What is fermentation (acetic Lactic acid and alcoholic)

Fermentation in Food Processing The decomposition of carbohydrates by microorganisms or enzymes is fermentation. Fermentation of food results in the production of organic acid, alcohol, etc., which not only help in preserving the food but may also produce distinctive new food products. fermentation is used in different ways which require clarification. When chemical change is discussed at the molecular level. In the context of comparative physiology and biochemistry, the term fermentation is correctly employed to describe the breakdown of carbohydrate material under anaerobic conditions.

Fermentation refers to the breakdown of carbohydrates and carbohydrate-like materials under either anaerobic or aerobic conditions. Conversion of lactose to lactic acid by Streptococcus lactic bacteria is favored by anaerobic conditions and is true fermentation; conversion by ethyl alcohol to acetic acid by acetobacter Aceti bacteria is favored by aerobic conditions and more correctly termed oxidation rather than fermentation.

What is fermentation in food?

Fermentation in Food Processing or the term fermented food is used to describe a special class of food products characterized by various kinds of carbohydrate breakdown but seldom is a carbohydrate-only constituted acted upon. Most fermented foods contain a complex mixture of carbohydrates, proteins, fats, and so on, undergoing modification simultaneously, or in some sequence, under the action of a variety of microorganisms and enzymes.

Fermentation in Food Processing Fermentation occurs when microorganisms consume susceptible organic substrate as a part of their own metabolic process. They are fundamental to the decomposition of natural materials. Natural fermentations have played a vital role in human development and are probably the oldest form of food preservation. The growth of microorganisms in foods is undesirable and considered spoilage, some fermentations are highly desirable. The various preservation methods are based on the application of heat and cold, radiation, removal of water, and other principles.

Types of  Fermentation in Food Processing 

Acetic, lactic, and alcoholic are three important kinds of fermentation involved in fruit and vegetable preservation. The keeping quality of vinegar, fermented pickles, and alcoholic beverages depends upon the presence of acetic acid, lactic, and alcohol, respectively. Care should be taken to exclude air from fermented products to avoid further unwanted or secondary fermentation. Wines, cider, vinegar, fermented pickles, and other fermented beverages, etc., are prepared by these processes.

Acetic acid fermentation

• Wine
• Cider
• Malt
• Honey

Lactic acid Fermentation in food Processing

• Cucumbers- Sour Pickles, salt stock
• Tomato- pickles
• Lemon-Pickles
• Mango- Pickles
• Cauliflower-Pickles
• Olives- Green olive, ripe olive
• Cabbage- Sauerkraut
• Turnips- Asuerruben
• Lettuce-lettuce
• Mixed Vegetables-Turnips, radish, cabbage, Paw Tsay
• Coffee Cherries-coffee, beans
• Vanilla Beans-vanilla

Lactic acid bacteria with other organisms

• With yeast
• With Mould

Alcoholic Fermentation in food Processing (Yeast)

• Fruit wine
• Malt- beer, ale, porter, stout, block, pilsner
• Wines- brandy
• Grain mash- whiskey

Yeast with lactic acid bacteria

• Ginger beer
• Beans-vermicelli

Yeast with acetic acid bacteria

• Cocoa beans
• Citron
  

  Acetic acid fermentation Fermentation in food Processing

  The production of vinegar (acetic acid) from fruit juices is perhaps one of the oldest organic acid fermentations known. Acetic acid is produced by the oxidation of ethyl alcohol by bacteria such as Acetobacter aceti, a orleansis, Schtzenbachi, and others. Theoretically, 100 parts of sugar (sucrose or maltose) should yield about 51 parts of ethyl alcohol or 67 parts of acetic acid. In actual practice, however, even under the most favorable conditions, 43 to 48 parts of alcohol or 67 parts of acetic acid only are produced. These losses in yield may be due to the consumption of sugar in the solution by the yeast. Losses of alcohol and acetic acid due to evaporation and oxidation. Losses due to utilization by acetic acid bacteria for their growth.
  Hence, it is necessary to use a juice with at least 10 percent (maltose/sucrose) content for the preparation of vinegar of about 5 percent acetic acid bacteria attack the acid itself. This can be prevented by filling the containers up to the brim and sealing them airtight.

 

Lactic acid Fermentation in food Processing

Lactic acid fermentation as a good method of preservation is another ancient art of unknown origin. It was investigated by Pasteur. Lactic acid fermentation is an anaerobic intra-molecular oxidation-reduction process. Both homofermentative and heterofermentative lactic acid bacteria participate in food fermentation. In some cases, yeasts and moulds also participate along with lactic acid bacteria. bacteria prefer low acid medium for their growth. The lactic acid bacteria, however, can grow in an acid medium and can also produce acid through their action on the substrate. They can grow in the presence of 8-10 percent salt. Advantages are taken of these two factors in pickling. undesirable organisms’ growth is inhibited by adding salt.

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Fermentation in food takes place fairly well in brine containing approximately 5 percent salt but proceeds somewhat slowly with 10 percent salt. To some extent, it continues up to 15 percent, but at 20 percent, all fermentation stops. It is therefore, customary to place the vegetables in a 10 percent salt solution to allow lactic acid fermentation to take place and then increase the concentration of salt gradually so that by the time the pickle is ready, the concentration would have reached 15 percent.

Temperature is another important factor (lactic acid fermentation). Lactic acid bacteria are most active at about 30 degrees. It is, therefore, essential that the temperature of the product undergoing lactic acid fermentation should be kept as close to 30 degrees as possible, especially in the beginning.
The sugar serves as food for lactic acid bacteria, which converts them into lactic and other acids. In practice 2-3 kg of salt is mixed with every 100 kg of material and the mixture is allowed to stand for 12-24 hours. When sufficient juices come out from the material to form the brine containing 5 percent salt.

Alcoholic Fermentation in Food Processing

Ethyl alcohol can be produced by fermentation of any carbohydrates containing a fermentable sugar, or a polysaccharide that can be hydrolyzed to a fermentable sugar, cider is one of the examples of alcoholic fermentation. It is brought about by yeasts.
Here sugar is the substrate and the process is anaerobic. Saccharomyces cerevisiae is commonly employed for fermentation. It is imperative that the yeast must have a high tolerance for alcohol and must grow vigorously and produce a large quantity of alcohol.

100 g of hexose sugar should yield 51.1 g of ethyl alcohol and 48.9 g of carbon dioxide. Besides alcohol, a number of other substances are formed in small quantities. The alcohol content of wine is usually expressed as volume percent, i.e., cc of alcohol per 100 cc of wine. The percentage of alcohol will be Approximately equal to the brix (total soluble solids) of the crushed material multiplied by a factor of 0.57, e.g., a crushed material containing 22 percent total soluble solids should give theoretically and dry wine of about 22 into 0.57=12.5 volume percent of alcohol (v%)