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Role of Microbes in Fermented Food
#9
This review outlines the role of lactic acid bacteria in many such fermentations and the mechanisms of antibiosis with particular reference to bacteriocins and gives a brief description of some important fermented foods from various countries. It is anticipated that the contribution of the advances in lactic acid bacteria research towards improvement of strains for use in food fermentation will benefit both the consumer and the producer.
#10
From the ancient times, fermentation is used as a technique for food preservation. Through fermentation not only the shelf life of the food product is increased along with its microbiological safety, but also the digestibility of the food gets increased. In a few cases (cassava fermentation) even the toxicity of the substrate is reduced.
Starter cultures are the basis of fermented food production. One example is lactic acid bacteria which rapidly increases the acidity of the substrate. Use of lactic acid bacteria in food fermentation is one of the oldest forms of food preservation technique used by mankind. But only recently it received much important scientific attention. Lactic acid bacteria have been used safely for long years and shown no pathogenic properties, thus can be considered as a commercial microorganism. The lactic acid bacteria possess exclusive metabolic properties enabling it to be involved in various fermentation processes of vegetables, milk, meats and cereals. A traditional fermentation technique depends on inoculation from the preceding batch starter cultures. But modern industrial fermentation processes use commercially available inoculums for consistent products. The potential of lactic acid bacteria provided the essential impetus towards the development of its industrially significant strains. Many such strains with industrially important functionality are coming up. Industrially important lactic acid bacteria are used for the production of sugar polymers, antimicrobial substances, aromatic compounds, enzymes, vitamins and even different probiotics. They have the capability to produce important bacteriocins that can act as a food preservative to enhance its shelf life and thus improves its safety.
Both the consumers and producers will be benefited if proper contribution is carried out for the advancement of research towards strain improvement of lactic acid bacteria to be used in food fermentation. Consumer awareness is increasing every day. Diet and health are now linked together by the modern day consumers.
Consumers are now looking to include Probiotics i.e. microbial food supplements having beneficial health effects in their daily diet. Fermented products of lactic acid bacteria comprise most of the probiotic market in the form of curd, yogurt, etc. Probiotics improves the immune system, keeps the intestinal tract healthy, decreases allergies and lactose intolerance and even reduces cancer risks.
Though there is no strong suggestion on the mechanisms of actions of probiotics but may involve antimicrobial product formation, competing with the pathogens for receptors and nutrients, modification of gut pH, stimulating immune cells and lactase production.
Thus fermentation with the help of microorganisms plays important roles in human life, not only through food preservation, but also through the addition of beneficial and essential nutritional factors. Fermentation provides a cost effective, safe and natural approach towards food preservation and healthy diet.
#11
As a previous poster mentioned, it is important to be aware of the bacterial content of foods in which fermentation is a feature and to ensure purity of culture in producing such foods. One response to the original post gives a comprehensive overview of some less well known fermented foods and their purported health benefits. Among the foods mentioned were the Nepalese-derived gundruk and sinki. Gundruk is derived from lactic-fermentation of leaves of mustard/radish/cauliflower while sinki is derived from radish root. The microbial content of samples of these foods has been assessed both phenotypically and also genotypically by RAPD-PCR, repetitive element PCR and species-specific PCR techniques. As would be expected, there are substantial lactic acid bacteria populations in these foods. In one study, the major lactic acid bacterial representatives identified were Lactobacillus brevis, Lactobacillus plantarum, Pediococcus pentosaceus, Pediococcus acidilactici and Leuconostoc fallax (Tamang et al., 2005). Further studies from this research group addressed functional properties of lactic acid bacteria from gundruk, sinki and other ethnic fermented vegetables. Properties such as antimicrobial activity, acidification and coagulation activities and multiple enzymatic activities were identified (Tamang et al., 2009b). A recent review gives a comprehensive overview of Indian fermented foods, including gundruk and sinki, and their significance as sources of lactic acid bacteria (Satish Kumar et al., 2013). Another recent review  considers the importance of these types of food as probiotic sources (Swain et al., 2014). However, despite these apparent health benefits, it is important to be mindful of any potential risks associated with such foods. For example, in one study on the cytochrome P450 2E1 (CYP2E1) polymorphism and its role in increased risk of liver diseases in Northeast India, it was suggested that indigenous foods including Gundruk, which are high in nitrite and nitrosamine, might be an associated risk factor for liver disease in this region (Deka et al., 2010).

References:

Tamang JP, Tamang B, Schillinger U, Franz CM, Gores M, Holzapfel WH. Identification of predominant lactic acid bacteria isolated from traditionally fermented vegetable products of the Eastern Himalayas. Int J Food Microbiol. 2005; 105(3):347-56.

Tamang JP, Tamang B, Schillinger U, Guigas C, Holzapfel WH. Functional properties of lactic acid bacteria isolated from the ethnic fermented vegetables of the Himalayas. Int J Food Microbiol. 2009; 135:28–33

Satish Kumar R, Kanmani P, Yuvaraj N, Paari KA, Pattukumar V, Arul V. Traditional Indian fermented foods: a rich source of lactic acid bacteria. Int J Food Sci Nutr. 2013; 64(4):415-28. doi: 10.3109/09637486.2012.746288.

Swain MR, Anandharaj M, Ray RC, Parveen Rani R. Fermented fruits and vegetables of Asia: a potential source of probiotics. Biotechnol Res Int. 2014; 2014:250424. doi: 10.1155/2014/250424.

Deka M, Bose M, Baruah B, Bose PD, Medhi S, Bose S, Saikia A, Kar P. Role of CYP2E1 gene polymorphisms association with hepatitis risk in Northeast India. World J Gastroenterol. 2010; 16(38):4800-8.
 
 
 
 
 
 
  

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