07-Fats+_+Oils_F_13

The worlds shortest and oversimplied explanation of

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Unformatted text preview: aporate Can be heated to very high temperatures Heat transfer with hot fat is called: frying FST10 ©GMS/GFR 2013 Fats, Double Bonds & Saturation (everything you were afraid to ask) ! The world’s shortest (and oversimplified) explanation of double bonds, saturation and unsaturation follows ... HH HH HCCH HCCH HH Ethylene Double Bond Ethane Single Bond FST10 ©GMS/GFR 2013 FST10 ©GMS/GFR 2013 See also McGee C-18 Fatty Acids COOH 18:0 — Stearic Acid COOH 18:1 — Oleic Acid COOH 18:2 — Linoleic Acid COOH 18:3 — Linolenic Acid OMEGA numbers & saturation What’s with the OMEGA numbers? ! Nutritionists are interested in the end of the molecule farthest from the acid group ! So the “last carbon” is like the last letter of the Greek alphabet — Ω ! They number in from the (omega) end until they come to the 1st double bond ! C-18 Fatty Acids Nutritionists are interested in the proportions of the fatty acid types ! COOH COOH 18:1 — Oleic Acid COOH Saturated 18:2 — Linoleic Acid COOH Monounsaturated ! Ω9 Polyunsaturated ! 18:0 — Stearic Acid 18:3 — Linolenic Acid Ω6 Ω3 FST10 ©GMS/GFR 2013 OMEGA numbers & saturation ! FST10 ©GMS/GFR 2013 OMEGA numbers & saturation Nutritionists are interested in the proportions of the fatty acid types ! ! ! Polyunsaturated Monounsaturated Saturated FST10 ©GMS/GFR 2013 FST10 ©GMS/GFR 2013 But we do need to know a little more about Fatty acid stuff — Too advanced for FST10 (Don’t write these down; these are just in case you read something about them like the label below...) ! Chemists locate double bonds from the acid end & use the Greek symbol delta (Δ) ! Some biochemists & nutritionists use lower case “n” instead of Ω; well sort of... ! Things like ALA are different from GLA ! Generally best to keep Ω6: Ω3 ratio at or below 4:1 ! See FST100 and advanced nutrition courses Double Bonds ! ! Even though the number of atoms is the same there can be isomers These isomers are called cis- and transFatty Acid Cis & Trans Isomers H H CC 2HC CH2 CIS FST10 ©GMS/GFR 2013 2HC H H CC CH2 TRANS FST10 ©GMS/GFR 2013 So, where to trans- FAs come from? trans- fat. What’s that? Some fatty acids have carbon-carbon double bonds they are not “saturated” with hydrogen. cis- and trans unsaturations have •different shapes •different chemistries, and are broken down by •different enzymes First: Fats versus Oils ! ! CH3 CH2 CH2 CH2 CH2 ... CH2 C OH trans -unsaturated Naturally-occurring fatty acids are cisFatty acids may have more than one unsaturation (mono-,di-, ... poly) They are all cis-unsaturations Lipids containing highly saturated FAs CH3 ! CH2 ... CH2 C OH H CH2 ! C O C CH2 ... CH2 C H have higher melting points ! O C H are liquids at room temperature - Oils. H CH3 CH2 C cis -unsaturated ! have lower melting points ! O saturated Lipids containing highly unsaturated FAs are solids at room temperature - Fats. A process called “Hydrogenation” adds H2 to double bonds by using...
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This note was uploaded on 12/06/2013 for the course FST 10 taught by Professor Jack during the Fall '08 term at UC Davis.

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