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Lecture 5

AGRC 112 Lecture Notes - Lecture 5: Canola, Crystallization, HexanePremium

2 pages93 viewsWinter 2017

Department
Agriculture
Course Code
AGRC 112
Professor
Takaya Kunio
Lecture
5

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Oilseeds
Fats and Oils
-Fats are solids at room temperature and oil are liquids
-They are edible or inedible
-Some plants are edible but humans can not eat them due to digestibility
-Vegetable and animal sources
-Our focus —> edible vegetable oils
-The principal animal fats are:
-Tallow, lard, butterfat - concerns with respect to saturated fatty acids
-Marine oils - consumption recommended due to content of long chain, polyunsaturated
( omega-3) fatty acids
The chemistry of fats and oils
-Edible fats and oils are mixtures of triacylglyerols (triglycerides, TGs)
-Triglycerides consist of glycerol linked ( esterifies) to three fatty acids (FA) molecules
-Triglycerides may be simple or mixed
Fatty acids
-Hundreds exist in nature - a dozen or so are important in vegetable oils, 5 or 6 predominate in
most edible oils
-Consists of unbranched linear chain, 2 to 23 carbons in length with an acid ( carboxyl) group
at one end
-Chains may be saturated or unsaturated, contain none, one or several C=C double bonds
-In most polyunsaturated fatty acids, double bonds are separated by CH2 groups ( non-
conjugated)
-The conjugated ones will go rancid faster
-The non conjugated has better oxidation
Melting points of fatty acids
-Melting point increases as the carbon chain length increases
-Melting point decreases as the number of double bonds ( degree of unsaturated ) increases
-Effect of unsaturation on melting point is much greater then that of chain length
-Linolenic acid will go rancid faster because it is not stable so it will oxidize and attract oxygen
faster
Fats and oils
-Liquid oils contain predominantly unsaturated fatty acids
-Solid fats contain predominantly saturated fatty acids or a mixture of saturated and
unsaturated fatty acids
-Lipids with a larger proportion of unsaturated fatty acids are more susceptible to thermal and
oxidative breakdown
Fatty acids
-C=c bonds are in cis configuration unless fat or oil has been hydrogenated
-Hydrogenation is a conventional process used to convert liquid vegetable oils into solid or sell
solid fats such as those present in shortenings and hard margarines
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