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Quadrant 3 Rancidity & Storage of Fats

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Quadrant 3 Rancidity & Storage of Fats Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS35 Rancidity and Storage of fats Name of the Content Writer: Dr. Aruna Palta Quadrant 3 Rancidity & storage of fats Interesting Facts No. Interesting Facts 1. Lipid oxidation in one of the major causes of food spoilage. It leads to the development off-flavours and off-odours generally called rancidity. 2. Auto oxidation is the reaction of fats and oils with molecular oxygen. It consists of three steps namely, initiation, propagation and termination. 3. Volatile aldhehydes formed during autoxidation are mainly responsible for the rancid flavour of fats and oils. 4. The number, position and geometry of double bonds in the fatty acid chain affect the rate of oxidation. As the number of double bonds increase, there is an increase in the rate of oxidation. 5. Hydrolysis of ester bonds in lipids can occur by enzyme action, heat and moisture, resulting in the liberation of free fatty acid. 6. Lipid oxidation at high temperature involves both thermolytic and oxidative reactions leading to loss of flavor, appearance and nutritive value. 7. Antioxidants can delay the onset, or slow the rate of oxidation of fats and oils. Glossary Starting Term Definition Related Character term Rancidity The development of any disagreeable odour and flavor in fats & oils is called Rancidity. Autoxidation The spontaneous uptake of oxygen by the unsaturated oils exposed to air is known as autoxidation. Reversion Many fats & oils undergo a change in flavour before becoming Rancid. This change in flavour is different from the Rancid flavour & is known as reversion. Antioxidants They are substances which take up oxygen, gets oxidized and thereby prevent rancidity. Lipolysis The process of breakdown of lipids as a Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS35 Rancidity and Storage of fats Name of the Content Writer: Dr. Aruna Palta result of which free fatty acids are released. Polymerization After lipolysis the free fatty acids form polymers, the viscosityof the fat increases, the colour darkens and the quality of the fat deteriorates. Induction period This is the period when the fats gradually take up oxygen from the air but off flavour is not detected. Learn More / Web Resources/ Supporting Materials Foods Facts and Principles: N. Shakuntala Manay, M.Shadaksharaswamy third revised edition. New Age International(P) Ltd. Publishers 2008 McWilliams M. (2007). Nutrition and Dietetics 8th edition. Pearson Education Inc; 2006 Kilcast D, Subramaniam P. (2000). The Stability and shelf life of food. Cambridge, England: Woodhead Publishing Limited; 2000 Introductory Food Chemistry: Ira D Garard The AVI Publishing Company, INC. Westport, Connecticut 1976. Foods: Experimental Perspectives: Margaret McWilliams,1989. Food Science: B. Srilakshmi, New age International Publishers,2009. http://foodstorage.pbworks.com https://en.wikipedia.org/wiki/Rancidification http://www.naturalproductsinsider.com/articles http://survivalblog.com/fats_and_rancidity_a_food_storage_problem_by_l_joseph_mountain/ Points to Ponder No. Points to Ponder 1 Tocopherols and ascorbic acid are excellent antioxidants. 2 To prevent fat from going rancid it should be stored in an airtight container away from light. 3 Fish oils deteriorate most rapidly. 4 Pro-oxidants increase the rate of oxidation . 5 Fats undergo chemical decomposition when exposed to heat in presence of oxygen. Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS35 Rancidity and Storage of fats Name of the Content Writer: Dr. Aruna Palta .
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