n the present days the major part of World population are struggling with the issues of chronic diseases like cancer, cardiovascular diseases, hypertension, diabetes, obesity, arthritis etc. The root causes of these chronic diseases are the choice of poor life style and food habits which are responsible for alternation in the ecosystem and the normal microbiota in the gastrointestinal tract (GI) tract and causes abnormalities in the functioning of metabolic and immune system of the host. Therefore it is important to maintain the stability of the probiotics in the GI tract, to stimulate their function in the body, to avoid the application of chemical additives in the food products for improving their shelf life and to optimize the processing method for reduction of the raw material associated anti-nutritional factors, to reduce the risk of cardiovascular diseases are the challenging issues and these can be easily achieved by increasing the ratio of fermented food in the daily diet.
Fermented foods are source of both nutritive and non-nutritive components as well as both functional and non-functional microorganism. These functional microorganisms are responsible for the specific functional properties of the fermented foods. They transform the chemical constituents of the raw materials during fermentation and enhance the bio-availability of nutrients in the food, its sensory properties, impart bio-preservative effects by producing antioxidant and antimicrobial compounds. The filamentous molds in fermented foods are responsible for the degradation of anti-nutritional factors in the food products and improve its safety level. Functional microorganisms in fermented foods fortify the food with different bioactive compounds and synthesize nutrients like vitamin K and most of the water-soluble B-vitamins, such as cobalamin, foliates, pyridoxine, riboflavin and thiamine which help in improving the immunity of the consumer against harmful diseases and helps in prevention of cardiovascular diseases, allergic reactions, gastrointestinal disorders, diabetes etc. Fermented foods are also a greater source of probitics. They enhance and maintain the stability of probiotics and help in stimulating the functions of probiotic. The lactic acid bacterium in the GI produces lactic acid and reduces the pH which inhibits the growth of pathogenic bacteria as most of the bacteria are nutrophilic in nature.
The most common bacteria associated with fermented foods are Lactic acid group of bacteria (LAB) mostly species of Lactobacillus, Enterococcus, Lactococcus, Leuconostoc, Pediococcus, Weissella etc. Bacillus group of microorganisms are sourced from legume-based fermented foods like tempeh, soya sauce, idli, dosa, natto etc. Species of Brachybacterium, Bifidobacterium, Propionibacterium and Brevibacterium, are found in yogurt and cheese and species of Hafnia and Arthrobacter from fermented meat products. Yeast sourced from fermented foods are mostly include Debaryomyces, Candida, Hansenula, Geotrichum, Pichia, Kluyveromyces, Rhodotorula, Saccharomyces, Saccharomycopsis, Schizosaccharomyces, Torulopsis, Zygosaccharomyces and Wickerhamomyces,. The fungal species like species of Amylomyces, Actinomucor, Penicillium, Aspergillus, Monascus, Mucor, Neurospora, Rhizopus, and Ustilago are reported for many fermented foods.
Fig. Health benefits of fermented food products
Specific strains of bifidobacteria are potential therapeutic candidate for management of obesity. The high population of Bifidobacteria and low concentration of Staphalococcus aureus prevent excessive weight gain in infants. Therefore the breast feeded babies have lower risk of obesity. These are help in lowering the serum cholesterol level. The intestinal microflora synthesizes short chain fattyacid from indigestible polysaccharides by bacterial fermentation function as energy substrates, as well as regulates the satiety and food intake. Improve nutrient absorption and reduce the risk of obesity. The fermented foods like yogurt, cheese, fermented vegetables are the best source of bifidobacteria.
A large number of probiotics and secondary metabolites sourced from the Lactobacillus or Bifidobacterium have proved for having antidibetic properties. Bifidobacterium species significantly improved glucose-tolerance, glucose induced insulin secretion and normalized the inflammatory tone to reduce the risk of type-1 and type -2 diabetes. Lactobacillus acidophilus and L. casei improved glucose tolerance and hyperglycemia.
Improve the bioavailability of mineral
Probiotic bacteria improve the solubility of minerals due to production of short chain fatty acid by fermenting the non digestible polysaccharides which inhibits the absorption of minerals by binding with them. Fermentation of these polysaccharides releases these mineral and increase their availability for potential absorbtion. Bifidobacterium bifidum and longum, with FOS and GOS significantly increased calcium, magnesium, and phosphorus bioavailability. The synthesis of phytase improves the availability of phosphorus from phytate, cmmon form of phosphorus in legumes.
Anticancer Properties of fermented foods
Fermented foods are gaining recognition as an important anti-cancer adjunct. The functional micrflora found in fermented foods are effective in suppressing colon cancer and are also help in inhibiting brest, liver, small intestine and other organs cancers. These influences inflammation and immune function which play a critical role in cancer. Prolonged inflammation can damage body's healthy cells and tissue, and weaken immune system." Reducing inflammation is one important anti-cancer feature of fermented foods, because they contribute the beneficial microbiota to the gut microflora. The metabolite produces by them act as sources of energy and helps in regulating the person metabolism and reduce inflammation.
The microbial metabolism may affect the risk of cancer by influencing the metabolism and detoxification of carcinogens and DNA repair, by controlling the hormone regulation, cell death, microbial proliferation and differentiation. For example, butyrate, a short-chain fatty acid formed during the fermentation of the dietary fiber in he food products has been shown to induce apoptosis of colon cancer cells and fermented milk products may reduce the risk of bladder cancer. A diet with higher healthy fats and lower non-fiber carbohydrate may significantly reduce the risk of cancer by improving the mitochondrial and metabolic function. The probiotics like bifidobacterium and lactobcillus sourced from fermented milk products have been shown to induce changes responsible for increase in carbohydrate metabolism. Lactobacillus strains helps in preventing heavy metal toxicity by binding and excreting these metals. They have been shown to reduce the toxicity of heterocyclic aromatic amines (HCA), cancer causing compounds found in heat processed meats by scavenging them and by preventing their generation in situ. The Kimchi (fermented cabbage) sourced probiotics help in detoxification of organophosphorus pesticides attributed to phosphatase enzyme. It also breaks down sodium nitrate, a food preservative associated with increased cancer risk.
Recently it was observed that the disbalance in the gut microflora is responsible for high blood pressure in both human and animal. Supplementations with probiotics helps in reduce blood pressure. The mechanism of this antihypertensive effect of probiotics has not been fully understood. The ability of probiotics to reduce hypertension has been attributed to the release of bioactive peptides such as the angiotensin-converting enzyme inhibitory peptides takes place during the fermentation of food products.