Food Fermentation

Fermentation is one of the oldest ways of preservation food products with desirable properties such as extended shelf-life and good organoleptic properties. It is an essential metabolic phenomenon that basically takes place in absence of oxygen (O2).

Fermented foods are staples of the human diet and usually have an improved microbial stability and safety. In addition, some can be stored even at ambient temperatures. Furthermore, there are several examples of fermentation processes which lead to an increase in nutritional value or digestibility.

Fermentation happens commonly in yeast and bacteria and also in oxygen-starved muscle cells, as in the case of lactic acid fermentation. Microorganisms are integral part of the processing system

during the production of fermented foods. In terms of microbiologists, fermentation is a primary means of producing ATP by the degradation of organic nutrients anaerobically, in presence of suitable microorganisms.

Science of fermentation is called zymology. Research shows that fermentation processes have been developed in order to preserve foods for times of scarcity by preserving the food by organic acid and alcohols at the same time it imparts desirable flavor, texture to foods, reduce toxicity and decrease cooking time.

Fermentation is employed in the production of foods and its major roles including:
(1) Preservation of food through formation of inhibitory metabolites such as organic acid;
(2) improving food safety through inhibition of pathogens or removal of toxic compounds;
(3) improving the nutritional value and also makes the food palatable by enhancing its aroma and flavor.
Food Fermentation

Fermentation process of wine

Fermentation is a viable technique in the development of new products with modified physicochemical and sensory qualities, especially flavor and nutritional components

Alcoholic fermentation is widely employed for the preparation of beverages in which alcohol is major constituent. The conversion of grape juice to wine is a biotechnological tradition dating back to the dawn of civilization. Throughout the ages numerous winemaking strategies were developed resulting in the range of wine products, from champagne to port, available today.

Wine is an alcoholic beverage produced by the fermentation of sugars in fruit juices, primarily grape juice. In general, wines are classified into two types based on alcohol content: table wines(7 percent to 14 percent, by volume) and dessert wines (14 percent to 24 percent, by volume).

Fermentation is a relatively efficient, low energy preservation process which increases the shelf life, and decreases the need for refrigeration or other forms of food preservation technology. It is, therefore, a highly appropriate technique for use in developing countries and remote areas where access to sophisticated equipment is limited.

Fermented fruit wines are popular throughout the world, and in some regions, it makes a significant contribution to the diet of millions of individuals.

White wine fermentations are typically carried out for roughly one to two weeks at temperatures around 10 to 18 °C. Upon consumption of available glucose and fructose, the main sugars in grape juice, the wine is considered “dry” and separated from the yeast and grape lees (sediment).

Red wines are produced slightly differently than white wines. Like white wines, the alcoholic fermentation commences either through the action of indigenous yeasts or via direct inoculation of a starter culture. During the fermentation the grape material tends to float to the top of the vat forming a “cap.” To better enable extrac-tion of red pigments and to influence wine flavor, winemakers typically punch down the cap or pump juice from the bottom over the cap.

Although residual sugars are of obvious importance to the sweetness of wine, fermentable sugars in grapes are absolutely essential for fermentation. The single most signifi cant by-product of fermentation is ethanol. In addition, sugars may be metabolized to higher alco-hols, fatty acid esters, and aldehydes.

Fermentation occurs in vats of stainless steel, lined concrete or wood. Fermenting at too low a temperature inhibits extracting the best material from the grapes; too high and aromatic and flavor complexity are lost.

The products of fermentation are as follows: Alcohol, glycerol, and carbon dioxide are obtained from yeast fermentation of various sugars; Butyl alcohol, acetone, lactic acid, monosodium glutamate, and acetic acid are products of bacteria action; and citric acid, gluconic acid, antibiotics,

After fermentation, all wines undergo a period of adjustment (maturation) and clarification prior to bottling. The process of maturation involves the precipitation of particulate and colloidal material from the wine as well as a complex range of physical, chemical, and biological changes that tend to maintain and/or improve the sensory characteristics of the wine.

Fermentation process of wine

Process of pickling

Pickling is a traditional craft that has been practiced for generations. There are a few different methods for pickling various types of foods: by using vinegar, salt or brine.

Vinegar
Pickling preserves food by acidification of food products through the addition of acid and/or fermentation. The preferred solution for pickling is distilled vinegar.

Vinegar is often used because the acidity of the vinegar keeps many microorganisms in check. Pickling changes the texture, color and flavor of the vegetables like cucumbers to create pickles.

Salt
Pickling using salt is primarily a method used for fermentation. Salt is used to process foods as cabbage that once salted has enough natural moisture to produce a brine.

The amount of salt in the brine is carefully adjusted so that the brine will ferment and produce lactic acid, the substance that actually performs the pickling.
Process of pickling