Microorganisms and enzymes play an important role in food preservation by extending shelf life. Lactic acid bacteria are commonly used to ferment dairy products and meats through the production of lactic acid, which prevents spoilage. Enzymes also contribute to food processing, with amylase breaking down starches and pectinase used in the coffee industry. Recently, genetic engineering has helped enhance the production of microbial enzymes for various food applications.

1. Role of Microorganism and
Enzymes in Food Preservation
Pallavi Wani
I Ph.D. (Hort.)
Dept. of Horticulture
GKVK, UAS Bengaluru

2. Food preservation is a process in which
Fruits and vegetables are prevented from getting spoilt
The color, taste, and nutritive values of food is also preserved
Food products lasts for a long period of time: shelf life of food
product is increased
Food preservation ?

6. Microorganisms are an important part of the food industry as these
are helpful in food preservation and production.
Usually, microorganisms are used in making dairy products
(yogurt and cheese), fermented vegetables (olives, pickles, and
sauerkraut), fermented meats (salami), and sourdough bread.
These are also utilized for the production of wine and several
other beverages.
Recently in the food industry, the use of microorganisms has
started on a large scale for the production of chocolate, food color,
from preserving fruits, vegetables and meat, and as probiotics
which are helpful for human health.

7. Microorganisms contribute to the smell, texture and taste of the food
For example, bacteria are Lactobacilli that is used for the production of food
as these bacteria ferment lactic acid
Lactobacilli are conventionally used to add aroma and texture to the food
while preventing the spoilage of dairy products, meat and vegetables as well as
silage.
Microorganisms that are present in the GI tract are known for producing health
promoting compounds that are called probiotics
These probiotics in fermented products help in the preservation of milk
products through the formation of lactic acid which adds to the flavor as well as
nutritional value of the food

8. The role of different types of microorganisms in various food processes
SI.No Microbial Activity Microbes Use in industry
1 Pectinolytic activity Lactobacillus brevis ,Erwinia
herbicola
Cofee industry
2 Naringinase activity Aspergillus niger, Aspergillus
oryzae,
Fruit juices industry
3 Fermentation Streptococcus thermophilus and
Lactobacillus bulgaricus
Dairy industry
4 Protease activity Bacillus tequilensis Brewing industry
5 Asparaginase
activity
Cladosporium sp Baking industry

9. 1. Role of Lactic Acid Bacteria
Lactic acid bacteria are being used in a number of food production and
storage methods in the modern food industries.
Lactobacilli are commonly used for the storage of uncooked fermented
sausages and sliced meats to avoid pathogenic
These bacteria have replaced the chemical additives such as sodium lactate
and potassium acetate which were used for the safety and quality
Mechanism- of action of lactic acid bacteria in raw fermented sausages is the
conversion of sugars to lactic acid through fermentation. This contributes to the
unfavorable conditions for the growth of pathogenic and spoilage
microorganism.
Lactobacillus spp. that is frequently used in baking industry to improve softness
and texture of baked products such as breads
Int. J. Innovations in Sci. & Tech., Hussain et al., 2021

10. 2. Role of Microbial Transglutaminase
Transglutaminase is an enzyme that is involved in the catalysis of acyl- transfer
reactions between proteins, peptides and amines .
Generally, transglutaminase is found in plant and animal tissues
Transglutaminases are commonly used in fish products such as Japanese fish
paste.
Transglutaminase also has the ability to maintain the freshness of vegetables
and fruits when a coat of transglutaminase is applied to them.
One such study showed that when cut celery was coated with transglutaminase,
it not only preserved the freshness of celery but also reduced the bacterial
growth
It also improves the pore size and elasticity of the baked bread which in turn
increases the shelf life of the bread
Hussain et al., 2021

11. 3. Microorganisms and Chocolate Production
Researches showed that raw cocoa is rich in antioxidants which are also present
in vegetables and tea.
These antioxidants not only provide defense against cancer causing reactive
oxygen species but also prevent oxidation of LDL-cholesterol .
 The role of microorganisms is to enhance the flavor of chocolate through
fermentation when the pod of the cocoa bean is opened which leads to a less
astringent and bitter taste of the chocolate.
There are two types of fermentation taking place during the production of chocolate
from raw cacao beans.
First, the alcoholic fermentation that is mediated by the yeast which kills the bean and
enhances the flavor of chocolate by converting sugar into alcohol.
 The second fermentation is acetic acid fermentation in which alcohol is oxidized and
acetic acid is produced which overall improves the texture, aroma, flavor and color of
the chocolate

12. 4. Microorganisms used in the production of Biocolors
Colors that are used in foodstuff, dyes, cosmetics and other industries are usually
synthetic and possess toxic properties
Various types of microorganisms including fungi, algae and yeasts are colored in nature
and their color can be extracted for industrial purposes. Currently, fungi are considered as
an important source of biocolors
Species belonging to Monascus genus of fungi produce three different pigments
including orange, red and yellow. These pigments are commonly used in East Asian
foods such as red rice wine and red bean curd
Other than fungi, Bacillus sp. produces riboflavin that are rich in yellow orange
pigment and currently being used in baby foods, cheese, pasta sauce and cereals.
Hussain et al., 2021

13. 5. Microorganisms as Probiotic
Probiotics are made of both bacteria and yeast.
Probiotics are currently of great interest in industries such as food,
medicine and dietary supplements
Dairy drinks are the first rich source of probiotics and are also
called fortified dairy products.
Yogurt is considered the natural source of probiotics as it is
produced by Lactobacillus and Streptococcus species.
Other than dairy products, there is also a demand for the use of
probiotics in vegetables and fruit juices
Hussain et al., 2021

14. 6. Role of microorganisms in the processing and preservation of
Meat
As described earlier, Lactic acid bacteria are primarily used in
preservation of meat products.
The main mechanism of action of these bacteria is to produce
lactic acid and acetic acid through fermentation that lowers the pH
of the meat product.
 This leads to the preservative effect that is desired to be
achieved
Hussain et al., 2021

15. 7. Role of microorganisms in Nisin Activity
Nisin is a bacteriocin produced by Lactococcus lactis
Nisin has the ability to prevent the growth and spore formation of
many of the gram positive and gram negative bacteria
Nisin is commonly used to preserve foods that are low acid
canned foods as neutral or near to neutral pH facilitates the growth
of spoilage and pathogenic bacteria
Hussain et al., 2021

16. Role of Nisin in food industry
Hussain et al., 2021

17. 8. Role of microorganisms in increasing Antioxidant activity
Antioxidants are a group of chemical compounds that inhibit or
delay the process of oxidation and ultimately help in prevention of
cell damage
Commonly used antioxidants are carotenoids such as Beta
carotene, lycopene
Lately, use of antioxidants have gained importance in nutrition and food
industry because it not only increase the shelf life of food while maintaining
nutritional quality but also reduces the oxidative damage to the consumer’s
body

19. Enzymes are organic biocatalysts which govern, initiate and control
biological reactions important for life processes.
1. Amylase--- Promotes digestion or breakdown of starch in mouth
(Saliva)
2. Pepsin ------Digestion of Protein
(Gastric Juice)
3. Lipase-----Promotes breakdown of fat
(Liver)
Foods contain a great amount of active enzymes.
All enzymes are proteins but all proteins are not enzymes.

20. Important properties of enzymes in fruit and vegetable
technology
Enzymes controls the reactions associated with ripening of fruits
and vegetables
After harvest, unless destroyed by heat, chemicals or some other
means, enzymes contribute the ripening process, in many cases to
the point of spoilage such as soft melons or overripe banana
Because enzymes enter into a number of biochemical reactions in
fruits and vegetables, they may be responsible for changes in flavor,
color, texture and nutritional properties.
The heating processes in fruits and vegetables processing are
designed not only to destroy microorganism but also deactivate
enzymes and so improve the fruits and vegetables storage stability.

21. In fruit and vegetable storage and processing the most important
roles are played by the enzymes classes of
 I. Hydrolases (lipase, invertase, tannase, amylase, cellulase) and
 II. oxidoreductases (peroxidase, tyrosine, catalase,
polyphneoloxidase
Enzymes are being increasingly used for the preservation and
processing of a wide variety of foods and beverages.

22. Enzymes used in the food industry
Enzymes Class Source Application
Amylase Hydrolases Malt, Fungi Bread baking
Cellulase Hydrolases Fungi, Bacteria Foods
Glucose
Isomerase
Isomerases Fungi, actinimyctes Sugar and Starch
Invertase Hydrolases Yeast Candies
Lactase Hydrolases Bacteria Milk ,ice cream
Pectinase Hydrolases Fungi Coffe bean
Rennin Lyases Fungi Cheese production

23. Immobilized enzymes- “Enzymes physically confined or localized in a certain
defined region of space with retention of their activity and which can be used
repeatedly and continuously.”
Advantages-
Recovery and reuse of enzyme is possible
Stability of enzyme is increased
Minimized reaction time
Less labour input
Permit continues opertaion
Cost is lower,
Immobilized enzymes are presently being used to hydrolyze the lactose of milk
into glucose and galactose,
To isomerize the glucose from corn to starch into fructose, and
Many industrial food processes

24. Genetic Engineering of Microorganisms for
Enhanced
Enzyme Production
Microbial Enzymes in Food Applications
Nowadays, genetic engineering has become a very useful tool to increase
the production of enzymes as it is more cost-effective and also to obtain
enzymes better adapted to the conditions used in modern food production
methods.
Alternatively, they can be expressed on filamentous fungi and yeasts.
The genetic engineering technologies like recombinant DNA technology,
protoplast fusion and mutation are commonly used for the enhanced
production of enzymes.
Mishra et al., 2018

25. • It is concluded that there is need to focus useful microbes for the welfare of
mankind to increase the food production.
• A number of microbial functions such as preservation, quality enhancement
of food products, antioxidant properties and usage as a probiotics makes
them best both for human and environment.
• Subsequent developments of enzyme production technology for application
in food processing
• Now with the growing population and increased demand for food, microbial
enzymes and industrial production of food has acquired utmost importance
• Genetic manipulation through recombinant DNA technology, protoplast fusion
and mutation has been proved to be useful for improved production of food
enzymes
CONCLUSION