Abstract : Prebiotic are called Colonic foods which encourage the growth of favourable bacteria. Some of the known prebiotics include lactulose, lactitol and oligosaccharides. The benefits and functionality of probiotics can be improved by careful selection on the right prebiotic called synbiotic application . Lactulose a synthetic disaccharide is fermented by the colonic microflora resulting in changes in bacterial composition and metabolic activities of the colonic flora. Tagatose alters the composition and population of colonic microflora. Inulin and oligofructose are preferentially fermented by bifido bacteria creating a by-product of short-chain fatty acids. Prebiotics act in several ways to help prevent pathogen colonization and translocation. Insoluble dietary fibre (e.g.cellulose) reduces gut transit time and increases faecal volume, while it might get metabolised by the intestinal microflora. However , soluble dietary fibre gets highly metabolised by the gut microflora and results in: a) acidification of the intestinal content, b) production of short chain fatty acids (SCFA) and gases and c) increase in faecal bacterial mass and faecal volume (Roberfroid, 2007). Specific oligosaccharides and polysaccharides are metabolised by Lactobaccillus and Bifidobaterium, resulting in an increase in their numbers and beneficial activity in the gut. Prebiotics are also useful for their application in food science. Type of sugar moieties and the molecular weight of the prebiotic molecule, determine their selective or non-selective fermentation by the intestinal microflora. The oligosaccharides could prevent attachment of pathogenic bacteria to the intestinal enterocytes by blocking the bacterial lectins. They represent an opportunity for the fortification of the indigenous microflora with its beneficial members through functional diet.
Keywords: Functional foods, prebiotics, inulin, oligosaccharides