Fermented Foods and Their Production

Introduction

The traditional fermented foods made in the Orient which includes Japan, Indonesia, India, Pakistan, Thailand, Philippines, Taiwan, China, Korea, and the encompassing areas were produced long before written history. There was an extensive research dealing with fermented foods and drinks from 1878. The studies between 1881 and 1914 were devoted to isolation and description of the new microorganisms associated with the fermentation and also the fermented products. The renewed interest in the fermented foods now is concerned with nutrition, natural foods, expand export markets and add products to convenience foods to add zest and flavor. Traditional fermented foods are popularly consumed and form an integral part of our diet since early history. These can be prepared in the household or in cottage industry using relatively simple techniques and equipments (Aidoo et al., 2006). It is one of the oldest and most economical methods for producing and preserving foods. In addition to preservation, fermented foods can also have added benefits of enhancing flavour, increased digestibility, and improving nutritional and pharmacological values (Jeyaram et al., 2009). Lactic acid bacteria (LAB) perform an essential role in the preservation and production of wholesome fermented foods. Homo-fermentative and hetero-fermentative LAB are generally fastidious on artificial media, but they grow readily in most food substrates and lower the pH rapidly to a point where other competing organisms are no longer able to grow. Leuconostocs and Lactococcus generally lower the pH to 4.0 –4.5 and some of the Lactobacilli and Pediococci lower it up to 3.5 (Steinkraus, 1983). India is traditionally rich in fermented foods. In the Indian sub-continent, fermented foods are very common. The nature of the products and base material varies from region to region (Sekar and Mariappan, 2007). At present, there are hundreds of fermented foods with different base materials and preparation methodology. Each fermented food is associated with a unique group of microbiota, which increases the level of proteins, vitamins, essential amino acids and fatty acids. However, fermented foods are still produced traditionally by spontaneous fermentation and only limited knowledge has been obtained regarding the microbiota of these products (Jeyaram et al., 2009).

India, being a huge country has been the home of innumerable religious order of human population and diversity in climatic conditions which has resulted in a large number of fermented foods.

Since the beginning of human civilization there has been an intimate companionship between the human being and the fermentative activities of microorganisms. These fermentative activities have been utilized in the production of fermented foods and beverages, which are defined as those products that have been subordinated to the effect of microorganisms or enzymes to cause desirable biochemical changes. The microorganisms responsible for the fermentation may be the microflora indigenously present on the substrate, or they may be added as starter cultures (Harlander, 1992).

Fermentation is one of the oldest and most economical methods of producing and preserving food (Billings, 1998 and Chavan and Kadam, 1989). Ever since, the technologies for the industrial production of fermented products from milk, meat, fruits, vegetables and cereals are well developed recently and scientific work is actively carried out all over the world (Hirahara, 1998 and Pagni, 1998).

Fermented foods are produced using various manufacturing techniques and microbes. However, there are only four main fermentation processes: alcoholic, lactic acid, acetic acid and alkali fermentation (Soni and Sandhu, 1990). Alcohol fermentation results in the production of ethanol, and yeasts are the predominant organisms. Lactic acid fermentation (e.g. fermented milks and cereals) is mainly carried out by lactic acid bacteria. The other group of bacteria of importance in food fermentations are Acetobacter species, which convert alcohol to acetic acid under aerobic condition (McKay and Baldwin, 1990).