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Introduction
Inability of human beings to digest lactose is often referred to as "Lactose-intolerance" and has been attributed to insufficient amounts of lactase in the small intestine to hydrolyze lactose consumed in the diet ([26] Littman and Hammond, 1965; [3] Bayless and Rosenweig, 1966). β-galactosidase, commonly known as lactase is capable of hydrolyzing β-D-galactoside bond between D-galactose and glucose. The enzyme is widely distributed in nature and has been isolated from plants, animals and microorganisms.
Lactobacilli is the normal resident of gastro-intestinal tract ([30] Mitsuoka, 1992) and capable of restoring the normal microbial balance in the intestine ([10] Garvie et al. , 1984); utilization of lactobacilli during the manufacture of cultured milk products are proposed to exhibit "health-promoting" or "probiotic" effect in humans, which include improvement of lactose digestion ([12] Gilliland, 1989). [47] Shahani and Chandan (1979) pointed out that cultured milk products may provide supplementary quantities of lactase and other constituent enzymes, elaborated by cultures during fermentation, contributing towards the assimilation of lactose by lactose-intolerant individuals.
In the present article, an endeavor has been made to enlighten the prophylactic aspect of cultured milk products, which render them more suitable for ingestion by lactose-intolerant recipients.
Significance of lactase enzyme
Lactose, a disaccharide composed of glucose and galactose, is the major solid component of milk and must be hydrolyzed into its components under the influence of enzyme lactase, a membrane bound enzyme present in the brush border of the small intestinal epithelial cell prior to its absorption by humans ([29] Miller and Brand, 1980; [18] Hourigan, 1984). In case the quantum of lactose ingested exceeds the hydrolytic capacity of the available intestinal lactase, the undigested portion of lactose is transported to the large intestine, where it increases the osmolarity of the intestinal fluids. Undigested lactose undergoes bacterial fermentation in the colon, generating organic acids, carbondioxide and hydrogen, which along with the large amount of water is drawn into the intestine, are primarily responsible for various symptoms such as bloating, flatulence, abdominal cramps, diarrhoea and loss of appetite ([18] Hourigan, 1984; [17] Hofi, 1990). Lactose maldigestion occurs due to either gastro-intestinal disease or physiological decline in the intestinal lactase activity and may lead to clinical symptoms of lactose-intolerance. [44] Semenza and Auricchio (1995) registered reduction in lactase...