributed to the impact of higher soluble solids on forming looser gel networks and

the resulting hydrophobic interactions that stabilize junction zones [22]. The obtained results

were comparable to the results reported in a 3D printing study on fortified products from

millet reported by Raja. et al. [23].

Sample Water activity

PEC 0 0.92 ± 0.01d

PEC 5 0.90 ± 0.01c
PEC 10 0.88 ±0.00b
PEC 15 0.87 ± 0.01b
PEC 20 0.85 ±0.01a
Table 4.1.1. Water activity of material supplies
4.1.2. Color

The different concentrations of pectin impact the material supplies' color values (Table 1). A

higher pectin concentration (PEC 20) led to increased lightness (55.38 ± 3.45), redness (2.02

± 0.02), and yellowness (19.81 ± 0.02). The rise in solid content significantly influenced

these color values. Additionally, watermelon rind contributed more to the yellowness index

50
of the material compared to redness. The increase in yellowness of the rind can be attributed

to the heat treatment during blanching, which destabilizes chlorophyll, leading to its

conversion into pheophytin, an olive-green or yellowish pigment [24]. The total color

difference (ΔE) values were calculated using PEC 0 as the reference. As the pectin

concentration increased, the ΔE values rose significantly, with the PEC 20 sample exhibiting

the highest total color difference of 36.74.

Color
Sample
L* a* b* ΔE
PEC 0 23.56 ± 0.02a -1.34 ± 0.00a 1.77 ± 0.03a -
PEC 5 45.51 ± 0.02b -0.80 ± 0.01b 10.74 ± 0.03b 23.72
PEC 10 51.09 ± 0.12c 0.20 ± 0.01c 16.39 ± 0.02c 31.22
PEC 15 51.27 ± 0.06c 1.25 ± 0.01d 19.60 ± 0.01d 33.05
PEC 20 55.38 ± 3.45d 2.02 ± 0.02e 19.81 ± 0.02e 36.74
Table 4.1.2. Color of material supplies

4.1.3. Texture

The mechanical strength of the material supplies influences printability and post-printing

behavior. That is, the hardness of the material supply determines the amount of extrusion

force required by the 3D printer to push the material supply out through the nozzle; it was

observed that higher forces are required for PEC 15 and PEC 20 than the other material

supplies .A higher pectin concentration leads to a denser network of pectin molecules,

increasing the material's resistance to deformation. In addition, the higher hardness represents

the material supply strength, thus exhibiting a stronger structure network after depositing on

the printing platform. The higher adhesiveness improves layer bonding and overall structural

integrity. Likewise, the lower adhesiveness leads to easier detachment from the printing

nozzle and printing platform. The adhesiveness decreased as the pectin concentration was

increased. This may be due to the higher concentration of pectin forming a stronger network

51
structure, increasing the viscosity, thereby improving intermolecular bonding and surface

contact. The higher value for springiness indicates a material with greater elastic recovery,

implying that it can return to its original shape more effectively after deformation. This also

helps in improving the adhesion between layers, resulting in a stronger and more stable print.

However, springiness remains relatively consistent (~0.9) with increasing pectin

concentration (PEC 5 – PEC 20) than PEC 0.

Sample Hardness (g) Adhesiveness (g.s) Springiness

PEC 0 2.28 ± 0.21a - 0.33 ± 0.58a

PEC 5 6.51 ± 0.53a -4.98 ± 0.40d 0.98 ± 0.01b

PEC 10 32.94 ± 1.89b -19.57 ± 0.44c 0.96 ± 0.02b

PEC 15 100.18 ± 16.76d -35.22 ± 3.41b 0.86 ± 0.11b

PEC 20 234.81 ± 18.62e -73.51 ± 1.37a 0.94 ± 0.05b

Cohesiveness is the degree to which a material resists breakage and decreases with increasing

pectin concentration (PEC 0 – PEC 20). Increased pectin concentration can form a rigid

network, reducing plasticity, increasing brittleness and decreasing cohesiveness. Chewiness

and gumminess are related to the energy required to masticate and break up food. Higher

gumminess and chewiness can lead to nozzle clogging and difficulty in extrusion but also

improve the final product's texture and structural integrity. Gumminess and chewiness

increase with increasing pectin concentration (PEC 0 – PEC 20). Higher resilience improves

shape retention and layer adhesion and enhances the overall durability of the 3D-printed

gummies. These findings are comparable to the previously reported starch gummies-based

3D printing study by Niu. et al.

Table 4.1.3.(a) Textural attributes of the material supplies

52
 Sample Cohesiveness Gumminess Chewiness Resilience

PEC 0 0.94 ± 0.54a 2.37 ± 4.11a 2.39 ± 4.14a 1.44 ± 1.37a

PEC 5 0.83 ± 0.01b 5.46 ± 0.38a 5.36 ± 0.44ab 0.01 ± 0.00a

PEC 10 0.77 ± 0.02ab 25.38 ± 0.65b 24.55 ± 0.68b 0.051 ± 0.00a

PEC 15 0.58 ± 0.17ab 57.84 ± 16.56c 51.45 ± 21.41c 0.04 ± 0.01a

PEC 20 0.61 ± 0.08ab 143.4 ± 14.41d 135.62 ± 13.77d 0.04 ± 0.00a

Table 4.1.3.(b) Textural attributes of the material supplies

4.1.4. Rheological behavior

The effect of varying material supply compositions on the rheological behavior was analyzed

by measuring the apparent viscosity of the material supplies. Fig. 2 elucidates that all material

supplies exhibited shear-thinning behavior, indicating a decrease in the apparent viscosity of

the material with an increase in shear rate. This result was supported by the flow behavior

index (n) values being less than 1 (Table 3). Materials with shear-thinning characteristics are

widely suitable for 3D extrusion-based food printing applications [26]. All material supplies

exhibited shear-thinning characteristics; however, the initial viscosity profile was changed

while increasing the pectin concentration, which relates to the hardness of the material

supplies. Nevertheless, the higher strength of the gel network gives more support to the

upcoming layers while printing. Although all formulations showed shear-thinning effects, the

amount of extrusion force required to push the material out of the nozzle would vary and

have a significant effect in determining the final printability of the material supply. It was

observed that the pectin concentration significantly influenced the consistency coefficient (k).

53
Among the different formulations, PEC 0 had a more liquid-like consistency; following that,

PEC 5 and PEC 10 showed such effects. A higher percentage of PEC 15 and PEC 20 holds

sufficient consistency coefficient values [19]. Specifically, in a pectin-based study on drug-

loaded gummies, a reduction in viscosity was reported while increasing the shear rate and

was explained to be caused by the alignment of transiently elongated coils in the flow

direction by the polymer chains [27].

Sample k n R2

PEC 0 340 ± 0.00a 0.26 ± 0.22a 0.99

PEC 5 340 ± 0.00a 0.31 ± 0.14a 0.99

PEC 10 339.99 ± 0.00a 0.27 ± 0.22a 0.99

PEC 15 340 ± 0.00a 0.40 ± 0.00a 0.99

PEC 20 368.38 ± 49.16a 0.32 ± 0.13a 0.99

Table 4.1.4. Rheological behavior of the material supplies

54
 Fig. 7. Shear ramp curve for the material supplies

4.1.5. Thermal behavior

The different concentrations of the pectin change the melting behavior of the material

supplies (Fig. 3). Samples PEC 5, PEC 10, PEC 15 and PEC 20 exhibited peak melting

temperatures of 110 °C, 114 °C, 116 °C, and 120 °C, respectively. The elevated melting

temperatures are essential for hot extrusion 3D printing applications, as they guarantee the

thermal behavior of the materials during the printing process [28]. Maintaining the pectin's

structural integrity, these high melting temperatures contribute to the overall mechanical

properties and desired characteristics of the final 3D-printed gummies. Further, it indicates

that pectin within the formulation remains stable and does not undergo denaturation if the

printing temperatures are less than this melting temperature (<110 °C).

55
 Sample Temperature(⁰C)

PEC 5 110 ⁰C

PEC 10 114 ⁰C

PEC 15 116 ⁰C
PEC 20 120 ⁰C

Table 4.1.5. Thermal behavior of material supplies

4.2. Optimization of hot extrusion 3D printing conditions

Material properties and process parameters should be closely investigated to obtain precise

printed constructs. Based on the material characteristics, a pectin concentration of more than

5% was found to provide sufficient mechanical and textural properties. Nozzle diameter,

nozzle height, extrusion rate, and nozzle speed are very crucial processing parameters for

obtaining good printed constructs. The observation of varying these printing conditions for

the different pectin concentrations is presented in Table 4. In this table, 'desired extrusion'

represents the stable printed structure with high precision. The material deposition was

expressed as the extrusion rate, which remained constant across different printing speeds due

to the consistent pressure and motor speed. The desired extrusion was obtained with PEC 10.

'Over extrusion', implying that the excessive deposition of material on the printing platform

or layers was observed in the PEC 5 samples. This caused the layers to lose their defined

positions and merge with adjacent layers, leading to shape collapse and 'under extrusion',

implying that less material deposition or not able to form a desired shape, was noted in PEC

15 and PEC 20, possibly due to the lack of extrusion caused by less pressure and motor

speed.

Temperature is a crucial factor in preparing the gummies as well as in achieving the desired

printed constructs. With the sufficient viscosity of the material supply, PEC 10, with

56
temperatures of 60 and 80 °C, could be printed with high precision at printing speeds of 600

and 800 mm/min, while at 100 °C, over extrusion was observed. Without pectin, PEC 0 was

not printable; similarly, at higher concentrations, PEC 20 was found to become rigid, and the

printing operation requires more force and extrusion pressure to flow the material from the

feeder to the nozzle.

The desired 3D geometry can be obtained if a proper nozzle height is maintained throughout

the printing process. The critical height of the nozzle was calculated by the methodology

adapted from Anukiruthika et al. [19]. The critical height of the nozzle was maintained at

>0.05 mm to obtain the desired extrusion of the sample. Choosing the smallest nozzle tip that

facilitates simple material extrusion is a safe practice because it helps to create the product

with the best resolution and smoothest surface during printing. Among all, the 0.84 mm

nozzle diameter was better than others when considering the product's quality and the

effectiveness of 3D printing. In the context of printing speed, 800 mm/min could achieve

better results than 600 mm/min because of faster printing, and this printing speed is directly

proportional to the fixed motor speed, 1.5 bar pressure and temperature.

The volumetric flow of the material deposited in a specific amount of time is known as the

extrusion rate, and it significantly affects the quality of the final product and printing

accuracy. It has been reported that the extrusion rate and printing speed have a linear

correlation [29]. However, the extrusion rate remained constant at 60 and 80 °C in a nozzle

with 1.22 mm. Due to their simultaneous effects on the amount of extrusion per unit length

per unit time, extrusion rate and nozzle movement speed have an impact on 3D printing. The

ideal temperature was 80 °C because it produces high-quality and precise gummies.

Sample Nozzle Temperature Printing speed (mm/min)

diameter (℃)

57
 600 800 1000

PEC 0 Not printable

60

Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
2.83 ± 0.25a
(g/min)

80

0.6 mm Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
2.70 ± 0.43a
(g/min)

100

PEC 5
Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
2.60 ± 0.34a
(g/min)

60

Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
2.96 ± 0.20a
(g/min)
0.84 mm

80

Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
2.13 ± 0.30a
(g/min)

58
 100

Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
3.10 ± 0.1b
(g/min)

60

Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
2.63 ± 0.28a
(g/min)

80

Observation Over extrusion Over extrusion Over extrusion

1.22 Extrusion rate

2.83 ± 0.30a
(g/min)

100

Observation Over extrusion Over extrusion Over extrusion

Extrusion rate
3.06 ± 0.15b
(g/min)

PEC 10 0.6 mm

60

Observation Over extrusion Over extrusion Over extrusion

Extrusion
0.83 ± 0.15a
rate (g/min)

80

Observation Desired Desired extrusion Under extrusion

extrusion

59
 Extrusion
1.46 ± 0.15a
rate (g/min)

100

Observation Over extrusion Over extrusion Under extrusion

Extrusion
1.83 ± 0.05a
rate (g/min)

60

Observation Over extrusion Over extrusion Under extrusion

Extrusion
1.56 ± 0.15b
rate (g/min)

80

0.84 mm Desired
Observation Desired extrusion Under extrusion
extrusion

Extrusion
2.00 ± 0.10b
rate (g/min)

100

Observation Under extrusion Under extrusion Under extrusion

Extrusion
2.40 ± 0.10b
rate (g/min)

60
1.22 mm

Observation Over extrusion Over extrusion Under extrusion

Extrusion 1.90 ± 0.10c

rate (g/min)

60
 80

Observation Under extrusion Under extrusion Under extrusion

Extrusion
2.33 ± 0.15c
rate (g/min)

100

Observation Under extrusion Under extrusion Under extrusion

Extrusion
2.66 ± 0.25b
rate (g/min)

PEC 15 60

Observation Under extrusion Under extrusion Under extrusion

Extrusion
0.86 ± 0.20a
rate (g/min)

80

Observation Under extrusion Under extrusion Under extrusion

0.6 mm

Extrusion
0.73 ± 0.15a
rate (g/min)

100

Observation Under extrusion Under extrusion Under extrusion

Extrusion
0.70 ± 0.10a
rate (g/min)

60

61
 Observation Under extrusion Under extrusion Under extrusion

Extrusion
1.13 ± 0.11ab
rate (g/min)

80

Observation Under extrusion Under extrusion Under extrusion

Extrusion
0.84 mm 1.33 ± 0.15b
rate (g/min)

100

Observation Under extrusion Under extrusion Under extrusion

Extrusion
1.13 ± 0.20b
rate (g/min)

60

Observation Under extrusion Under extrusion Under extrusion

Extrusion
1.20 ± 0.10a
rate (g/min)

80

Observation Under extrusion Under extrusion Under extrusion

1.22 mm Extrusion
1.23 ± 0.23b
rate (g/min)

100

Observation Under extrusion Under extrusion Under extrusion

Extrusion
0.7 ± 0.20a
rate (g/min)

PEC 20 Not printable

Table 4.2. Optimization of hot-extrusion 3D printing condition of the material supplies

62
4.3. Quality of 3D printed gummies

In most cases, the color of a food product and, therefore, its visual appearance critically

decide

its consumer acceptability. Similarly, in the case of gummies, their texture is a key parameter.

The optimized printing conditions from the previous steps (temperature: 80 °C, printing

speed: 800 mm/min; nozzle diameter 1.22 mm), the gummies were prepared, and the printed

gummies' textural and color characteristics were assessed. Printed gummies have a hardness

of 70.19 ± 3.66 g, adhesiveness of -21.35 ± 1.18 g.s, springiness of 0.52 ± 0.03, cohesiveness

of 0.42 ± 0.04, gumminess of 29.58 ± 1.69, chewiness of 15.46 ± 1.79, and resilience of 0.08

± 0.00. These textural values are comparable with the previous study [25]. Similarly, the

color values such as lightness (34.62), redness (0.91), and yellowness (21.04) were observed.

4.4. Sensory evaluation

4.4.1. Visual sensory

The visual appeal of 3D-printed watermelon rind gummies was evaluated through sensory

analysis. Under the optimized printing conditions, either of the three different colors (red,

green, yellow) under permissible limits were added to the material supply. Fig. 4 illustrates

the visual sensory results in terms of all the parameters; red color gummies were ranked

higher by the panelists. Green gummies followed in terms of color and other parameters for

acceptance. An overall acceptance score of 7.8 was observed for the red gummies. Typically,

for commercial applications, different colors and shapes can be mixed in a single pack.

63
 Fig. 8. Visual sensory profiles of 3D printed gummies (Right side images representing the

different color 3D printed gummies)

4.4.2. Product sensory

This sensory analysis compares the 3D-printed gummies with a commercial (non-watermelon

rind-based) counterpart, evaluating key attributes like appearance, color, aroma, taste, texture,

and overall acceptability (Fig. 5). The panelists found the aroma of the control sample to be

more appealing than the 3D printed gummies. However, there were no significant differences

in the taste of the control and printed gummies and the printed gummies was ranked higher.

The texture of the 3D-printed gummy was slightly more preferred than the commercial

gummy. The unique textural properties resulting from the 3D printing process contributed to

this preference. In overall acceptability, the 3D-printed gummy scored slightly higher (7.3)

than the commercial gummy (6.96). With unlimited customization prospects, 3D printing can

64
be used to develop different formulations based on consumer-specific requirements and

consumer preference-based decisions.

Fig. 9. Sensory profile comparison of commercial and 3D printed gummies

4.5. Proximate analysis

4.5.1. Moisture content

Moisture content is a critical factor influencing the properties of food materials. Analysis

revealed distinct differences across the samples: watermelon rind exhibited a high moisture

content of 91.17 ± 0.61 % consistent with its nature as a water-rich fruit component. The

material supply showed 39.10 ± 1.49 % moisture optimized for the printing process; and the

printed gummies showed a reduced moisture level of 23.7 ± 1.44 %, indicating potential

moisture loss during printing due to factors like heat exposure or evaporation, which could

impact texture and shelf life.

Sample Moisture content (%wb)

Watermelon rind puree 91.17 ± 0.61

65
 Material supply 39.10 ± 1.49

Printed gummies 23.7 ± 1.44

Table 4.5.1. Moisture content of samples

4.5.2. Protein content

Sample Protein content (%)

Watermelon rind puree 0.77 ± 0.01

Material supply 0.52 ± 0.01

Printed gummies 0.46 ± 0.05

Protein is an essential factor for human life but food sources like fruits, vegetables, and

cereals do not contain much protein. Also when compared to processed products, raw

materials have higher protein content. Likewise, the protein content in the watermelon rind

(0.77 ± 0.01 %) is low but higher than the protein content of material supply ( 0.525 ± 0.01

%) and printed gummies ( 0.46 ± 0.05 %). The decrease in protein content in printed

gummies may be influenced by heat exposure during printing.

Table 4.5.2. Protein content of samples

4.5.3. Fat content

Fat content analysis is essential for nutritional labelling, dietary guidance, and understanding

food's energy value and sensory properties. The fat content is low in all samples but shows a

slight increase from the rind to the material supply, due to the addition of other ingredients in

the material supply. The fat content in material supply and printed gummies exhibit similar

values. The average fat content value of the triplicate reading in the watermelon rind is 1.51 ±

0.11 %, in material supply is 1.73 ± 0.56 %, and in printed gummies is 1.76 ± 0.03 %.

66
 Sample Fat content (%)

Watermelon rind puree 1.51 ± 0.11

Material supply 1.73 ± 0.56

Printed gummies 1.76 ± 0.03

Table 4.5.3. Fat content of samples

4.5.4. Crude fiber

Sample Crude fiber (%)

Watermelon rind puree 4.73 ± 0.40

Material supply 0.90 ± 0.10

Printed gummies 0.97 ± 0.20

The watermelon rind is a significant source of fiber. The initial fiber content in the

watermelon rind was measured at 4.73 ± 0.40 %, a value typical of many fruits and

vegetables. However, this value dropped significantly to 0.90 ± 0.1 % in the material supply

and 0.97 ± 0.20 % in printed gummies, indicating a considerable loss of fiber. This reduction

is likely attributable to a combination of factors, including the lower percentage of

watermelon rind present in the material supply, effectively diluting the fiber concentration,

and adding other ingredients like sugar and pectin, which are devoid of fiber.

Table 4.5.4. Crude fiber of samples

4.5.5. Total ash

The total ash content represents the total inorganic minerals present in the sample. The

watermelon rind exhibited an ash content of 0.38 ± 0.14 %, a usual range of plant-based

material. A slight increase in ash content in the material supply 0.56 ± 0.12 % was observed.

67
It is because of the reduction of moisture and the addition of other ingredients such as sugar

pectin, and citric acid.

Sample Ash content (%)

Watermelon rind puree 0.38 ± 0.14

Material supply 0.56 ± 0.10

Printed gummies 0.51 ± 0.07

The ash content in the printed gummies 0.51 ± 0.07 % is similar to the material supply ash

content. This indicates that the mineral contribution from the watermelon rind and the

gummy is low.

Table 4.5.5. Total ash content of samples

4.5.6. Carbohydrate and energy

The estimated amount of carbohydrates present in the samples are tabulated below in the

amount of carbs is directly proportional to the energy value. The watermelon rind exhibits a

very low carbohydrate value of 1.44 ± 0.38 % as the rind is mostly composed of water. The

carbohydrate in the material supply is 57.17 ± 1.95 %, which is due to the addition of pectin

and sugar. The slight increase in carbohydrates in printed gummies of 72.4 ± 1.21 is the result

of loss of moisture during the hot extrusion printing.

Sample Carbohydrate (%) Energy (Kcal/g)

Watermelon rind puree 1.44 ± 0.38 22.28 ± 1.26

Material supply 57.17 ± 1.95 246.41 ± 3.84

Printed gummies 72.4 ± 1.21 308.64 ± 5.85

Table 4.5.6. Carbohydrate content of samples

68
 Summary and conclusion

CHAPTER - V

5. Summary and conclusion

69
 In conclusion, this study demonstrates a novel application of waste valorization

through 3D printing, utilizing watermelon rind to create vegan gummies. Typically, apart

from its scope in being marketed as gummies, the approach can be extended to the delivery of

nutraceutical ingredients or others, as required for specific applications. The hot extrusion 3D

food printing technique is employed to make watermelon rind gummies based on High

Methoxyl pectin (HM-pectin). Initially, the gummies were made by optimizing the

concentration of rind puree (25, 30, 40, 50 % w/w). The material supply's printability was

optimized by taking varying pectin levels (0, 5, 10, 15 and 20% w/w). The impact of printing

parameters such as temperature (60, 80, and 100 °C), nozzle diameter (0.6, 0.84, and 1.22

mm), and printing speed (600, 800, and 1000 mm/min) was assessed. The optimization and

characterization of the material revealed that its textural, rheological, and thermal properties

are crucial in predicting printability and achieving successful prints. Among the tested rind

puree concentrations, the formulation containing 25% rind puree was suitable for the method.

Likewise among the pectin concentration, 10% provided the best mechanical strength,

textural qualities, and melting behavior, significantly influencing the printing parameters. By

incorporating HM-pectin into watermelon rind puree, the material was rendered printable,

with optimized 3D printing conditions established at a speed of 800 mm/min, using a 0.84-

mm nozzle at 80 °C, a motor speed of 60 rpm, and an extrusion pressure of 1.5 bar. Sensory

evaluations showed a clear preference for 3D-printed gummies over commercial ones. The

proximate analysis of watermelon rind puree, material supply, and printed gummies

highlighted their nutritional profile, where the composition of rind puree was predominantly

moisture. However, the composition of material supply and printed gummies showed a higher

concentration of carbohydrate content. A slight decrease in the moisture content in the printed

gummy was observed due to the evaporation of moisture during hot extrusion 3D pinting.

This work underscores the potential to transform unused or leftover edible components into

70
high-value food and other products, paving the way for sustainable processing and cleaner

production. As the first study to use watermelon rind for 3D food printing, it sets a foundation

for creating innovative, waste-derived customized and personalized foods with enhanced

consumer appeal.

71
6. Publications and conferences

• Keerthy, A. M., Dhanaselvam, K. R., Santhoshkumar, P., Ravikrishnan, V., & Moses,

J. A. (2024). Optimization of 3D printing conditions for the development of gummies

from watermelon rind waste. Food Biomacromolecules. (under review)

• Dhanaselvam K. R., Anandha Keerthy M., Santhoshkumar P., R. V., & Moses, J. A.

(2024). Pectin-based Vegan Gummies: A 3D Food Printing Approach to Valorize

Watermelon Rind. National Conference on Innovation, Entrepreneurship and Start-

Up Opportunities in Food & Dairy Sector.

• Anandha Keerthy M, Dhanaselvam K. R Santhoshkumar P., R. V., & Moses, J. A.

(2024). Development of watermelon rind-based 3D printed gummies. 30thIndian

Convention of Food Scientists & Technologists (ICFoST) “Food Safety, Standards,

Security and Sustainability” ‘FoodSSSS.’)

72
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APPENDICES

Problems in rind processing

The rind slices were planned to be dried using a hot air oven at 60°C for 24 hours and

pulverized into fine powder for the incorporation of watermelon rind powder in gummies.

However, it didn’t go well because the dried rind powder is highly hydrophilic and it tends to

absorb more moisture, which made the composition of the materials difficult to formulate.

The drying of the rind took 24 hours and after drying it was difficult to scrap the dried layers

from the oven. So, the rind slices were made into a fine paste with the help of a mixer

grinder. but it was too a failure that after drying the dried paste stuck together with the plates

of the oven which didn’t scrape out from it.

Fig .10 Dried rind paste in oven tray

Moulding method

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 Initially, this watermelon rind gummy formulation was obtained in the moulding

method. It took 10 - 15 mins to solidify. The ingredients composition was different for the

moulding method.

Ingredients Amount (g/100g)

1. Pectin 2

2. Sugar 50

3. Watermelon rind puree 25

4. Citric acid 0.5

5. water 27.5

Method of preparation

The sugar was made into syrup in a pan using water, after the syrup reached its

boiling point added pectin and stirred vigorously. Then followed by the addition of

watermelon rind puree, when it reaches a TSS of 75° brix add citric acid and stir

continuously. After a few seconds from the addition of citric acid, the mixture was poured

into moulds and let for 10 - 15 minutes to fully solidify

Variation in types of pectin

There were two preliminary trials conducted with two types of pectin, 1. HM pectin

and 2. LM pectin. The gummies made with LM pectin fig.11 (a) exhibited a soft texture that

didn’t feel like actual gummies but more like jelly. Then the gummies made with HM pectin

fig.11 (b) showed better results in the textural aspect like a hard and firm texture which can

said to be a gummy.

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 fig. 11 (a) fig. 11 (b)

Form of rind puree incorporation

The incorporation of the rind puree was taken in two ways, one is incorporating

concentrated rind puree using double boiling method and another way is just incorporating

the raw paste obtained from the grinding of blanched rind slices. The concentrated puree

incorporated gummy showed a bitter taste and harder texture which made the mixture hardly

pourable into the mould. On the other hand, the normal puree incorporated gummy showed a

well-firmed texture and a good taste rather than the previous.

Concentrated puree gummy Normal puree gummy

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