MHT CET Pyq Chapterwise Pdf

What is Fermentation? Definition, History, Types, Advantages : 

Definition of Fermentation : 

• Fermentation is a process in which complex substances are converted into simple substances with the help of microorganisms.

• Fermentation is a chemical reaction in which sugars are broken down into smaller molecules by bacteria and yeast.

What is Fermentation?

• Fermentation is a biochemical process in which complex organic substances are converted into simple substances with the help of bacteria yeasts and other microorganisms known as fermentation.

• The word fermentation is derived from the Latin verb serve, which means to boil. 

• The study of fermentation is known as Zymology.

• In 1857 French chemist and microbiologist Louis Pasteur firstly used the term fermentation, he discovered that microorganisms, such as bacteria and fungus (yeasts) can cause fermentation.

• Louis Pasteur was the first to demonstrate practically that fermented beverages are the result of the action of living yeast which converts glucose into ethanol.

• Louis Pasteur is known as the father of fermentation. 

• The fermentation process is carried out in a special type of vessel known as a Fermenter or Bioreactor.

• The bioreactor is defined as a vessel that carries out a biological reaction and it provides a controlled environment such as temperature, pH, substrate, salts, vitamins, oxygen, etc for the growth of microorganisms and product formation. 

• There are different types of bioreactors. The major types are Continuous Stirred Tank Bioreactors, Bubble Column Bioreactor, Airlift Bioreactors, Fluidized Bed Bioreactors, Packed Bed Bioreactors, etc.

• There are different types of fermentation based on media, type of fermenter, and type of end product. 

• The fermentation process is used for the production of alcoholic beverages like beer, wine, ethanol, bread, yogurt, vinegar, and kombucha and acetic acid, citric acid, gluconic acid, antibiotics, vitamins (Vitamins B12 &  B2), enzymes, etc.

History of Fermentation  : 

• Humans have had a long history of using microbial fermentation to make food and drinks for thousands of years, but people have not fully understood the fermentation process before. 
• In 1680 Leeuwenhoek observed intact yeast cells for the first time.
• In 1854, French chemist Pasteur discovered that the fermentation of yeast is the real cause of alcohol fermentation.
• In 1897, German chemist Bischner discovered that the essence of carbohydrate fermentation is the various enzymes contained in yeast.
• After people began to gradually understand the essence of fermentation, the history of fermented food entered the period of pure culture technology. 
• Pure culture technology marked the transition from natural fermentation to pure culture and artificially controlled fermentation. 
• It was the first turning point in the development of the fermentation industry. It is also the beginning of modern fermentation technology.

The Heart of Fermentation Bioreactor / Fermenter  : 

• The fermentation process is carried out in a special type of vessel known as a Fermenter or Bioreactor.
• The bioreactor is defined as a vessel that carries out a biological reaction and it provides a controlled environment such as temperature, pH, substrate, salts, vitamins, oxygen, etc for the growth of microorganisms and product formation.
• There are different types of bioreactors. The major types are Continuous Stirred Tank Bioreactors, Bubble Column Bioreactor, Airlift Bioreactors, Fluidized Bed Bioreactors, Packed Bed Bioreactors, etc.
• A fermentation tank refers to a device used for microbial fermentation in industry. Fermentation tanks are widely used in beverage, chemical, food, dairy, condiment, brewing, pharmaceutical, and other industries to play a fermenting role. 
• The components of the fermentation tank include: the tank body is mainly used for cultivating and fermenting various bacteria, with good sealing (to prevent the bacteria from being contaminated), 
• There is a stirring slurry in the tank, which is used for continuous stirring during the fermentation process; 
• There is aeration at the bottom 
• The Sparger is used to pass in the air or oxygen needed for the growth of the bacteria. 
• There are control sensors on the top plate of the tank. The most commonly used are pH electrodes and DO electrodes to monitor the changes in the pH and DO of the fermentation broth during the fermentation process.
• The controller is used to display and control the fermentation conditions. 
• According to the equipment of the fermentation tank, it is divided into mechanical stirring and ventilation fermentation tank and non-mechanical stirring and ventilation fermentation tank; according to the growth and metabolism of microorganisms, it is divided into the aerobic fermentation tank and anaerobic fermentation tank.

Types of Fermentation : 

There are several types of fermentation, based on Media, type of fermenter, and type of end products. These fermentation types will be explained below. Check out!

1. Based on Media / Substrates, there are two types of fermentation solid state fermentation and Submerged fermentation. 
2. Based on the type of fermenter, there are two types of fermentation Batch fermentation and continuous fermentation.
3. Based on the end product, fermentation is of two types Aerobic fermentation and Anaerobic fermentation (Alcoholic/ethanol fermentation & Lactic acid fermentation).

Based on Media or Substrates: 

1. Solid State Fermentation: 

1. Solid state fermentation (SSF) is a biochemical process that involves the cultivation of microorganisms on a solid substrate with low moisture content.
2. In the Solid state, fermentation biomolecules are manufactured and are used in the food industry, pharmaceutical industry, cosmetic products, fuel, and textile industries, etc.
3. The most commonly used solid substrates in SSF are plant and animal materials, cereal grains such as Corn, rice, wheat, and barley), legume seeds, straws, sawdust or wood, etc.
4. SSF fermented products mainly involve in bakery products such as bread or for the maturing of cheese. 
5. One of the major advantage of SSF it gives higher yields and productivity, lowers production cost, and lower protein breakdown also.

2. Submerged Fermentation (SMF) : 

1. Submerged fermentation (SMF) is an anaerobic process involved in the inoculation of the microbial culture into the liquid medium for the production of biomolecules known as Submerged fermentation. 
2. In the submerged fermentation process, the substrate used for fermentation is always in a liquid state which contains all the nutrients required for the growth and development of microorganisms for the production of desired products.
3. There are four different types of submerged fermentation batch fermentation, continuous fermentation, fed-batch fermentation, and perfusion batch culture fermentation.
4. Following are examples of submerged fermentation production of citric acid, biological detergent synthesis, starch hydrolysis, cheese making, and wine production.

Based on the type of fermenter or Bioreactor:

1. Batch Fermentation: 

1. In batch processes loading of raw materials and seed material into the apparatus is carried out at a time.
2. Then the process goes on in the apparatus for a certain time, and after its completion, the resulting fermentation liquid is unloaded from the apparatus.
3. This type of fermentation has very important advantages. 
4. Many valuable products such as antibiotics, extracellular enzymes, polysaccharides, etc are obtained during the industrial cultivation of microorganisms.

2. Continuous Fermentation: 

1. In continuous fermentation, fresh nutrients are constantly fed into the culture and at the same time, the same volume of cell suspension is removed from it. 
2. Continuous fermentation can be carried out in a reactor with a constant nutrient feed rate.
3. Continuous fermentation is very important for the selection and improvement of industrial fermentation conditions, as well as for studying the effect of a reduced content of a certain medium component on cell growth. 
4. In industry, continuous fermentation is not widely used, but these processes are used in aerobic or anaerobic wastewater treatment, as well as in brewing and the production of human insulin using recombinant yeast strains. 
5. Compared to batch fermentation, continuous fermentation has several disadvantages: (a) The economic advantages of a continuous process only become apparent after 500–1000 hours of fermentation, but the costs of maintaining a sterile reactor for such a long time can be quite significant; (b) control and maintenance of a homogeneous composition of the nutrient medium for a long period also require additional measures; (c) not all recombinant strains used in industry retain their genetically programmed properties for a long time. 

Based on End Product fermentation types : 

1. Aerobic Fermentation : 

Aerobic fermentation consists of the assimilation of organic matter by microorganisms in the presence of oxygen and nutrients. Aerobic fermentation generally occurs within living organisms. Aerobic fermentation takes place in the mitochondria and the cytoplasm of the cell. In Aerobic fermentation Glucose completely breaks down into oxygen and carbon dioxide.

2. Anaerobic Fermentation :  

Anaerobic fermentation is a method that cells use to extract energy from carbohydrates in absence of oxygen. The process of anaerobic fermentation starts with glycolysis in that glucose and other sugars are oxidized to produce adenosine triphosphate (ATP) molecules that create an energy source for the cell. There are two main types of anaerobic fermentation: ethanol fermentation and lactic acid fermentation. Both restore NAD + to allow a cell to continue to generate ATP through glycolysis.

Alcoholic fermentation : 

1. Alcoholic fermentation is defined as it is a biochemical process in which sugar molecules are converted into alcohol and carbon dioxide with the help of yeast.
2. Alcoholic fermentation is also known as ethanol fermentation.
3. The main function of ethanol fermentation is to produce ATP under anaerobic conditions.
4. This process is used for the production of alcoholic beverages, such as wine and beer, and it only happens because of the yeasts that carry out the fermentation process.
5. The alcoholic fermentation process starts with the breakdown of sugar molecules to form pyruvate by the yeasts, which is commonly known as glycolysis.
6. Glycolysis of a glucose molecule produces two molecules of pyruvate. Then these two molecules of pyruvate are reduced into two acetaldehyde, and this acetaldehyde is converted into two ethanol molecules and two molecules of carbon dioxide. 
7. During alcoholic fermentation, the final electron acceptor is NAD+ and it is reduced to form NADH. and this exchange of electrons results in the formation of cellular energy (ATP).

Lactic acid Fermentation

1. Lactic acid fermentation is defined as it is a biochemical process in which sugar molecules are converted into lactic acid with the release of ATP Molecules by various Bacteria Lactobacillus. 
2. Lactobacilli are the bacteria responsible for carrying out the lactic fermentation process. These bacteria are widely used for the fermentation of milk in the production of yogurt, fermented milk, and other derivatives.
3. Lactic Acid fermentation is also known as Lacto fermentation / Lactate Fermentation.
4. This process is used for the production of lactic acid itself and NAD+
5. The lactic acid fermentation process starts with the breakdown of sugar molecules to form pyruvate by the Lactobacillus, which is commonly known as glycolysis.
6. Glycolysis of a glucose molecule produces two molecules of pyruvate. Then these two molecules of pyruvate are converted into two molecules of Lactate and ATP.
7. During Lactate fermentation, the final electron acceptor is NAD+ and it is reduced to form NADH. and this exchange of electrons results in the formation of cellular energy (ATP).

The general process of Fermentation: 

Fermentation occurs in a bioreactor. A conventional bioreactor is a closed cylinder in which the medium is mechanically mixed along with microorganisms. Air, sometimes saturated with oxygen, is pumped through it. The temperature is controlled by water or steam passing through the tubes of the heat exchanger. The design of the bioreactor should allow you to control the growth conditions: constant temperature, pH (acidity or alkalinity), and the concentration of oxygen dissolved in the medium.

• Preparation of culture medium: The nutrient medium serves as a source of organic carbon, the main building block of life. Microorganisms absorb a wide range of organic compounds - from methane (CH4), methanol (CH3 OH), and carbon dioxide (CO2) to natural biopolymers. In addition to carbon, cells need nitrogen, phosphorus, and other elements (K, Mg, Zn, Fe, Cu, Mo, Mn, etc.). An important element in the preparation of nutrient media is sterilization to destroy all foreign microorganisms. It is carried out by thermal, radiation, filtration, or chemical methods.

• Obtaining pure strains for introduction into the fermenter: Before starting the fermentation process, it is necessary to obtain a pure, highly productive culture. A pure culture of microorganisms is stored in very small volumes and under conditions that ensure its viability and productivity (usually this is achieved by storage at low temperature). It is necessary to maintain the purity of the culture at all times, preventing its contamination by foreign microorganisms.

• Actual Fermentation: Fermentation is the main stage of the biotechnological process. Fermentation is the whole set of operations from the introduction of microbes into a medium prepared and heated to the required temperature until the completion of the biosynthesis of the target product or cell growth. The whole process takes place in a special installation - a fermenter. At the end of fermentation, a mixture of working microorganisms, a solution of unconsumed nutrients, and biosynthetic products are formed. It is called culture liquid or broth.

• Isolation and purification of the final product: Upon completion of the fermentation, the product that was desired to be obtained is purified from other components of the broth. For this, various technological methods are used: filtration, separation (sedimentation of suspended particles under the action of centrifugal force), chemical precipitation, etc.

Factors Affecting Fermentation Process  : 

Here you can find 5 factors that affect fermentation process

1. Temperature : 

• The temperature has many effects on the fermentation process. 
• It will affect the rate of various enzyme reactions, change the direction of synthesis of bacterial metabolites and affect the metabolic regulation mechanism of microorganisms. 
• In addition to these direct effects, temperature also affects the physical and chemical properties of the fermentation broth, such as the viscosity of the fermentation broth, the solubility and transfer rate of substrate and oxygen in the fermentation broth, the decomposition and absorption rate of certain substrates, etc., which in turn affect the fermentation Kinetic properties and biosynthesis of products.

2. pH : 

The effects of pH on the growth and reproduction of microorganisms and product synthesis are as follows:

• Affect the activity of enzymes. When the pH value inhibits the activity of certain enzymes in the bacteria, it will hinder the metabolism of the bacteria.
• Affect the charge state of the microbial cell membrane, change the permeability of the cell membrane, and affect the absorption of nutrients and the excretion of metabolites by the microorganisms.
• Affect the dissociation of certain components and intermediate metabolites in the culture medium, thereby affecting the utilization of these substances by microorganisms.
• Different pH values ​​often lead to different metabolic processes of the bacteria and change the quality and proportion of metabolites.
• Each type of microorganism has its optimum and tolerable pH range. The optimum pH for most bacteria growth is 6.3~7.5, molds and yeasts are 3~6, ​​and actinomycetes are 7~8. Moreover, the optimum pH values ​​in the microbial growth stage and the product synthesis stage are often different and need to be determined according to the experimental results.

3. Dissolved oxygen concentration : 

• For aerobic fermentation, the dissolved oxygen concentration is one of the most important parameters. 
• When microorganisms are cultivated in deep layers, an appropriate amount of dissolved oxygen is needed to maintain their respiratory metabolism and the synthesis of certain products. 
• Insufficient oxygen will cause abnormal metabolism and reduce yield. 
• The optimum oxygen concentration and critical oxygen concentration for microbial fermentation are different. 
• The former refers to the concentration of dissolved oxygen that has the best concentration range for growth or synthesis, and the latter generally refers to the lowest oxygen concentration allowed for bacterial respiration. 
• To avoid biosynthesis under oxygen-limited conditions, it is necessary to investigate the critical oxygen concentration and the maximum oxygen concentration of each fermentation process and keep it in the range of the maximum oxygen concentration.

Importance of Fermentation  : 

• Fermentation has many functions such as adding new flavors and textures to food.
• Fermented foods improve digestion by degrading nutrients into digestible forms. 
• The importance of fermentation is widely known in the brewing of alcoholic beverages, for example, beer, and wine are produced from the fermentation of yeast and sugar such as grapes, rice, grain, and berries. 
• With the help of fermentation, we can produce ethyl alcohol and which can use as fuel.
• Fermentation processes are widely used at the industrial level to produce commercial products. 
• The fermentation process is used for the production of alcoholic beverages like beer, wine, ethanol, bread, yogurt, vinegar and kombucha and acetic acid, citric acid, gluconic acid, antibiotics, proteases, vitamins (Vitamins B12 & B2), medicines, and other chemicals, etc.
• Various dairy products such as bread, Cultured buttermilk, Chinese, sour cream, kefir, and yogurt are produced with the help of specific organisms, such as Lactobacillus and Streptococcus, etc.
• With the help of fermentation, methane is produced by sewage water treatment with sediments of plants and freshwater.
• Fermentation is also useful for vaccine production.

Frequently Asked Questions on Fermentation: 

1. What does fermentation mean?

Answer: Fermentation is the process of the breakdown of complex organic substances into simple substances with the help of microorganisms. Fermentation usually occurs in living organisms.

2. What is microbial fermentation?

Answer: Microbial fermentation refers to the process of using microorganisms to convert raw materials into products required by humans through specific metabolic pathways under suitable conditions. The level of microbial fermentation production mainly depends on the genetic characteristics and culture conditions of the strain itself. The scope of application of fermentation engineering Pharmaceutical industry, food industry, energy industry, chemical industry, agriculture: genetic modification of plants; biological nitrogen fixation; engineering insecticides, biological pesticides; microbial nutrients.

3. Are fermented foods good?

Answer: The nutrients are conducive to the absorption of yeast after fermentation, and it is also a strong antioxidant, which can protect the liver and has a certain detoxification effect. Selenium, chromium, and other minerals in yeast can resist aging, be anti-tumor, prevent arteriosclerosis, and improve human immunity.

4. What is fermentation in biology?

Answer: Fermentation is an anaerobic process in which energy can be released from glucose even though oxygen is not available. Fermentation occurs in yeast cells, and a form of fermentation takes place in bacteria and in the muscle cells of animals. Fermentation is widely used in the pharmaceutical and food industries.

5. What is the importance of fermentation?

Answer: Fermentation has many functions such as adding new flavors and textures to food, extending the shelf life of foods, making some nutrients more easily absorbed by the body, and providing an environment for probiotics to grow and reproduce.

6. What is fermentation? Describe its importance.

Answer: Fermentation is the process in which microorganisms produce CO2 and simple organic substances such as ethyl alcohol, lactic acid, malic acid, oxalic acid, citric acid, etc., by the incomplete oxidation of glucose or sugar outside the cell. , as a result of which some energy is released.

Importance of Fermentation - The process of fermentation has the following importance-

• With the help of fermentation alcohol, beer, cheese, wine, etc. are produced.
• Many important organic compounds like acetic acid, glutaric acid etc. are produced by this process.
• This technique is used in the bakery and vinegar industry.
• Fermentation technology is used in industries like pharma, medical, food, tobacco, tea, leather etc.
• It is used in the manufacture of paints, soaps, plastics, resins, and ethers.