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Lipid Oxidation

Lipid Oxidation. FDSC400. Types of Rancidity. Hydrolytic rancidity Lipase Free fatty acids provide aroma Oxidative rancidity Radical oxidation Aldehydes and other compounds provide aroma. Oxidative Rancidity. Part 1: Form lipid hydroperoxides Part 2: Break down lipid hydroperoxides.

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Lipid Oxidation

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  1. Lipid Oxidation FDSC400

  2. Types of Rancidity • Hydrolytic rancidity • Lipase • Free fatty acids provide aroma • Oxidative rancidity • Radical oxidation • Aldehydes and other compounds provide aroma

  3. Oxidative Rancidity • Part 1: Form lipid hydroperoxides • Part 2: Break down lipid hydroperoxides

  4. Oxidative Rancidity • Initiation • A radical is formed • Propagation • Radicals react and transfer their unpaired electron to other compounds • Termination • Two radicals combine to stop the reaction

  5. The Pentadiene Structure RH R H . …Radical Migration

  6. Addition of Oxygen - Propagation - . . R +O2 ROO ROO +RH ROOH +R . . Each methylene interrupter can lead to three possible lipid hydroperoxides!

  7. Termination

  8. Part 2: Hydroperoxide Breakdown (1) (2)

  9. Factors affecting rate • Fatty acid composition • Temperature • Water activity • Metal ions • Oxygen • Light

  10. Metal chelatorscitrate, EDTA Radical scavengers (primary and secondary) BHA, BHT, tocopherol Antioxidants

  11. Radical Scavenging Antioxidants

  12. e.g.: w3 PUFA Supplemented Yogurt water w3 oil Homogenize Pasteurize Store/ship w3 emulsion milk Culture ingredients Pasteurize Homogenize Pack Ferment Store

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