lipids 4
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Type 2 oxidation causes primary oxidation products: What is the product and its characteristics?
hydroperoxides: 1. very unstable 2. non-volatile 3. odour/ tasteless
Type 2 oxidation causes secondairy oxidation products: What is the product and its characteristics?
carbonyl compounds (aldehydes/ ketones) 1. relatively stable 2. volatile 3. taste/smell
how does water determine the oxidation level?
low water activity (<0,2) extreme fast oxidation moderate aw (0,2-0,4) low oxidation rate higher aw (>0,4) higher oxidation rate
explain pro and anti oxidants
pro-oxidants: compounds stimulating fat oxidation (metal ions) antioxidants: slow down fat oxidation by removing radicals or oxygen from the reaction
name three methods for isolation of fat;
• pressing • solvent extraction • heating
what is the aim of refining?
removing impurities to convert the crude oil/ fat into more suitable end products (refined oil)
name the steps of refining oil:
• pre-treatment: filtering • removal of lecithin • degumming • deacidification • bleaching • deodorisation
modification to change th ephysical and chemical characteristics of fats:
• hydrogenation • interesterification • fractionation
unsatueated bonds in a liquid are saturated By? In presence of? also called?
• by means of hydrogen • in presence of a catalyst • is also called fat hardening
what catalysis hydrogenation? And will the structure change?
nickel during hydrogenation cis-trans isomerization of fatty acids take place
what is interesterification? What does it do to the fats/ oil?
In the presence of a catalyst, the position of the fatty acids within and between triglyceride molecules can be changed It changes the crystallization and melting behaviour
what is fractionation?
oils and fats can be separated by different melting points
what happens during winterization?
the high melting triglycerides and/ or waxes are removed