Foreword The book “Probiotics and Their Role in Improving Human Health” authored by Dr. Renu Agrawal aims at creating awareness about probiotics and their importance in leading a healthy balanced life. Probiotic  have made a special place in human nutrition and therapy as they are natural and fall under the GRAS category. There is something novel and new happening in this area of research everyday, so that there is a need to have all the data compiled and updated from time to time to help the researchers and the population at large. A century of research in this area resulted in several probiotic products which are now available in the market . This book aims at enlisting the various developments which have taken place in the field starting from isolation of microbes to the health implication which probiotics can bring about. Today a number of products have come into the market. The medical practitioners are also recommending probiotic in different forms to the patients especially affected by new life style diseases obesity, diabetes, cardiovascular diseases and overweight. In fact the scientists are working on probiotics since a century. Today, it has come a long way with the recent developments in formulation manufacture, packing, storage and marketing.

Newer technologies involve fermentation by specific strains of lactic acid bacteria which bring specific fermentation under controlled conditions to a specific fermented product with enhanced organoleptic, nutritional and therapeutic qualities. Today health is of primary concern. It is important to have nutritionally balanced food with good bacteria. For this, probiotic foods top the list. The functional food concept was initially developed in Japan in 1990‘s as there were many side effects of allopathic medicines. A regulatory system has been initiated by the ministry of health and welfare to approve certain foods to improve health. These are now recognized as Foods for specialized health use (FOSHU). According to American dietic association (ADA) these foods are potential healthful food or food ingredients that may provide health benefits beyond the traditional nutrients. Probiotics are beneficial microorganisms. Probiotic foods as yogurt and sauerkraut are very well known. Fermentation increases the nutrient content and taste with the shelf life.

There are potential beneficial medicinal uses of probiotics for which research is limited and only preliminary results are available. Recent research on the molecular biology and genomics of Lactobacillus has focused on the interaction with the immune system, anti-cancer potential, and potential as a biotherapeutic agent in case of antibiotic-associated diarrhoea, traveller‘s diarrhoea, pediatric diarrhoea, inflammatory bowel diseases and irritable bowel syndrome (Ljungh et al., 2009). Studies of some probiotics tested in vitro on human epithelial cell lines have shown that they could block the adhesion of shiga toxin producing E. coli (Sherman et al., 2005). These are claimed to be health promoting and/ or disease preventing beyond the basic function of supplying nutrients. Probiotic foods are emerging as an important category of food supplements. Earlier workers have shown the inhibition of diarrhea caused by E.coli using probiotic lactic acid bacteria and yeast (Yan and Polk, 2006). Ratledge et al. (2002) have studied the biochemistry and molecular biology of lipid accumulation in oleaginous microorganisms.

LAB constitutes a group of gram positive bacteria. They are nonsporulating, nonrespiring but aerotolerant cocci or rods, which produce lactic acid as one of the main fermentation products of carbohydrates, they do not have cytochromes. They belong to the phylum Firmicuttes, class Bacilli and order Lactobacillaceae. The group includes several genera such as Lactobacillus, Lactococcus, Bifidobacterium, Pediococcus, Enterobacter, Corynebacterium, Streptococcus, Leuconostoc etc.

4a. Intestinal Disorders   History of health claims   According to Bottazzi (1983) it was in 76 BC that the Roman historian Plinius recommended the use of fermented milk for treating gastroenteritis. Metchnikoff claimed that the intake of fermented milk containing Lactobacilli reduces the toxin producing bacteria, thereby increasing the longetivity of the host (Metchnikoff, 1908). Tissier (1905) showed that there was an increase in the Bifidobacteria in breast fed-infants, thus claiming that the administration of Bifidobacteria to infants suffering from diarrhea was very beneficial as they supersede the putrefactive bacteria that causes the disease. Intestinal beneficial microfloras are responsible to resist the disease (Bohnhoff et al., 1954).

The lack of mechanistic understanding of probiotic activity is a major drawback for the prediction of safety of probiotic intervention. The complex gut-associated microbial ecosystem and nutritionally related factors are the most important environmental triggers for the development and modification of chronic degenerative diseases including immune and metabolic pathologies. In fact, the interaction between the gut microbial ecosystem and the host is considered to be a critical factor in overall health or disease. Whether probiotics will exert protective, harmful, immune-stimulating or immune-suppressing effects on a host is dependent on the interaction between the microbial signals, the genetic make-up of the host and the effects by the environment. Many studies have revealed that certain probiotic bacteria stimulate immune cell proliferation and activity as evidenced by the production of cytokines and antibodies, thereby enhancing the effectiveness of the immune response against pathogens. Ng et al. (2009)

Probiotic Fermented food products   An individual requires adequate nutrients like proteins, carbohydrates, vitamins, and minerals to maintain diet. There has been an explosion of the consumer interest in the role of enhancing the health by some specific foods or physiologically active food components, so called functional foods (Hasler, 1998). The concept of functional foods evolved in the year 1990 in Japan.

Antibiotic Resistance and Gene transfer   It is important that probiotic strains should be assessed for their phenotypical antibiotic resistance and potential to transfer resistance gene as otherwise they cannot be used in food (BgVV, 2000; Vankerckhoven et al., 2008). It is vital to do research on characterization of acquired resistance mechanisms and transferability of resistance genes and on methods for determining transferability.

Probiotics are measured in colony forming units (cfu). CFUs are generally measured in the millions or billions per serving. Probiotics are most commonly beneficial bacteria, but can also be friendly fungal or other organisms, that are typically freeze dried to stabilize them in an inert state during storage and production. Then their continued stability and viability, as measured by CFU counts when cultured, is dependent on limiting their exposure to stimulating environmental conditions such as temperature and moisture. Besides refrigeration, this protection can be done by packaging in glass or by adding freshness packets that helps to absorb and reduce moisture in the package.

What new research is needed, what trials and how will the ultimate consumer and Industry benefit?   In Brazil, the sales of functional foods amounts to US $ 500 million per year representing about 1% of the total sale of the Brazilian food processing industry. According to a report the interests are mainly for dairy products, nutraceuticals and soy-based products. ABIA forecasts a substantial growth of 4.5-5% for this segment of the market (Stanton et al., 2001). In order to exert the health benefits beyond inherent basic nutrition, it is necessary that the activity of the probiotic culture should be maintained at very high levels during the shelf life of the product.

In spite of the problems with dosage and viability of probiotic strains, a lot more work is required for industry standardization and safety issues. However, it is noted that probiotics have considerable potential against many pathogenic and other diseases. A wide range of clinical trials are still needed to standardize and optimize the conditions. Ongoing basic research will continue to identify and characterize existing strains of probiotics, identifying strain-specific outcomes, determine optimal doses needed for certain results and assess their stability through processing and digestion.

Today it has been understood that yeasts have great potentials as novel probiotics (Nayak, 2011). They have been found to be safe for human consumption in traditional fermented foods (Jakobsen and Narvhus 1996). Yeasts have a great physiological importance inside the gastrointestinal (GI) tract (Czerucka et al., 2007; Gatesoupe, 2007). Jespersen (2003) has mentioned the role of consuming fermented foods and the health benefits attributed with it.Yeasts are known for prevention of table olive (Arroyo lopez et al., 2012). Bonatsau et al. (2015) have shown multi-functional property of yeast as starters.

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