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77
1. Which different microbes are useful to us?
2. Which different products can be produced with the help of  
 microbes?
Applied Microbiology
 Branch of biology in which study of the enzymes related to some prokaryotes and 
eukaryotic microbes, proteins, applied genetics, molecular biology, etc. is performed; is 
called as applied microbiology. This study is used for the society and various products like 
food and medicines are produced on large scale with the help of microorganisms.
We use the fermentation process while conversion of milk into 
yoghurt. Which microbes are useful for this process?
Products
A. Dairy Products
 Since ancient days, milk is converted into various products for its preservation purpose. 
Ex. Cheese, butter, cream, kefir, yoghurt, etc. Water content and acidity of the milk changes 
during formation of these products and texture, taste and flavour is improved.
 These processes are performed on large scale with more skill. For production of most 
of the milk products, bacteria in milk itself are used; only cheese is produced with the help 
of fungi. Basic process for production of yoghurt, cheese and cream is same. Milk is 
pasteurized at the beginning to destroy unwanted microbes. It is then fermented with the 
help of lactobacilli. In this process, lactose sugar of the milk is converted into lactic acid 
and milk proteins are coagulated with the help of lactic acid. Besides, compounds with 
taste and flavour are also formed. Ex. Diacetyl has the flavour of butter.
Can you recall?
Can you recall?
Industrial microbiology 
 This science is related to commercial use of microbes in which various economic, 
social and environment related processes and products are included. Various microbial 
processes useful for this purpose are carried out. 
 Industrial Microbiology: main features
A. Various productions with the help of fermentation process. Ex. Bread, cheese, wine,   
 raw material for chemicals, enzymes, nutrients, medicines, etc.
B. Use of microbes for garbage management and pollution control.
7. Introduction to Microbiology 
Ø  Applied Microbiology    
Ø  Industrial Microbiology   
Ø  Products   
Page 2


77
1. Which different microbes are useful to us?
2. Which different products can be produced with the help of  
 microbes?
Applied Microbiology
 Branch of biology in which study of the enzymes related to some prokaryotes and 
eukaryotic microbes, proteins, applied genetics, molecular biology, etc. is performed; is 
called as applied microbiology. This study is used for the society and various products like 
food and medicines are produced on large scale with the help of microorganisms.
We use the fermentation process while conversion of milk into 
yoghurt. Which microbes are useful for this process?
Products
A. Dairy Products
 Since ancient days, milk is converted into various products for its preservation purpose. 
Ex. Cheese, butter, cream, kefir, yoghurt, etc. Water content and acidity of the milk changes 
during formation of these products and texture, taste and flavour is improved.
 These processes are performed on large scale with more skill. For production of most 
of the milk products, bacteria in milk itself are used; only cheese is produced with the help 
of fungi. Basic process for production of yoghurt, cheese and cream is same. Milk is 
pasteurized at the beginning to destroy unwanted microbes. It is then fermented with the 
help of lactobacilli. In this process, lactose sugar of the milk is converted into lactic acid 
and milk proteins are coagulated with the help of lactic acid. Besides, compounds with 
taste and flavour are also formed. Ex. Diacetyl has the flavour of butter.
Can you recall?
Can you recall?
Industrial microbiology 
 This science is related to commercial use of microbes in which various economic, 
social and environment related processes and products are included. Various microbial 
processes useful for this purpose are carried out. 
 Industrial Microbiology: main features
A. Various productions with the help of fermentation process. Ex. Bread, cheese, wine,   
 raw material for chemicals, enzymes, nutrients, medicines, etc.
B. Use of microbes for garbage management and pollution control.
7. Introduction to Microbiology 
Ø  Applied Microbiology    
Ø  Industrial Microbiology   
Ø  Products   
78
2. Yoghurt Products 
 Yoghurt is a milk product produced with the help of lactobacilli (inoculant). For 
maintaining the protein content, condensed milk powder is mixed with milk to be fermented 
for industrial production of yoghurt. Milk is boiled and once it cools to warm temperature, 
bacterial strains of Streptococcus thermophilus and Lactobacillus delbrueckii are added to it 
in 1:1 proportion. Lactic acid is formed due to Streptococcus that makes the proteins to gel out 
that gives dense consistency to the yoghurt. 
 Acetaldehyde like compounds are formed due to lactobacilli 
that gives characteristic taste to the yoghurt. Now a day, various 
fruit juices are mixed with yoghurt to impart different flavours. Ex. 
Strawberry yoghurt, banana yoghurt, etc. Shelf life of yoghurt and 
its probiotic properties can be improved by pasteurization.
3. Butter
 Two types of butter like sweet cream and cultured are produced 
on large scale. Microbes are used for production of cultured variety. 
4. Cheese production
 Cheese is produced on large scale from the abundantly available 
cow milk all over the world. First, chemical and microbiological 
tests of milk are performed. Some colours and microbes like 
Lactobacillus lactis, Lactobacillus cremoris, and Streptococcus 
thermophilus are mixed with milk. It imparts sourness to the milk. 
After this, to impart the dense texture, whey (water in yoghurt) needs 
to be removed. 
 An enzyme, rennet obtained from alimentary canal of cattle 
was being traditionally used earlier. However, an enzyme protease 
obtained from fungi is used at present to produce vegetarian cheese. 
 The whey is separated from yoghurt (which has some other 
uses). Then, process of production of cheese is started through steps 
Let’s think 
Do you know?
1.  Which different types of cheese are used in western food like  
     pizza, burger, sandwich, etc?
2. What is difference between those types of cheese?
 During industrial production of milk products, strict cleanliness and sterilization 
is essential as bacteria can be attacked by viruses. Hence, virus-resistant varieties of 
bacteria are developed. Recently, use of mutant varieties of bacteria has been increased. 
Artificially, some strains are developed that will help to avoid unnecessary steps / 
materials. 
 Freshly prepared cheese is always soft e.g. cottage cheese, cream cheese, mozzarella 
cheese. On storing for 3 to 12 months, semi-hard cheddar cheese is formed whereas after 
ripening for 12 – 18 months, very hard cheese called parmesan cheese is formed.
7.1 Cheese and Butter
like cutting the solid yoghurt into pieces, washing, rubbing, salting, and mixing of essential 
microbes, pigments and flavours. Then, cheese is pressed and cut in to pieces and stored for 
ripening. 
Page 3


77
1. Which different microbes are useful to us?
2. Which different products can be produced with the help of  
 microbes?
Applied Microbiology
 Branch of biology in which study of the enzymes related to some prokaryotes and 
eukaryotic microbes, proteins, applied genetics, molecular biology, etc. is performed; is 
called as applied microbiology. This study is used for the society and various products like 
food and medicines are produced on large scale with the help of microorganisms.
We use the fermentation process while conversion of milk into 
yoghurt. Which microbes are useful for this process?
Products
A. Dairy Products
 Since ancient days, milk is converted into various products for its preservation purpose. 
Ex. Cheese, butter, cream, kefir, yoghurt, etc. Water content and acidity of the milk changes 
during formation of these products and texture, taste and flavour is improved.
 These processes are performed on large scale with more skill. For production of most 
of the milk products, bacteria in milk itself are used; only cheese is produced with the help 
of fungi. Basic process for production of yoghurt, cheese and cream is same. Milk is 
pasteurized at the beginning to destroy unwanted microbes. It is then fermented with the 
help of lactobacilli. In this process, lactose sugar of the milk is converted into lactic acid 
and milk proteins are coagulated with the help of lactic acid. Besides, compounds with 
taste and flavour are also formed. Ex. Diacetyl has the flavour of butter.
Can you recall?
Can you recall?
Industrial microbiology 
 This science is related to commercial use of microbes in which various economic, 
social and environment related processes and products are included. Various microbial 
processes useful for this purpose are carried out. 
 Industrial Microbiology: main features
A. Various productions with the help of fermentation process. Ex. Bread, cheese, wine,   
 raw material for chemicals, enzymes, nutrients, medicines, etc.
B. Use of microbes for garbage management and pollution control.
7. Introduction to Microbiology 
Ø  Applied Microbiology    
Ø  Industrial Microbiology   
Ø  Products   
78
2. Yoghurt Products 
 Yoghurt is a milk product produced with the help of lactobacilli (inoculant). For 
maintaining the protein content, condensed milk powder is mixed with milk to be fermented 
for industrial production of yoghurt. Milk is boiled and once it cools to warm temperature, 
bacterial strains of Streptococcus thermophilus and Lactobacillus delbrueckii are added to it 
in 1:1 proportion. Lactic acid is formed due to Streptococcus that makes the proteins to gel out 
that gives dense consistency to the yoghurt. 
 Acetaldehyde like compounds are formed due to lactobacilli 
that gives characteristic taste to the yoghurt. Now a day, various 
fruit juices are mixed with yoghurt to impart different flavours. Ex. 
Strawberry yoghurt, banana yoghurt, etc. Shelf life of yoghurt and 
its probiotic properties can be improved by pasteurization.
3. Butter
 Two types of butter like sweet cream and cultured are produced 
on large scale. Microbes are used for production of cultured variety. 
4. Cheese production
 Cheese is produced on large scale from the abundantly available 
cow milk all over the world. First, chemical and microbiological 
tests of milk are performed. Some colours and microbes like 
Lactobacillus lactis, Lactobacillus cremoris, and Streptococcus 
thermophilus are mixed with milk. It imparts sourness to the milk. 
After this, to impart the dense texture, whey (water in yoghurt) needs 
to be removed. 
 An enzyme, rennet obtained from alimentary canal of cattle 
was being traditionally used earlier. However, an enzyme protease 
obtained from fungi is used at present to produce vegetarian cheese. 
 The whey is separated from yoghurt (which has some other 
uses). Then, process of production of cheese is started through steps 
Let’s think 
Do you know?
1.  Which different types of cheese are used in western food like  
     pizza, burger, sandwich, etc?
2. What is difference between those types of cheese?
 During industrial production of milk products, strict cleanliness and sterilization 
is essential as bacteria can be attacked by viruses. Hence, virus-resistant varieties of 
bacteria are developed. Recently, use of mutant varieties of bacteria has been increased. 
Artificially, some strains are developed that will help to avoid unnecessary steps / 
materials. 
 Freshly prepared cheese is always soft e.g. cottage cheese, cream cheese, mozzarella 
cheese. On storing for 3 to 12 months, semi-hard cheddar cheese is formed whereas after 
ripening for 12 – 18 months, very hard cheese called parmesan cheese is formed.
7.1 Cheese and Butter
like cutting the solid yoghurt into pieces, washing, rubbing, salting, and mixing of essential 
microbes, pigments and flavours. Then, cheese is pressed and cut in to pieces and stored for 
ripening. 
79
Can you tell?
7.2 Probiotics 
7.3  Vinegar
Probiotics
 These are also milk products, but contain active bacteria e.g. Lactobacillus, 
Acidophilus, Lactobacillus casei, Bifidobacterium bifidum, etc. These microbes maintain 
the balance of intestinal microorganisms i.e. increase the population of microbes helping 
the digestion and decrease the population of harmful microbes (ex. Clostridium). Probiotic 
products are available in various forms like yoghurt, kefir, sauerkraut (pickle of cabbage), 
dark chocolate, miso soup, pickles, oils, corn syrup, artificial sweeteners, microalgae (Sea 
food like Spirulina, Chlorella, Blue green algae,  etc.).
 What for probiotic food is famous?
 Bread
 Different types of breads are produced from flour of cereals. Dough is formed by 
mixing of baker’s yeast – Saccharomyces cerevisiae, water, salt and other necessary 
materials with flour. Due to fermentation of carbohydrates by yeast, sugar is converted in 
to carbon dioxide (CO
2
) and ethanol. Dough rises up due to CO
2 
and the bread becomes 
spongy. 
 Compressed yeast is used in commercial bakery industry. It is available in dry, 
granular form for domestic use. Yeast produced for commercial use contains various 
useful contents like carbohydrates, fats, proteins, various vitamins, and minerals. Due to 
this, bread and other products produced with the help of yeast become nutritive. Ingredients 
like vinegar, soya sauce and monosodium glutamate (ajinomoto) that are used in presently 
popular chinese food are produced by microbial fermentation.
 Why the probiotics have developed much importance in 
recent days? These products form the colonies of useful 
microbes in alimentary canal and control other microbes and 
their metabolic activities, improve resistance and lower the 
ill-effects of harmful substances formed during metabolic 
activities. Useful microbes become inactive due to antibiotics; 
probiotics make them active again. 
 Nowadays, probiotics are used for treatment of diarrhoea 
and treatment of poultry also.
Use your brain power
In the earlier class, you had prepared the solution of 
dry yeast for observation of yeast. Which substance is 
prepared by its use on commercial basis?
Vinegar Production 
 Vinegar is used in each country of the world to impart sour taste to 
food materials and for preservation of pickles, sauce, ketch-up, chutneys, 
etc. Chemically, vinegar is 4% acetic acid (CH
3
COOH).
 Ethanol, an alcohol is obtained by fermentation of carbon 
compounds like fruit juices, maple syrup, sugar molasses, starch of the 
roots; with the help of yeast Saccharomyces cerevisiae.
Page 4


77
1. Which different microbes are useful to us?
2. Which different products can be produced with the help of  
 microbes?
Applied Microbiology
 Branch of biology in which study of the enzymes related to some prokaryotes and 
eukaryotic microbes, proteins, applied genetics, molecular biology, etc. is performed; is 
called as applied microbiology. This study is used for the society and various products like 
food and medicines are produced on large scale with the help of microorganisms.
We use the fermentation process while conversion of milk into 
yoghurt. Which microbes are useful for this process?
Products
A. Dairy Products
 Since ancient days, milk is converted into various products for its preservation purpose. 
Ex. Cheese, butter, cream, kefir, yoghurt, etc. Water content and acidity of the milk changes 
during formation of these products and texture, taste and flavour is improved.
 These processes are performed on large scale with more skill. For production of most 
of the milk products, bacteria in milk itself are used; only cheese is produced with the help 
of fungi. Basic process for production of yoghurt, cheese and cream is same. Milk is 
pasteurized at the beginning to destroy unwanted microbes. It is then fermented with the 
help of lactobacilli. In this process, lactose sugar of the milk is converted into lactic acid 
and milk proteins are coagulated with the help of lactic acid. Besides, compounds with 
taste and flavour are also formed. Ex. Diacetyl has the flavour of butter.
Can you recall?
Can you recall?
Industrial microbiology 
 This science is related to commercial use of microbes in which various economic, 
social and environment related processes and products are included. Various microbial 
processes useful for this purpose are carried out. 
 Industrial Microbiology: main features
A. Various productions with the help of fermentation process. Ex. Bread, cheese, wine,   
 raw material for chemicals, enzymes, nutrients, medicines, etc.
B. Use of microbes for garbage management and pollution control.
7. Introduction to Microbiology 
Ø  Applied Microbiology    
Ø  Industrial Microbiology   
Ø  Products   
78
2. Yoghurt Products 
 Yoghurt is a milk product produced with the help of lactobacilli (inoculant). For 
maintaining the protein content, condensed milk powder is mixed with milk to be fermented 
for industrial production of yoghurt. Milk is boiled and once it cools to warm temperature, 
bacterial strains of Streptococcus thermophilus and Lactobacillus delbrueckii are added to it 
in 1:1 proportion. Lactic acid is formed due to Streptococcus that makes the proteins to gel out 
that gives dense consistency to the yoghurt. 
 Acetaldehyde like compounds are formed due to lactobacilli 
that gives characteristic taste to the yoghurt. Now a day, various 
fruit juices are mixed with yoghurt to impart different flavours. Ex. 
Strawberry yoghurt, banana yoghurt, etc. Shelf life of yoghurt and 
its probiotic properties can be improved by pasteurization.
3. Butter
 Two types of butter like sweet cream and cultured are produced 
on large scale. Microbes are used for production of cultured variety. 
4. Cheese production
 Cheese is produced on large scale from the abundantly available 
cow milk all over the world. First, chemical and microbiological 
tests of milk are performed. Some colours and microbes like 
Lactobacillus lactis, Lactobacillus cremoris, and Streptococcus 
thermophilus are mixed with milk. It imparts sourness to the milk. 
After this, to impart the dense texture, whey (water in yoghurt) needs 
to be removed. 
 An enzyme, rennet obtained from alimentary canal of cattle 
was being traditionally used earlier. However, an enzyme protease 
obtained from fungi is used at present to produce vegetarian cheese. 
 The whey is separated from yoghurt (which has some other 
uses). Then, process of production of cheese is started through steps 
Let’s think 
Do you know?
1.  Which different types of cheese are used in western food like  
     pizza, burger, sandwich, etc?
2. What is difference between those types of cheese?
 During industrial production of milk products, strict cleanliness and sterilization 
is essential as bacteria can be attacked by viruses. Hence, virus-resistant varieties of 
bacteria are developed. Recently, use of mutant varieties of bacteria has been increased. 
Artificially, some strains are developed that will help to avoid unnecessary steps / 
materials. 
 Freshly prepared cheese is always soft e.g. cottage cheese, cream cheese, mozzarella 
cheese. On storing for 3 to 12 months, semi-hard cheddar cheese is formed whereas after 
ripening for 12 – 18 months, very hard cheese called parmesan cheese is formed.
7.1 Cheese and Butter
like cutting the solid yoghurt into pieces, washing, rubbing, salting, and mixing of essential 
microbes, pigments and flavours. Then, cheese is pressed and cut in to pieces and stored for 
ripening. 
79
Can you tell?
7.2 Probiotics 
7.3  Vinegar
Probiotics
 These are also milk products, but contain active bacteria e.g. Lactobacillus, 
Acidophilus, Lactobacillus casei, Bifidobacterium bifidum, etc. These microbes maintain 
the balance of intestinal microorganisms i.e. increase the population of microbes helping 
the digestion and decrease the population of harmful microbes (ex. Clostridium). Probiotic 
products are available in various forms like yoghurt, kefir, sauerkraut (pickle of cabbage), 
dark chocolate, miso soup, pickles, oils, corn syrup, artificial sweeteners, microalgae (Sea 
food like Spirulina, Chlorella, Blue green algae,  etc.).
 What for probiotic food is famous?
 Bread
 Different types of breads are produced from flour of cereals. Dough is formed by 
mixing of baker’s yeast – Saccharomyces cerevisiae, water, salt and other necessary 
materials with flour. Due to fermentation of carbohydrates by yeast, sugar is converted in 
to carbon dioxide (CO
2
) and ethanol. Dough rises up due to CO
2 
and the bread becomes 
spongy. 
 Compressed yeast is used in commercial bakery industry. It is available in dry, 
granular form for domestic use. Yeast produced for commercial use contains various 
useful contents like carbohydrates, fats, proteins, various vitamins, and minerals. Due to 
this, bread and other products produced with the help of yeast become nutritive. Ingredients 
like vinegar, soya sauce and monosodium glutamate (ajinomoto) that are used in presently 
popular chinese food are produced by microbial fermentation.
 Why the probiotics have developed much importance in 
recent days? These products form the colonies of useful 
microbes in alimentary canal and control other microbes and 
their metabolic activities, improve resistance and lower the 
ill-effects of harmful substances formed during metabolic 
activities. Useful microbes become inactive due to antibiotics; 
probiotics make them active again. 
 Nowadays, probiotics are used for treatment of diarrhoea 
and treatment of poultry also.
Use your brain power
In the earlier class, you had prepared the solution of 
dry yeast for observation of yeast. Which substance is 
prepared by its use on commercial basis?
Vinegar Production 
 Vinegar is used in each country of the world to impart sour taste to 
food materials and for preservation of pickles, sauce, ketch-up, chutneys, 
etc. Chemically, vinegar is 4% acetic acid (CH
3
COOH).
 Ethanol, an alcohol is obtained by fermentation of carbon 
compounds like fruit juices, maple syrup, sugar molasses, starch of the 
roots; with the help of yeast Saccharomyces cerevisiae.
80
Can you tell?
Sr. 
No.
Fruit Microbe used Role of microbe Name of 
beverage
1 Caffea arabica Lactobacillus brevis Separating seeds from 
fruit
Coffee
2 Theobroma 
cacao
Candida, Hansenula, 
Pichia,Saccharomyces.
Separating seeds from 
fruit
Cocoa
3 Grapes Saccharomyces cerevisiae Fermentation of juice Wine
4 Apple Saccharomyces cerevisiae Fermentation of juice Cider
Saccharomyces cerevisiae
 Mixture of bacterial strains like Acetobacter and Glucanobacter 
is mixed with ethanol for its microbial degradation. Acetic acid 
and other by-products are obtained through it. Acetic acid is 
separated from mixture by rarefaction. Acetic acid is bleached with 
the help of potassium ferrocynide. Then, it is pasteurized. Finally, 
very small quantity of SO
2
 gas is mixed to produce vinegar.
 Soya sauce is produced by fermentation of the mixture of flour 
of wheat or rice and soyabean with the help of the fungus Aspergillus 
oryzae.
Production of beverages
1. Which functions are performed by enzymes secreted in 
     human  digestive system?
2. Give names of some such enzymes.
Microbial Enzymes 
Nowadays, instead of chemical catalysts, microbial enzymes are used 
in chemical industry. These enzymes are active at low temperature, pH and 
pressure; due to which energy is saved and erosion-proof instruments are also 
not necessary. Enzymes carry out specific processes; hence unnecessary by-
products are not formed due to which expenses on purification are minimised.
In case of microbial enzymatic reactions, elimination and decomposition 
of waste material is avoided and enzymes can be reused. Hence, such 
enzymes are eco-friendly. Some examples of microbial enzymes are oxido-
reductases, transferases, hydrolases, lyases, isomerases, ligases, etc.
Process of dirt / muck removal occurs at low temperature too due to mixing of 
enzymes with detergents. Glucose and fructose syrup can be obtained from corn flour 
by action of enzymes obtained from bacilli and streptomyces. Microbial enzymes 
are used in various industries like cheese, plant extracts, textile, leather, paper, etc.
7.4 Aspergillus oryzae 
Fruit and seeds of coffee
Cocoa seeds 
7.5 Some ingredients of beverages production
Page 5


77
1. Which different microbes are useful to us?
2. Which different products can be produced with the help of  
 microbes?
Applied Microbiology
 Branch of biology in which study of the enzymes related to some prokaryotes and 
eukaryotic microbes, proteins, applied genetics, molecular biology, etc. is performed; is 
called as applied microbiology. This study is used for the society and various products like 
food and medicines are produced on large scale with the help of microorganisms.
We use the fermentation process while conversion of milk into 
yoghurt. Which microbes are useful for this process?
Products
A. Dairy Products
 Since ancient days, milk is converted into various products for its preservation purpose. 
Ex. Cheese, butter, cream, kefir, yoghurt, etc. Water content and acidity of the milk changes 
during formation of these products and texture, taste and flavour is improved.
 These processes are performed on large scale with more skill. For production of most 
of the milk products, bacteria in milk itself are used; only cheese is produced with the help 
of fungi. Basic process for production of yoghurt, cheese and cream is same. Milk is 
pasteurized at the beginning to destroy unwanted microbes. It is then fermented with the 
help of lactobacilli. In this process, lactose sugar of the milk is converted into lactic acid 
and milk proteins are coagulated with the help of lactic acid. Besides, compounds with 
taste and flavour are also formed. Ex. Diacetyl has the flavour of butter.
Can you recall?
Can you recall?
Industrial microbiology 
 This science is related to commercial use of microbes in which various economic, 
social and environment related processes and products are included. Various microbial 
processes useful for this purpose are carried out. 
 Industrial Microbiology: main features
A. Various productions with the help of fermentation process. Ex. Bread, cheese, wine,   
 raw material for chemicals, enzymes, nutrients, medicines, etc.
B. Use of microbes for garbage management and pollution control.
7. Introduction to Microbiology 
Ø  Applied Microbiology    
Ø  Industrial Microbiology   
Ø  Products   
78
2. Yoghurt Products 
 Yoghurt is a milk product produced with the help of lactobacilli (inoculant). For 
maintaining the protein content, condensed milk powder is mixed with milk to be fermented 
for industrial production of yoghurt. Milk is boiled and once it cools to warm temperature, 
bacterial strains of Streptococcus thermophilus and Lactobacillus delbrueckii are added to it 
in 1:1 proportion. Lactic acid is formed due to Streptococcus that makes the proteins to gel out 
that gives dense consistency to the yoghurt. 
 Acetaldehyde like compounds are formed due to lactobacilli 
that gives characteristic taste to the yoghurt. Now a day, various 
fruit juices are mixed with yoghurt to impart different flavours. Ex. 
Strawberry yoghurt, banana yoghurt, etc. Shelf life of yoghurt and 
its probiotic properties can be improved by pasteurization.
3. Butter
 Two types of butter like sweet cream and cultured are produced 
on large scale. Microbes are used for production of cultured variety. 
4. Cheese production
 Cheese is produced on large scale from the abundantly available 
cow milk all over the world. First, chemical and microbiological 
tests of milk are performed. Some colours and microbes like 
Lactobacillus lactis, Lactobacillus cremoris, and Streptococcus 
thermophilus are mixed with milk. It imparts sourness to the milk. 
After this, to impart the dense texture, whey (water in yoghurt) needs 
to be removed. 
 An enzyme, rennet obtained from alimentary canal of cattle 
was being traditionally used earlier. However, an enzyme protease 
obtained from fungi is used at present to produce vegetarian cheese. 
 The whey is separated from yoghurt (which has some other 
uses). Then, process of production of cheese is started through steps 
Let’s think 
Do you know?
1.  Which different types of cheese are used in western food like  
     pizza, burger, sandwich, etc?
2. What is difference between those types of cheese?
 During industrial production of milk products, strict cleanliness and sterilization 
is essential as bacteria can be attacked by viruses. Hence, virus-resistant varieties of 
bacteria are developed. Recently, use of mutant varieties of bacteria has been increased. 
Artificially, some strains are developed that will help to avoid unnecessary steps / 
materials. 
 Freshly prepared cheese is always soft e.g. cottage cheese, cream cheese, mozzarella 
cheese. On storing for 3 to 12 months, semi-hard cheddar cheese is formed whereas after 
ripening for 12 – 18 months, very hard cheese called parmesan cheese is formed.
7.1 Cheese and Butter
like cutting the solid yoghurt into pieces, washing, rubbing, salting, and mixing of essential 
microbes, pigments and flavours. Then, cheese is pressed and cut in to pieces and stored for 
ripening. 
79
Can you tell?
7.2 Probiotics 
7.3  Vinegar
Probiotics
 These are also milk products, but contain active bacteria e.g. Lactobacillus, 
Acidophilus, Lactobacillus casei, Bifidobacterium bifidum, etc. These microbes maintain 
the balance of intestinal microorganisms i.e. increase the population of microbes helping 
the digestion and decrease the population of harmful microbes (ex. Clostridium). Probiotic 
products are available in various forms like yoghurt, kefir, sauerkraut (pickle of cabbage), 
dark chocolate, miso soup, pickles, oils, corn syrup, artificial sweeteners, microalgae (Sea 
food like Spirulina, Chlorella, Blue green algae,  etc.).
 What for probiotic food is famous?
 Bread
 Different types of breads are produced from flour of cereals. Dough is formed by 
mixing of baker’s yeast – Saccharomyces cerevisiae, water, salt and other necessary 
materials with flour. Due to fermentation of carbohydrates by yeast, sugar is converted in 
to carbon dioxide (CO
2
) and ethanol. Dough rises up due to CO
2 
and the bread becomes 
spongy. 
 Compressed yeast is used in commercial bakery industry. It is available in dry, 
granular form for domestic use. Yeast produced for commercial use contains various 
useful contents like carbohydrates, fats, proteins, various vitamins, and minerals. Due to 
this, bread and other products produced with the help of yeast become nutritive. Ingredients 
like vinegar, soya sauce and monosodium glutamate (ajinomoto) that are used in presently 
popular chinese food are produced by microbial fermentation.
 Why the probiotics have developed much importance in 
recent days? These products form the colonies of useful 
microbes in alimentary canal and control other microbes and 
their metabolic activities, improve resistance and lower the 
ill-effects of harmful substances formed during metabolic 
activities. Useful microbes become inactive due to antibiotics; 
probiotics make them active again. 
 Nowadays, probiotics are used for treatment of diarrhoea 
and treatment of poultry also.
Use your brain power
In the earlier class, you had prepared the solution of 
dry yeast for observation of yeast. Which substance is 
prepared by its use on commercial basis?
Vinegar Production 
 Vinegar is used in each country of the world to impart sour taste to 
food materials and for preservation of pickles, sauce, ketch-up, chutneys, 
etc. Chemically, vinegar is 4% acetic acid (CH
3
COOH).
 Ethanol, an alcohol is obtained by fermentation of carbon 
compounds like fruit juices, maple syrup, sugar molasses, starch of the 
roots; with the help of yeast Saccharomyces cerevisiae.
80
Can you tell?
Sr. 
No.
Fruit Microbe used Role of microbe Name of 
beverage
1 Caffea arabica Lactobacillus brevis Separating seeds from 
fruit
Coffee
2 Theobroma 
cacao
Candida, Hansenula, 
Pichia,Saccharomyces.
Separating seeds from 
fruit
Cocoa
3 Grapes Saccharomyces cerevisiae Fermentation of juice Wine
4 Apple Saccharomyces cerevisiae Fermentation of juice Cider
Saccharomyces cerevisiae
 Mixture of bacterial strains like Acetobacter and Glucanobacter 
is mixed with ethanol for its microbial degradation. Acetic acid 
and other by-products are obtained through it. Acetic acid is 
separated from mixture by rarefaction. Acetic acid is bleached with 
the help of potassium ferrocynide. Then, it is pasteurized. Finally, 
very small quantity of SO
2
 gas is mixed to produce vinegar.
 Soya sauce is produced by fermentation of the mixture of flour 
of wheat or rice and soyabean with the help of the fungus Aspergillus 
oryzae.
Production of beverages
1. Which functions are performed by enzymes secreted in 
     human  digestive system?
2. Give names of some such enzymes.
Microbial Enzymes 
Nowadays, instead of chemical catalysts, microbial enzymes are used 
in chemical industry. These enzymes are active at low temperature, pH and 
pressure; due to which energy is saved and erosion-proof instruments are also 
not necessary. Enzymes carry out specific processes; hence unnecessary by-
products are not formed due to which expenses on purification are minimised.
In case of microbial enzymatic reactions, elimination and decomposition 
of waste material is avoided and enzymes can be reused. Hence, such 
enzymes are eco-friendly. Some examples of microbial enzymes are oxido-
reductases, transferases, hydrolases, lyases, isomerases, ligases, etc.
Process of dirt / muck removal occurs at low temperature too due to mixing of 
enzymes with detergents. Glucose and fructose syrup can be obtained from corn flour 
by action of enzymes obtained from bacilli and streptomyces. Microbial enzymes 
are used in various industries like cheese, plant extracts, textile, leather, paper, etc.
7.4 Aspergillus oryzae 
Fruit and seeds of coffee
Cocoa seeds 
7.5 Some ingredients of beverages production
81
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7.6  Aspergilus niger
Source Microbe Amino acid Use
Sugar and beet 
molasses, ammonia 
salt
Brevibacterium, 
Corynobacterium
L-glutamic acid Production of monosodium 
glutamate (Ajinomoto)
Sugar molasses, 
salt
Aspergillus niger Citric acid Drinks, toffees, chocolate 
production
Glucose, corn steep 
liquor
Aspergillus niger Gluconic acid Production of minerals used 
as supplement for calcium 
and iron
Molasses, corn 
steep liquor
Lactobacillus 
delbrueckii
Lactic acid Source of nitrogen, 
production of vitamins.
Molasses, corn 
steep liquor
Aspergillus 
itaconius
Itaconic acid Paper, textile, plastic 
industry, gum production
Substances obtained by microbial processing Roles
Citirc, Malic and Lactic acid To impart acidity
Glutamic acid, Lysine, Tryptophan Protein binding
Nycin and natamycin Microbial restrictor
Ascorbic acid (Vit. C), B
12
, B
2
Antioxidants, vitamins. 
Beta carotene, lycopenes, xanthenes, lutein Edible colours
Polysaccharides, glycolipids Emulsifiers
Vanillin, Ethyl butyrate (fruit flavour), peppermint 
flavour, essence of various fruits and flowers
Essence
Xylitol, aspartame Artificial sweetener (low calorie) 
Substances obtained by microbial processing and their roles
Use your brain power
Food materials like cold drinks, ice creams, cakes, juices 
are available in various colours and flavours. Whether these 
colours and flavours are really derived from fruits?
 Read the ingredients and their proportion printed on bottles of cold 
drinks and juices and wrappers of ice creams. Find out the natural and 
artificial ingredients. Wheat or rice flour is inoculated with Aspergillus.  
 What is the xanthan gum that imparts thickness to 
your favourite ice creams, puddings, chocolates, milk 
shakes, chocolate drinks, instant soups, etc.? This gum 
is obtained by fermentation of starch and molasses with 
the help of Xanthomonas species. It is variously useful 
due to properties like solubility in hot and cold water, 
high density, etc. It is used for production of pigments, 
fertilizers, weedicides, textile pigments, tooth pastes, 
high quality paper, etc.
Organic acids used in various commercial products and microbes useful for the same
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