Fermentation, chemical process by which Molecules such as glucose are broken down anaerobically. More broadly, fermentation is the foaming that occurs during the manufacture of wine and beer, a process at least 10,000 years old. The frothing results from the evolution of carbon dioxide gas, though this was not recognized until the 17th century. French chemist and microbiologist Louis Pasteur in the 19th century used the term fermentation in a narrow sense to describe the changes brought about by yeasts and other Microorganisms growing in the absence of air (anaerobically); he also recognized that ethyl alcohol and carbon dioxide are not the only products of fermentation.
Anaerobic Breakdown Of Molecules
In the 1920s it was discovered that, in the absence of air, extracts of muscle catalyze the formation of lactate from glucose and that the same intermediate compounds formed in the fermentation of grain are produced by muscle. An important generalization thus emerged: that fermentation reactions are not peculiar to the action of yeast but also occur in many other instances of glucose utilization.
Glycolysis, the breakdown of sugar, was originally defined about 1930 as the Metabolism of sugar into lactate. It can be further defined as that form of fermentation, characteristic of cells in general, in which the six-carbon sugar glucose is broken down into two molecules of the three-carbon organic acid, pyruvic acid (the nonionized form of pyruvate), coupled with the transfer of chemical energy to the synthesis of adenosine triphosphate (ATP). The pyruvate may then be oxidized, in the presence of Oxygen, through the tricarboxylic acid cycle, or in the absence of oxygen, be reduced to lactic acid, alcohol, or other products. The sequence from glucose to pyruvate is often called the Embden–Meyerhof pathway, named after two German biochemists who in the late 1920s and ’30s postulated and analyzed experimentally the critical steps in that series of reactions.
The term fermentation now denotes the enzyme-catalyzed, energy-yielding pathway in cells involving the anaerobic breakdown of molecules such as glucose. In most cells the ENZYMES occur in the soluble portion of the cytoplasm. The reactions leading to the formation of ATP and pyruvate thus are common to sugar transformation in muscle, yeasts, some bacteria, and Plants.
Industrial Fermentation
Industrial fermentation processes begin with suitable microorganisms and specified conditions, such as careful adjustment of nutrient concentration. The products are of many types: alcohol, glycerol, and carbon dioxide from yeast fermentation of various sugars; butyl alcohol, acetone, lactic acid, monosodium glutamate, and acetic acid from various bacteria; and citric acid, gluconic acid, and small amounts of antibiotics, vitamin B12, and riboflavin (vitamin B2) from mold fermentation. Ethyl alcohol produced via the fermentation of starch or sugar is an important source of liquid biofuel.
Alcoholic Fermentation
Alcoholic fermentation generally means production of ethanol (CH3CH2OH). Commonly yeasts, particularly Saccharomyces cerevisiae, are used for production of various alcoholic beverages, as well as industrial alcohol. Yeasts are essentially aerobic organisms, but they can also grow as facultative anaerobes.
The energy-yield under anaerobic conditions is much lower and hence the Growth is slower with much lower cell-yield. When grown with aeration, the cell-yield increases dramatically, but alcohol production falls. Thus, oxygen inhibits fermentation. This is known as Pasteur-effect.
Conversion of pyruvic acid to ethanol proceeds in two steps: pyruvic acid to acetaldehyde and acetaldehyde to ethanol. The first step is catalysed by pyruvic acid decarboxylase which requires TPP as coenzyme, and the second step by alcohol dehydrogenase which requires NADH2 as coenzyme.
Lactic Acid Fermentation
Lactic acid fermentations are of two types:
Homo-fermentative and Heterofermentative.
In the first type, lactic acid is produced as the sole product by reduction of pyruvic acid with the help of the enzyme lactic acid dehydrogenase. The reaction regenerates NAD from NADH2 which is reused for oxidation of GAP to DPGA in the glycolytic pathway.
As one molecule of lactic acid is formed from one molecule of pyruvic acid, two molecules of lactic acid are produced from each molecule of glucose, when it is dissimilated through EMP. In heterofermentative type, the products are lactic acid and ethanol or acetic acid and CO2. The heterofermentative lactic acid bacteria dissimilate glucose via PPC. They produce lactic acid from one-half of the glucose molecule, and ethanol or acetic acid and CO2 from the other half.
Homolactic fermentation is the simplest of all fermentations, involving only a single step in which pyruvic acid is reduced to lactic acid. Lactic acid is formed also in muscles by a similar reaction.
ropionic Acid Fermentation: Propionic acid (CH3-CH2-COOH) is produced by several anaerobic bacteria among which are the coryneform Propionibacterium, and Veillonella, Clostridium, Selenomonas etc. Propionibacterium acidipropionici and P. freudenreichii are the main propionic acid fermenters. Propionibacteria possess cytochromes and catalase and can tolerate some amount of oxygen. They are natural inhabitants of rumen of herbivorous cattle.
The propionic acid bacteria dissimilate glucose via EMP and produce pyruvic acid. By a biotin- linked carboxylation reaction pyruvic acid is converted to oxalacetic acid which is then reduced in two steps to succinic acid through reversal of TCA cycle reactions.
Butanol Fermentation
The bacteria carrying out butyric acid-butanol fermentation are all obligately anaerobic spore- forming bacteria belonging to the genus Clostridium. Besides butyric acid and n-butanol, several other products of this fermentation are acetic acid, ethanol, isopropanol and acetone depending on species.
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Fermentation is a metabolic process that converts Carbohydrates into alcohol or acids using enzymes. It is a type of anaerobic Respiration that does not require oxygen. Fermentation is used to produce a variety of products, including alcoholic beverages, bread, cheese, and yogurt.
Alcoholic fermentation is the process by which yeast converts glucose into ethanol and carbon dioxide. This process is used to make beer, wine, and other alcoholic beverages.
Anaerobic fermentation is a type of fermentation that does not require oxygen. This type of fermentation is used to produce lactic acid, which is used in the production of cheese and yogurt.
Lactic acid fermentation is the process by which bacteria convert glucose into lactic acid. This process is used to produce sauerkraut, kimchi, and other fermented vegetables.
Malolactic fermentation is a secondary fermentation that occurs in winemaking. This process converts malic acid into lactic acid, which makes the wine taste smoother.
Acetification is the process by which acetic acid is produced from ethanol. This process is used to make vinegar.
Biogas production is the process of producing biogas from organic matter. Biogas is a mixture of methane and carbon dioxide, and it can be used as a fuel.
Bioethanol production is the process of producing ethanol from Biomass/”>Biomass. Ethanol is a renewable fuel that can be used to power cars.
Biobutanol production is the process of producing butanol from biomass. Butanol is a biofuel that can be used to power cars.
Biohydrogen production is the process of producing hydrogen from biomass. Hydrogen is a clean fuel that can be used to power cars.
Bioplastic production is the process of producing bioplastics from biomass. Bioplastics are plastics that are made from renewable Resources.
Cheesemaking is the process of making cheese from milk. Cheese is made by adding bacteria to milk, which convert the lactose in milk into lactic acid. The lactic acid causes the milk to curdle, and the curds are then pressed into cheese.
Kombucha is a fermented tea drink. Kombucha is made by adding a SCOBY (symbiotic culture of bacteria and yeast) to sweetened black or green tea. The SCOBY ferments the tea, producing a slightly sweet and sour drink.
Kefir is a fermented milk drink. Kefir is made by adding kefir grains to milk. The kefir grains are a colony of bacteria and yeast that ferment the milk, producing a slightly fizzy and slightly sour drink.
Kimchi is a fermented cabbage dish. Kimchi is made by adding cabbage to a mixture of salt, garlic, ginger, and chili peppers. The cabbage is then fermented for several days, producing a sour and spicy dish.
Sauerkraut is a fermented cabbage dish. Sauerkraut is made by adding cabbage to a mixture of salt and water. The cabbage is then fermented for several weeks, producing a sour and salty dish.
Soy sauce is a fermented soy sauce. Soy sauce is made by fermenting soybeans, wheat, and water. The mixture is fermented for several months, producing a salty and flavorful sauce.
Tempeh is a fermented soybean dish. Tempeh is made by fermenting soybeans with a mold called Rhizopus oligosporus. The soybeans are fermented for several days, producing a firm and flavorful dish.
Vinegar is a fermented alcoholic beverage. Vinegar is made by fermenting wine or cider. The alcohol is then converted into acetic acid by bacteria. Vinegar is used as a condiment and as a preservative.
Fermentation is a versatile process that can be used to produce a variety of products. It is a sustainable process that does not require the use of fossil fuels. Fermentation is an important part of our food system, and it has been used for centuries to produce delicious and nutritious foods.
Baking
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What is baking?
Baking is a method of cooking that uses heat to transform ingredients into a consumable product. The most common ingredients used in baking are flour, water, sugar, eggs, and fat. -
What are the different types of baking?
There are many different types of baking, but some of the most common include bread baking, cake baking, and pastry baking. -
What are the different types of ovens?
There are many different types of ovens, but some of the most common include gas ovens, electric ovens, and convection ovens. -
What are the different types of baking pans?
There are many different types of baking pans, but some of the most common include cake pans, Pie pans, and muffin tins. -
What are the different types of baking tools?
There are many different types of baking tools, but some of the most common include measuring cups, measuring spoons, and mixing bowls.
Cooking
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What is cooking?
Cooking is the process of preparing food for consumption with or without the use of heat. Cooking techniques are used to improve the taste, texture, and appearance of food, and to make it safe to eat. -
What are the different types of cooking?
There are many different types of cooking, but some of the most common include baking, frying, grilling, and roasting. -
What are the different types of cooking appliances?
There are many different types of cooking appliances, but some of the most common include ovens, stoves, and microwaves. -
What are the different types of cooking utensils?
There are many different types of cooking utensils, but some of the most common include knives, pots, and pans. -
What are the different types of cooking ingredients?
There are many different types of cooking ingredients, but some of the most common include meat, vegetables, fruits, and grains.
Food safety
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What is food safety?
Food safety is the practice of preventing foodborne illness. Foodborne illness is caused by eating food that is contaminated with harmful bacteria, viruses, or parasites. -
How can I prevent foodborne illness?
There are many ways to prevent foodborne illness, but some of the most important include: -
Washing your hands thoroughly before and after handling food.
- Cooking food to the proper temperature.
- Keeping food at safe temperatures.
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Avoiding cross-contamination.
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What are the symptoms of foodborne illness?
The symptoms of foodborne illness can vary depending on the type of illness, but some common symptoms include: -
Nausea
- Vomiting
- Diarrhea
- Fever
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Abdominal cramps
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What should I do if I think I have foodborne illness?
If you think you have foodborne illness, it is important to see a doctor right away. Foodborne illness can be serious, especially for young children, pregnant Women, and people with weakened immune systems. -
How can I keep my food safe?
There are many ways to keep your food safe, but some of the most important include: -
Washing your hands thoroughly before and after handling food.
- Cooking food to the proper temperature.
- Keeping food at safe temperatures.
- Avoiding cross-contamination.
- Properly storing food.
- Properly disposing of food waste.
Question 1
Which of the following is a type of fermentation?
(A) Alcoholic fermentation
(B) Lactic acid fermentation
(C) Acetic acid fermentation
(D) All of the above
Answer
(D) All of the above
Explanation
Fermentation is a metabolic process that produces energy in the absence of oxygen. There are three main types of fermentation: alcoholic fermentation, lactic acid fermentation, and acetic acid fermentation.
In alcoholic fermentation, glucose is converted to ethanol and carbon dioxide. This type of fermentation is used in the production of beer, wine, and other alcoholic beverages.
In lactic acid fermentation, glucose is converted to lactic acid. This type of fermentation is used in the production of yogurt, cheese, and sauerkraut.
In acetic acid fermentation, ethanol is converted to acetic acid. This type of fermentation is used in the production of vinegar.
Question 2
Which of the following is an example of a microorganism that uses fermentation?
(A) Yeast
(B) Bacteria
(C) Mold
(D) All of the above
Answer
(D) All of the above
Explanation
Yeast, bacteria, and mold are all microorganisms that can use fermentation to produce energy. Yeast is used in the production of beer, wine, and other alcoholic beverages. Bacteria are used in the production of yogurt, cheese, and sauerkraut. Mold is used in the production of vinegar.
Question 3
Which of the following is a product of fermentation?
(A) Ethanol
(B) Lactic acid
(C) Acetic acid
(D) All of the above
Answer
(D) All of the above
Explanation
Ethanol, lactic acid, and acetic acid are all products of fermentation. Ethanol is produced by yeast during alcoholic fermentation. Lactic acid is produced by bacteria during lactic acid fermentation. Acetic acid is produced by bacteria during acetic acid fermentation.
Question 4
Which of the following is a use of fermentation?
(A) Production of alcoholic beverages
(B) Production of Dairy products
(C) Production of vinegar
(D) All of the above
Answer
(D) All of the above
Explanation
Fermentation is used in the production of alcoholic beverages, dairy products, and vinegar. Alcoholic beverages are produced by yeast during alcoholic fermentation. Dairy products are produced by bacteria during lactic acid fermentation. Vinegar is produced by bacteria during acetic acid fermentation.
Question 5
Which of the following is a benefit of fermentation?
(A) It produces energy in the absence of oxygen.
(B) It can be used to produce a variety of products.
(C) It is a natural process.
(D) All of the above
Answer
(D) All of the above
Explanation
Fermentation produces energy in the absence of oxygen. It can be used to produce a variety of products, including alcoholic beverages, dairy products, and vinegar. It is a natural process that has been used for centuries.