International Food Research Journal 22(6): 2230-2236 (2015)

Journal homepage: http://www.ifrj.upm.edu.my

Edible films from seaweed (Kappaphycus alvarezii)

1*
Siah, W.M., 2Aminah, A. and 2Ishak, A.
1
Food Technology Research Centre, Malaysian Agricultural Research and Development Institute,
P.O. Box 12301, General Post Office, 50774 Kuala Lumpur, Malaysia
2
School of Chemical Sciences and Food Technology, Faculty Science & Technology, Universiti
Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

Article history Abstract

Received: 18 April 2014 A new patent pending process is proposed in this study to produce edible film directly from
Received in revised form: seaweed (Kappaphycus alvarezii). Seaweed together with other ingredients has been used to
8 May 2015 produce the film through casting technique. Physical and mechanical tests were performed
Accepted: 25 May 2015
on the edible films to examine the thickness, colour, transparency, solubility, tensile strength,
elongation at break, water permeability rate, oxygen permeability rate and surface morphology.
Keywords
Produced film was transparent, stretchable, sealable and have basic properties as a film for food
packaging. This study suggests that the edible film could be used as novel materials in food
Edible film industry as sachet/pouch/bag for instant coffee, breakfast cereals drinks, seasoning powder,
Seaweed candies etc; as wrapper for seasoning cube and chocolate; as interleaf for frozen foods such as
Kappaphycus alvarezii burger patties to avoid the patties from sticking together; and also as material for edible logo in
Characterization bakeries products. Other than that, the edible film also could be used in pharmaceutical industry
Applications as functional strips such as oral freshener strips and drug strips. In cosmetic and toiletries
industries, the edible film could be used to produce facial mask and bag for pre-portioned
detergent. Compared with edible film developed earlier using alginate and carrageenan, film
developed in this research used seaweed directly. The developed film reduced the need to
extract the alginate and carrageenan, making material preparation easier and cheaper.

© All Rights Reserved

Introduction research is still on the preliminary stage in Malaysia.

This paper was focused on the development of edible
Plastic products have become an integral part seaweed based films for application especially in
in our daily life as a basic need. Its broad range of food industry, pharmaceutical industry, cosmetics
application is in packaging films, wrapping materials, and toiletries industries.
shopping and garbage bags, fluid containers, clothing, Seaweed is sustainable natural resources
toys, household and industrial products, as well as with industrial potential that is not fully utilized.
building materials. Once plastic is discarded after its The farming of seaweed has expanded rapidly in
utility is over, it is known as plastic waste. Only small Malaysia, especially Sabah, is one of the seaweed
percentages of this plastic waste are recycled and producers in the world with total production in year
mostly will be ends up in landfills, beaches, rivers 2010 was 150,000 MT and expected to produce
and oceans. It is a fact that plastics will never degrade 1,500,000 MT by 2020 (Tan et al., 2011). Under
and remains on landscape for several years and the Economic Transformation Programme (ETP),
subsequently raises environmental issues. Therefore, the Federal Government has approved substantial
a small reduction in the amount of plastic materials amount of fund to uplift the industry to be one of
will reduce environmental concerns. Development of the economic resources for the country and creating
edible and biodegradable material to partially replace more employment opportunities. Hence, research
petro-based polymers may offer opportunities that and development programme was needed to support
would benefit both manufacturers and consumers. the industry. Through this project, the development
To meet the growing demand of degradable and of edible seaweed based film is a promising method
natural materials, new materials and technologies for diversifying the usage and adding value to the
have been extensively studied including using bio- seaweed.
based polymers. Bioplastic or biopolymer products Seaweed derivatives such as alginate and
can be made from raw materials originating from carrageenan have been widely used to form edible
agricultural or marine sources. However, this kind of films and their barrier and mechanical properties

*Corresponding author.
Email: wmsiah@mardi.gov.my
Tel: 03-8941 6896; Fax: 03-8942 2906
2231 Siah et al./IFRJ 22(6): 2230-2236

have been studied (Pranoto et al., 2005; Maria et temperature (23oC and 45% RH) and expressed as an
al., 2007; Maria et al., 2008; Maizura et al., 2007; average of 10 random measurements.
Maizura et al., 2008; Alicia et al., 2009; Mariana et
al., 2009; Fazilah et al., 2011; Song et al.; 2011). Measurements of colour
However, on another aspect, the possibility to form Colour was measured using a Chroma Meter
film directly from seaweed has not yet been explored. CR10 (Minolta Camera Co. Ltd., Osaka Japan) based
Since seaweed mainly consists of protein and non- on the CIE L*a*b* colour system, where L* describes
starch polysaccharides (Dawczyski et al., 2007), lightness (ranging from black to white), a* and b*
these compounds might possibly provide sufficient describe the chromatic coordinates (ranging from –a:
properties to form edible film and packages. This greenness, –b: blueness, +a: redness, +b: yellowness).
film would reduce the need to isolate the alginate Film specimens were placed on the surface of a white
and carrageenan, making material preparation easier standard plate (L*=92.1, a*=2.1, b*=-9.2. A mean
and cheaper. Therefore, the objectives of this paper value of 10 measurements was reported for each color
are to develop edible film directly from seaweed attribute. Colour differences (ΔE) was calculated by
(Kappaphycus alvarezii) and to determine the the following equation:
characteristics of the developed edible film and at the
same time to study its potential applications. ΔE = √ (L* - L)2(a* - a)2(b*- b)2

Materials and Methods Where L*, a* and b* are the colour parameter values
of the standard and L, a and b are colour parameter
Sample preparation values of the sample.
Dried seaweed (Kappaphycus alvarezii) was
obtained from Semporna, Sabah Malaysia. The Measurements of transparency
seaweed was washed under running water to The light barrier properties of the films were
remove debris and salt before being soaked. The measured by exposing the films to light absorption
seaweed edible film was processed according to the at wavelength 600 nm. Film transparency was
steps outlined in patent pending invention titled: measured according to the method of Bao et al.
Biodegradable Food Film From Seaweed And (2009) by placing rectangular film samples into a
Process For Producing The Same (PI2013003883). spectrophotometer test cell directly. This method was
Films were prepared using solvent casting method modified from the ASTM method D1746, which is
by casting film forming solution on the fabricated the standard test method for transparency of plastic
casting plates and subsequently dried. After drying, sheeting (ASTM, 2009). Absorbance was recorded
the films were peeled off. using an UV/Vis Spectrophotometer (Optizen
2120UV, Korea). The transparency (T) of films was
Characterization of edible film calculated according to the following equation:

Conditioning T = A600/x
Films were conditioned prior subjecting to
permeability and mechanical tests according to the where A600 is the absorbance at 600 nm and x is
Standard Method D618-61 (ASTM, 1993). Films the film thickness (mm). According to this equation,
were conditioned at 53% RH and 27 ±2oC by placing a higher value of T would indicate a lower degree
them in desiccators over a saturated solution of of transparency. Tests were run in triplicates for each
Mg(NO3)2.6H2O for at least 72 hours. These films type of film.
were used for water vapour permeability test (WVP),
oxygen permeability test (OP), Tensile Strength (TS) Solubility of edible films
and Elongation At Break (EAB). For other tests, The solubility of the films was determined
films were transferred to plastic bags after peeling according to method by Romero-Bastida et al.
and placed in desiccators. (2005) with minor modification. The film solubility
(S%) expresses the percentage of film’s dry matter
Measurements of thickness solubilized after immersion of pre-weighted films (2
A digital micrometer (Model DM 3025; Digital x 3 cm) in 80 ml of deionized water for 30 minutes
Micrometers Ltd., Sheffield UK) was used to at 25oC with constant agitation. The remained pieces
measure the film thickness to the nearest 0.001 of film after immersion filtered using filter paper
mm. Thickness of each film was measured at room (Whatman No 1) were dried at 600C in an oven to
 Siah et al./IFRJ 22(6): 2230-2236 2232

constant weight. Film solubility (S%) was calculated pressure and multiplying by the mean thickness.
from the following equation:
Surface morphology
Solubility (%) = (Initial dry weight – Final dry Film samples were examined for surface
weight) / Initial dry weight x 100 characteristics using a JEOL JSM-6400 scanning
electron microscope (JOEL Ltd., Tokyo, Japan)
Measurements of mechanical properties operated at 15 kV. Five samples were mounted on a
The procedure used to prepare the films for bronze stub and sputter-coated (Sputter Coater Bal-
testing of mechanical properties was adapted from tec SCD 005, Liechtenstein) with a layer of gold
ASTM standard test method for tensile properties of prior to imaging in order to increase their electrical
thin plastic sheeting (ASTM, 2001). Film samples conductivity. Images were registered at 500 x
were cut into 120 mm x 10 mm dumb bell strips magnification.
and thickness of the individual specimens was
determined as a means of five measurements taken Results and Discussion
over the gage length. It was then used to estimate
the cross-sectional area. The tensile properties were Characterization of edible film
determined using a TA-HDi Texture Analyzer (Stable The physical and mechanical properties of
Micro Systems Ltd. Surrey, England) with a load cell the edible film are shown in Table 1. The film
of 25 kg and crosshead speed of 1.0 mm/sec. Film was easily removed from the fabricated casting
samples were clamped between grips, leaving an plate. The developed film was transparent with the
initial distance between the grips of 75 mm. Tensile thickness of 0.076 mm. The colour of the film is an
Strength (MPa) was calculated by dividing the important attribute which influences its appearance,
maximum load (N) necessary to pull the sample film marketability and their suitability for various
apart by the cross-sectional area (m2). Percentage of applications. Clear edible films are typically desirable
elongation at break was calculated by dividing film (Sivarooban et al., 2008). Visually, the edible film
elongation at the moment of rupture by the initial grip had a slightly yellow appearance with total colour
length of samples multiplied by 100%. A total of 10 difference (ΔE) value of 4.84.
samples were tested for each film type. Transparency is one of the common optical
properties of light permeable materials.
Measurements of water vapour permeability (WVP) Spectrophotometer is used to measure the
Water vapor permeability values (WVP) were transparency of a material by light-transmittance or
measured using a modified ASTM method (ASTM, absorbance. Development of transparent packaging
1989) reported by Gontard et al. (1992). The film was materials which allow product visibility is a general
sealed in a glass permeation cup containing silica gel trend and requirement in packaging films. The edible
(0% RH) with silicone vacuum grease and an “O” seaweed film has a transparency of 4.94 indicating
ring to hold the film in place. Silica gels were heated at that the film was fairly transparent. Data obtained in
180°C for at least 3 h prior to use for the determination. this study indicated that the transparency of seaweed
The cups were placed in desiccators with distilled film was relatively close to synthetic polymer films,
water at 30°C. The cups were weighed at intervals of polyvinylidene chloride (PVDC) (Yusuke et al.,
1 h over a 12 h period and WVP (g•m-1• s-1•Pa-1) of 2004) with transparency of 4.58, thus the film are
the film was calculated as follows: WVP=(w• x)/A clear enough to be used as see-through packaging
• t • (P2–P1) (McHugh et al., 1993), where w is the material.
weight gain of the cup (g), x is the film thickness Solubility is an important property for
(mm), A is the area of exposed films (m2), t is the biodegradable and edible film applications. Film
time of gain (s), and (P2–P1) is the vapor pressure solubility can be view as a measure of the water
differential across the film (Pa). resistance and integrity of a film (Rhim et al., 2000).
Soluble film packaging is convenient to use in ready
Measurement of oxygen permeability to eat foods as they dissolved in boiled water or in
The oxygen transmission rates of films were the consumer’s mouth. 66.08% of the developed
determined using ASTM Standard Method D3985- edible film was dissolved in the tested conditions.
05 (2010) with some modification. Mocon Oxtrans This reading was slightly higher than results for
2/21 at 0% RH and 23oC was tested on duplicated methycellulose films (Turhan and Sahbaz, 2004),
samples. The oxygen permeability was calculated methycellulose-chitosan films (Pinotti et al., 2007)
by dividing oxygen transmission rate by the oxygen and rice-chitosan films (Bourtoom and Chinnan,
2233 Siah et al./IFRJ 22(6): 2230-2236

Table 1. Properties of edible films

Figure 1. Scanning electron microscopy image (x 500) of

seaweed edible film

2008). barrier properties when comparing with wheat gluten

Biopolymer materials, such as edible films may films (24.26-39.67 cm3µm/m2day.kPa) (Patricia and
be subjected to various kinds of stress during use. Carlos, 2003) and zein films (13.0-44.9 cm3µm/
Analyzing the mechanical properties of an edible m2day.kPa) developed by Park and Chinnan (1990).
film is relevant in order to predict its behavior when The edible films should be uniform and free
it has been applied to a food product. Tensile strength from defects for their functionalities. During the
and elongation at break are very useful parameters film-forming process, shrinkage of the films due to
for describing the mechanical properties of a film, evaporation of water or rapid drying often causes
and are closely related with its internal structure defects such as cracks or curling in the films (Obara
(Mc Hugh and Krochta, 1994). Tensile strength is and McGinity, 1995). A scanning electron microscopy
the maximum tensile stress sustained by the sample (SEM) was used to determine the surface morphology
during the tension test. If maximum tensile stress of edible seaweed film. It was observed that the film
occurs at either the yield point or the breaking point, showed homogeneous, uniform and continuous
it is designated tensile strength at yield or at break surface without cracks and porous structure (Figure
respectively. Elongation at break is an indication of 1). The homogeneous matrix of film is a good
a film’s flexibility and stretch ability (extensibility). indicator of its structure integrity, and consequently
This is determined as the point when the film break good mechanical properties would be expected (Mali
under tensile testing. It is express as the percentage et al., 2002).
of change of the original length of the specimen
between the grips used to stretch the film (Gontard et Potential areas of applications
al., 1992). The studied edible had tensile strength and The seaweed edible film showed the possible
elongation at break values of 6.82 MPa and 17.90% uses in various industries including food industry,
respectively. pharmaceutical industry, cosmetic and toiletries
The deterioration of food in packages depends industries and also agricultural industry.
on water transfer between the internal products and
the surroundings. The water barrier characteristics of Food industry
the packages are thus required (Natcharee and Sudip, Generally, powdered soup, dried vegetables
2011). In this study, the edible seaweed film had and other ingredients of precooked noodles and cup
water vapour permeability of 34.76 g.mm/m2.day. noodles, or instant coffee are packaged to maintain
kPa which was much lower than apple puree edible their qualities with either aluminum laminated plastic
film with reading of 168.96 g.mm/m2.day.kPa (Maria or various plastic films. These packages must be torn
et al., 2006). to remove the contents prior to cooking or pouring
Oxygen is the key factor that might cause hot water over it. This is not only troublesome, but
oxidation, which initialed several food changes such also caused the packages to end up in the land-fills,
as odour, colour, flavor and nutrients deterioration where they can be last forever and never degradable.
(Rungsinee and Natcharee, 2007). Thus, obtaining One solution to these problems is to package such
film with substantial oxygen barrier can help products with an edible film. The package can be
maintaining and extending food shelf life. The dissolve by cooking or simply pouring hot water
seaweed edible film had oxygen permeability rate over it, thus making it unnecessary to tear the
of 18.54 cm3µm/m2day.kPa which showed excellent package and the material can be eaten together with
 Siah et al./IFRJ 22(6): 2230-2236 2234

incorporated directly into the solution prior to the

film being cast. These active ingredients become
locked into the film matrix and remain stable until
consumption. Examples of active ingredients used
in film strips include ingredients for oral hygiene,
caffeine for alertness, nutrients and botanicals. The
film also can be used to produce drugs/medicines
strips, a water soluble edible film that can hold active
pharmaceutical ingredients. It can be taken without
water which is highly recommended for the people
who have difficulty in swallowing such as elderly
and little children. There is no worry of blocking the
airway (Figure 2).

Cosmetic/toiletries industry
The edible film can be used to form facial masks
and bags for pre-portioned washing powder where
there are no packaging materials need to be dispose
as the films will dissolve completely in water (Figure
2).

Agricultural industry
The edible films can be formed into bags for pre-
portioned fertilizer mainly targeted for used in home
gardening. A small bag of fertilizer can be applied
to each pot where the fertilizer will dissolve slowly
when in contact with moist soils or during watering.

Conclusion

This study has demonstrated the feasibility of

using seaweed directly to produce edible film instead
of using extracts of seaweed (agar, carrageenan
or alginate). The developed film was transparent,
flexible, sealable, dissolvable and had substantial
mechanical strength to withstand stress during
handling. The film could be used in food industry,
Figure 2. Application of edible films pharmaceutical industry, cosmetics and toiletries
the contents. In addition, this film can also be used industries as well as agricultural industry. The
as a wrapper for Malay’s traditional cakes such as development of this edible seaweed based film is a
“dodol”, “kuih ketayap” and “popiah”; cheese slices promising method for diversifying and value adding
and seasoning cube. This film can also be used as the usage of seaweed and at the same time reducing
interleaf between foods to avoid it from sticking to food packaging waste.
each other, especially for frozen food such as burger
patties and instant “roti canai”. The film can be used Acknowledgements
for printing of edible logo for decoration of cakes and
other bakery products (Figure 2). This study was supported by the Science Fund
Grant (06-03-08-SF0342) from the Ministry of
Pharmaceutical industry Science, Technology and Innovation, Malaysia
The market for flavored film strips has growth (MOSTI). The authors would like to thank Ms.
potential, especially in the breath film segment. Nazarifah Ibrahim from Food Technology Research
Incorporating active ingredients opens the door Centre, MARDI, for her technical assistance.
for expansion into new segments such as films
with health benefits. Active ingredients can be
2235 Siah et al./IFRJ 22(6): 2230-2236

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