Transcript Lipid Oxidation - Information technology

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
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
The Pentadiene Structure
H H H
C C C C C
H H H
RH
R
.
H
…Radical Migration
Addition of Oxygen
- Propagation R
.
+O2
.
ROO +RH
ROO
ROOH
.
+R .
Each methylene interrupter can lead to three possible lipid hydroperoxides!
Termination
Part 2: Hydroperoxide Breakdown
(1)
(2)
Factors affecting rate
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Fatty acid composition
Temperature
Water activity
Metal ions
Oxygen
Light
Antioxidants
• Metal chelators
• Radical scavengers
(primary and
secondary)
citrate, EDTA
BHA, BHT, tocopherol
Radical Scavenging Antioxidants
e.g.: w3 PUFA Supplemented
Yogurt
w3 oil
water
Homogenize
Pasteurize
Store/ship
w3 emulsion
Pasteurize
milk
Homogenize
Culture ingredients
Pack
Ferment
Store