S. No.

Topics

1 Aim

2 Introduction

3 Material required

4 Procedure

5 Observations and calculations

6 Louis Pasteur Theory

7 Main purposes of fermentation

8 Safety of fermented food

9 Risks of consuming fermented food

10 Types of fermentation

11 Advantages of fermentation

12 Bibliography
 AIM

To compare the rates of fermentation of the given sample of wheat flour,

gram flour, rice and potatoes.
 INTRODUCTION

Fermentation is a metabolic process serving for some microorganisms to get

energy through digestion of simple fermentable sugars, mostly glucose and
fructose. In bakery fermentation, the production of carbon dioxide (CO2) is
required as it serves for fluffing up the dough. The principle of rheological
apparatus, used for the evaluation of fermented dough properties during its
maturation, is the measurement of gaseous volume or pressure produced. The
purpose of fermentation is to bring dough to the optimum condition for baking.

Fermentation typically is the conversion of carbohydrates to alcohols and

carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof
, under anaerobic conditions. A more restricted definition of fermentation is the
chemical conversion of sugars into ethanol. The science of fermentation is
known as zymology. Fermentation usually implies that the action of
microorganisms is desirable, and the process is used to produce alcoholic
beverages such as wine, beer and cider. Fermentation is also employed in
preservation techniques to create lactic acid in sour foods such as sauerkrautis,
dry sausages, kimchi and yoghurt, or vinegar for use in pickling foods.

Wheat flour, gram flour, rice flour and potatoes contains starch as the major
constituent. Starch present in these food materials is first brought into solution
in the presence of enzyme diastase, starch undergo fermentation to give
maltose. Starch gives blue-violet colour with iodine whereas product of
fermentation starch do not give any characteristic colour. When the
fermentation is complete the reaction mixture stops giving blue-violet colour
with iodine solution. By comparing the time required for completion of
fermentation of equal amounts of different substances containing starch the
rates of fermentation can be compared. The enzyme diastase is obtained by

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germination of moist barley seeds in dark at 15 degree Celsius. When the
germination is complete the temperature is raised to 60 degree Celsius to stop
further growth. The seeds are crushed into water and filtered. The filtrate
contains enzyme diastase and called malt extract.

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 MATERIAL REQUIRED

 Conical flask
 Test tube
 Funnel
 Filter paper
 Water bath
 1%Iodine solution
 Yeast
 Wheat flour
 Gram flour
 Rice
 Potato
 Aqueous NaCl solution

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 PROCEDURE

 Take 5gms of wheat flour in 100 ml conical flask and 30 ml of distilled

water.
 Boil the contents of the flask for about 5 minutes.
 Filter the above contents after cooling, the filtrate obtained is wheat flour
extract.
 To the wheat flour extract taken in a conical flask, add 5 ml of 1% aq.
NaCl solution.
 Keep this flask in a water bath maintained at a temperature of 50-60
degree centigrade. Add 2 ml of malt extract.
 After 2 minutes take 2 drops of the reaction mixture and add to diluted
iodine solution.
 Repeat step 6 after every 2 minutes. When no bluish colour is produced
the fermentation is complete.
 Record the total time taken for completion of fermentation.
 Repeat the experiment with gram flour extract, rice extract, potato extract
and record the observations.

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 OBSERVATION AND CALCULATION

Time required for the fermentation----

Wheat flour -- 10 Hours

Gram flour -- 12.5 Hours

Rice -- 15 Hours

Potato -- 13 Hours

CONCLUSION

Rice takes maximum time for fermentation and wheat flour takes the minimum
time for fermentation.

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 LOUIS PASTEUR THEORY

Louis Pasteur (27 December 1822—28 December 1895) was a French chemist,
pharmacist and microbiologist renowned for his discoveries of the principles of
vaccination, microbial fermentation and pasteurization, the last of which was
named after him.
In biochemistry fermentation theory refers to the historical study of models of
natural fermentation processes, especially alcoholic and lactic acid
fermentation.
Louis Pasteur's interest in fermentation began when he noticed some remarkable
properties of amyl alcohol—a by-product of lactic acid and alcohol
fermentation—during his biochemical studies. In particular, Pasteur noted its
ability to rotate the plane of polarized light, and its asymmetric arrangement of
atoms. These behaviours were characteristic of organic compounds Pasteur had
previously examined, but also presented a hurdle to his own research about a
law of hemihedral correlation. Pasteur had previously been attempting to derive
connections between substances' chemical structures and external shape, and the
optically active amyl alcohol did not follow his expectations according to the
proposed law. Pasteur sought a reason for why there happened to be this
exception, and why such a chemical compound was generated during the
fermentation process in the first place. In a series of lectures later in 1860,
Pasteur attempted to link optical activity and molecular asymmetry to organic
origins of substances, asserting that no chemical processes were capable of
converting symmetric substances (inorganic) into asymmetric ones
(organic). Hence, the amyl alcohol observation provided some of the first
motivations for a biological explanation of fermentation.

In 1856, Pasteur was able to observe the microbes responsible for alcoholic
fermentation under a microscope, as a professor of science in the University of
Lille. According to a legend originating in the 1900 biography of Pasteur, one

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of his chemistry students—an owner of a beetroot alcohol factory in Lille—
sought aid from him after an unsuccessful year of brewing. Pasteur performed
experiments at the factory in observation of the fermentation process, noticing
that yeast globules became elongated after lactic acid was formed, but round
and full when alcohol was fermenting correctly.

In a different observation, Pasteur inspected particles originating on grapevines

under the microscope and revealed the presence of living cells. Leaving these
cells immersed in grape juice resulted in active alcoholic fermentation. This
observation provided evidence for ending the distinction between ‘artificial’
fermentation in wine and ‘true’ fermentation in yeast products. These
observations provided Pasteur with a working hypothesis for future
experiments.

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 MAIN PURPOSES OF FERMENTATION
Fermentation has multiple purposes. It is used for food production (like yogurt,
cheese and bread), producing alcoholic beverages and biofuels, and in various
other industrial applications like tanning leather and preparing antibiotics.

FOOD PRODUCTION: -

 Preservation:

Fermentation was historically used to preserve food, making it last

longer.

 Enhancement:

It can make food more nutritious , digestible and flavourful.

 Variety:

Fermentation creates a wide range of food products, including pickles,

sourdough bread and fermented vegetables.

 Health benefits:

Fermented foods, particularly those rich in probiotics, can improve

digestion, reduce cholesterol, and support the immune system.

OTHER PURPOSES: -

 Alcohol production:

Fermentation is essential in the production of alcoholic beverages like beer

and wine.

 Biofuel production:

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 Fermentation can be used to create biofuels, providing an alternative
energy source.

 Industrial Processes:

It is used in tanning leather, producing certain types of tea, and in the

manufacture of antibiotics.

 In essence, fermentation is a versatile process with a broad range of

purposes, from food preservation to biofuel production and
creation of variety of products with beneficial properties.

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 SAFETY OF FERMENTED FOOD
Fermented foods generally have a very good safety record even in the
developing world where the foods are manufactured by people without training
in microbiology or chemistry in unhygienic, contaminated environments. They
are consumed by millions of people every day in both developed and the
developing world.

And they have an excellent safety record. What is there about fermented foods
that contributes to safety? While fermented foods are themselves generally safe,
it should be noted that fermented foods by themselves do not solve the problems
of contaminated drinking water, environments heavily contaminated with
human waste, improper personal hygiene in food handlers, flies carrying disease
organisms, unfermented foods carrying food poisoning or human pathogens and
unfermented foods, even when cooked if handled or stored improperly. Also,
improperly fermented foods can be unsafe. However, application of the
principles that lead to the safety of fermented foods could lead to an
improvement in the overall quality and the nutritional value of the food supply,
reduction of nutritional diseases and greater resistance to intestinal and other
diseases in infants.

One of the reason of safety of fermented foods is acidic environment which

inhibits growth of pathogens.

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 RISKS OF CONSUMING FERMENTED FOOD
Fermentation, while beneficial for food preservation and enhancing flavour,
also carries potential risks, including foodborne illnesses, chemical hazards and
allergic reactions. Improperly fermented foods can harbour harmful bacteria or
produce toxins, leading to food poisoning.

Specific Risks: -

 Foodborne Illnesses:
If fermentation is not properly controlled, harmful bacteria may survive
and multiply, leading to food poisoning.
 Chemical Hazards:

Fermentation can produce biogenic amines that can cause allergic

reactions, headaches, or other discomforts in some individuals.

 Mycotoxins:

Some moulds, like those found in fermented grains or peanuts, produce

mycotoxins, which can be carcinogenic or cause other health problems.

 Allergies:

Fermented foods can trigger allergic reactions in individuals sensitive to

certain components like histamine or specific proteins.

 High salt content:

Some fermented foods, like pickles and cured meats, have high sodium
levels, which can be harmful to those with hypertension or other
cardiovascular conditions.

 Botulism:

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 Improperly fermented foods can harbor Clostridium botulinum, a bacteria
that produces a deadly toxin (botulinum).

 Ethyl Carbamate (Urethane):

Some studies have linked fermented foods to the presence of ethyl

carbamate, a potential carcinogen.

 Antibiotic Resistance:

Certain microbes in fermented foods may carry antibiotic resistance

genes, which could contribute to antibiotic resistance in humans.

 Infection from Probiotics:

In some cases, fermented foods containing live bacteria (probiotics) can

cause infections, especially in individuals with weakened immune
systems.

 Excess Sugar and Calories:

Fermented beverages like kombucha can contribute to excess sugar and

calorie intake, leading to bloating and gas.

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 TYPES OF FERMENTATION
Types of fermentation include lactic acid fermentation, alcohol
fermentation, acetic acid fermentation, and butyric acid
fermentation. These processes are widely used in the production of food,
beverages, and other industrial products.

Types of Fermentation:

 Lactic Acid Fermentation:

This process, often performed by bacteria, converts pyruvate (a product of

glycolysis) into lactic acid. It's used in the production of yogurt, sauerkraut,
and other fermented foods.

 Alcohol Fermentation:

Primarily conducted by yeast, this type of fermentation breaks down pyruvate

into ethanol and carbon dioxide. It's crucial in the production of beer, wine,
and biofuels.

 Acetic Acid Fermentation:

This process, involving bacteria like Acetobacter, converts ethanol into acetic
acid (vinegar).

 Butyric Acid Fermentation:

This fermentation, carried out by certain bacteria, produces butyric acid as a

primary end product.

 Solid State Fermentation (SSF):

This method involves the growth of microorganisms on a solid substrate, like

grains or rice, and is used for producing enzymes, biopesticides, and in
bioremediation.

 Submerged Fermentation (SmF):

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This technique utilizes a liquid substrate and is suitable for microbes that
require high moisture, often used in industrial manufacturing.

 Other Fermentation Types:

There are also various other fermentation processes, such as propionic acid
fermentation, which is used in the production of Swiss cheese, and
fermentation involving other microorganisms like bacteria and fungi.

Different types of Fermentation on the basis of the end product formed: -

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 ADVANTAGES OF FERMENTATION
Fermentation offers numerous advantages, including improving digestibility,
enhancing flavor, increasing shelf life, and boosting nutritional value of foods.
It also plays a crucial role in producing various products like yogurt, cheese,
and alcoholic beverages, and supports a healthy gut microbiome.

Food Preservation and Safety: -

 Extended Shelf Life:
Fermentation, especially lactic acid fermentation, creates an acidic
environment that inhibits the growth of spoilage bacteria, extending the
shelf life of food.
 Reduced pathogen growth:
The acidic environment and the production of antimicrobial compounds
by fermentation can also reduce the growth of harmful bacteria and
pathogens.

Improved Digestibility and Nutrition: -

 Enhanced nutrient bioavailability:

Fermentation can break down complex carbohydrates and proteins,

making them easier for the body to digest and absorb.

 Increased vitamin production:

Some fermentations, like those involving bacteria, can lead to the

production of additional vitamins.

 Reduced anti-nutrients:

Fermentation can help to reduce anti-nutrients like phytic acid, which can
hinder the absorption of certain minerals.

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Health Benefits: -

 Probiotic and prebiotic support:

Fermented foods are a good source of probiotics, beneficial bacteria that

support a healthy gut microbiome.

 Improved gut health:

A balanced gut microbiome, supported by fermented foods, can

contribute to better digestion, immune function, and overall well-being.

 Potential mental health benefits:

Emerging research suggests a link between the gut-brain axis, and a

healthy gut microbiome, potentially influenced by fermented foods, may
positively impact mental health.

Other Advantages: -

 Fermentation can be a cost effective and sustainable method of food

preservation and production, especially in developing countries.
 It can also be used to produce biofuels, like ethanol, from plant matter.

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 Advantages of fermentation :-

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 BIBLIOGRAPHY

 Scribd.com
 Wikipedia
 Gemini AI assistant
 Google.com

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