Lactic Acid In Milk

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The lactic acid bacteria (LAB) are either rod-shaped (bacillus), or spherical (coccus), and are characterized by an increased tolerance to acidity (low pH range). This aspect helps LAB to outcompete other bacteria in a natural fermentation, as they can withstand the increased acidity from organic acid production (e.g., Lactic Acid). LAB can be found in spoiling plants and lactic products which produce lactic acid as the major metabolic end product as a result of carbohydrate fermentation. This characteristic has, throughout the history, associated LAB with fermented food industry, as acidification impedes the growth of other microbial spoilage organisms. Several strains of LAB produce proteinaceous bacteriocins that create an additional hurdle…show more content…
So universal is this phenomenon that it is generally regarded as an inevitable change which cannot be avoided and as already pointed out has in the past been regarded as a normal property of milk. Today however the phenomenon is well understood. It is due to the action of the certain of lactic acid and this acid gives which converts into milk bacteria upon the milk sugar which converts it into lactic acid and this acid gives the sour taste and curdles the milk. After this acid is produced in small quantity its presence proves deterious to the growth of the bacteria and further bacterial growth is checked. After souring therefore the milk for some time does not ordinarily undergo any further changes. Milk souring has been commonly regarded as a single phenomenon alike in all cases. When it was first studied by bacteriologists it was thought to be due in all cases to a single species of micro-organism which was discovered to be commonly present and named Bacillus acidi lactici. This bacterium has certainly the power of souring milk rapidly, and is found to be very common in diaries in Europe. As soon as bacteriologists turned their attention more closely to the subject it was found that the spontaneous souring of milk was not always caused by the same species of bacterium. Instead of finding this Bacillus acidi always present, they found that quiet number of different species of bacteria have the power of…show more content…
(b) Fermentation of milk with proteolysis starter cultures and (c) Through the action of enzymes derived from proteolysis microorganism. During controlled fermentation of milk with certain dairy starters, peptides with various bioactivities can be formed and are detected as an active form even in the final products, such as fermented milks and cheese (Meisel et al., 1999). Bioactive peptides have been defined as peptides with hormone- or drug like activity that eventually modulate physiological function through binding interactions to specific receptors on target cells leading to induction of physiological responses. According to their functional properties, bioactive peptides may be classified as antimicrobial, antithrombotic, antihypertensive, opioid, immunomodulatory, mineral binding and antioxidative. These peptides play an important role on human health (Shrikant Sharma et al., 2011). 2.9 Fermentation conditions affecting the bacterial

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