1. Food Chemistry Chapter 17 in Green / Damjii F.2: FATS AND OILS

2. Read F2 – Fats and Oils - pp. 476-477 Do Q 7-11 on p 491 Homework

3. F.2: Fats and Oils F.2.1: Describe the difference in structure between saturated and unsaturated (mono- and poly-unsaturated) fatty acids Remember… 3 molecules of fatty acids react with 1 molecules of glycerol to form a lipid

4. F.2: Fats and Oils F.2.2: Predict the degree of crystallization (solidification) and melting point of fats and oils from their structure, and explain the relevance of this property in the home and in industry.

5. F.2: Fats and Oils Melting point and hardness (degree of crystallization) depend on – Length of hydrocarbon chain Longer chain = greater molar mass = more vdW forces = higher mp – Degree of unsaturation More double bonds = crooked chains = less contact = fewer vdW forces = lower mp – Cis or trans conformation more cis = more crooked chains = less contact = fewer vdW forces = lower mp more trans = less crooked chains = more contact = more vdW forces (compared to cis) = higher mp

6. Triglycerides SATURATED (no double or triple bonds) – Tend to be SOLIDS at room temperature – Tend to come from animal products – “Fat” – Examples: Coconut oil Butter lard

7. Triglycerides Unsaturated (has one double or triple bond) – Tend to be LIQUIDS at room temperature – Tend to come from plant material – “Oil” – Examples Olive oil Canola oil Peanut oil Polyunsaturated (has multiple double or triple bonds) – Example Sunflower oil Corn oil Fish oil

8. F.2: Fats and Oils F.2.3: Deduce the stability of fats and oils from their structure. Unsaturated – More reactive, less stable – C=C double bond reacts with oxygen (auto- oxidation) Especially in sunlight (photo-oxidation) Margarine gets discolored – Hydrogenation – Degradation by microbes

9. F.2: Fats and Oils F.2.4: Describe the process of hydrogenation of unsaturated fats. Hydrogenation Addition of hydrogen – Hydrogen @ high pressure – Temp ~ 200 C – Nickel catalyst

10. F.2: Fats and Oils F.2.5: Discuss the advantage and disadvantages of hydrogenating fats and oils. A hydrogenated product is –more saturated… or fully saturated… –semi-solid or solid… Advantages of a hydrogenated product is – Form is more convenient for some cooking techniques – More stable (rate of oxidation is decreased) – Texture can be controlled ( hardness / plasticity) can be controlled

11. F.2: Fats and Oils Disadvantages: …. health related Mono- and poly-unsaturated are healthier for the heart than saturated fat. Partial hydrogenation can form trans-fats – trans-fats don’t occur naturally – difficult to metabolize – accumulate in fatty tissues of body – Increase levels of LDL chloesterol (associated with atherosclerosis… strokes… heart problems)

12. What is this? Olestra – a fat substitute that is not digested by the body Copyright © 1997 by Daniel J. Berger. http://images.google.com/imgres?imgurl=http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2005/castle/olestra.jpg&imgrefurl=http://www.bio.davidson.edu/people/midorcas/anim alphysiology/websites/2005/castle/page2.htm&usg=__Cs_ytB4MhyvgZs-tnVxiYR1rCrM=&h=360&w=341&sz=16&hl=en&start=11&um=1&itbs=1&tbnid=24- OiiaHITJTsM:&tbnh=121&tbnw=115&prev=/images%3Fq%3Dunsaturated%2Bfat%2B(ester)%26um%3D1%26hl%3Den%26safe%3Dactive%26rlz%3D1R2RNTN_enUS347%26tbs%3Disch:1