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1 Fats Foods that are mostly fat. 2 Trends Total fat consumption in 2000 was 82.3 lb per capita. Total fat consumption in 2004 was 87.5 lb per Between.

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Presentation on theme: "1 Fats Foods that are mostly fat. 2 Trends Total fat consumption in 2000 was 82.3 lb per capita. Total fat consumption in 2004 was 87.5 lb per Between."— Presentation transcript:

1 1 Fats Foods that are mostly fat

2 2 Trends Total fat consumption in 2000 was 82.3 lb per capita. Total fat consumption in 2004 was 87.5 lb per Between 2000 and 2004, salad, cooking, and other edible oils has increased from 34.8 to 40.8 lb per capita. Butter and margarine consumption has decreased from 12 lb to 9.9 lb per In 2004, soybean oil accounted for 87% of all oil production in the US.

3 3 Sources Animal-beef tallow, butter fat (milk), lard from pigs Vegetable-olives, palm berries and palm kernels, cottonseeds, soybeans, rapeseed (canola oil), corn, sunflower seeds, safflower seeds, coconuts, peanuts, cocoa beans, walnuts, macadamia nuts, rice bran Fish oils-decosahexanoic acid (DHA) and eicosapenanoic acid (EPA) are omega-3

4 4 Processing Crude fat is extracted under pressure, extracted by solvents, or rendered from fat tissue by heating Impurities, color, and odor are removed Fats may be further treated to promote specific qualities through hydrogenation, winterizing, or plasticizing

5 5 Other Processes Winterization-chilling oils to remove crystals Hydrogenation-unsaturated fatty acids are exposed to hydrogen gas in the presence of a catalyst. Double bonds may migrate and change from cis to trans configuration. Interesterification or rearrangement-heating fat with a catalyst rearranges fatty acids on the glycerol molecule making fat more heterogeneous with wider range of melting points. Used to give lard a wider plastic range

6 6 Other Processes Continued Acetylation-acetic acid replaces a fatty acid making a fat with lower melting point and the ability to stay in alpha form. Used as coating agent on raisins, meat, etc Superglycerinated-emulsifier (often glycerol monstearate) added to give a wider range of melting points, more plastic

7 7 Deterioration Hydrolytic rancidity-breaking of chemical bonds with the addition of water. Lipase may cause the breaking of bonds. The release of short chain fatty acids give off flavors and odors Oxidative rancidity-reaction is initiated with the loss of a H from a carbon located next to a double bond. Carbon atom becomes a free radical which is very reactive and combines with oxygen to form a peroxide free radical which pulls H from another carbon and continues the chain reaction. These peroxide free radicals break into smaller volatile compounds which give the odor of rancid fat

8 8 Deterioration Continued Flavor reversion-oxidative deterioriation which involves changes in fat due to ultraviolet or visible light or heat in the presence of oxygen catalyzed by metals. Off flavors develop that may be called fishy, beany, or warmed over. Linolenic acid is especially susceptible to flavor reversion

9 9 Antioxidants Butylated hydroxyanisole (BHA) Butylated hydroxytoluene (BHT) Tertiary butyl hydroquinone (TBHQ) Propyl gallate Natural antioxidants like vitamin E or tocopherols, vitamin A or beta-carotene, or vitamin C Rancidity may also be controlled by cold temperature and the exclusion of light, moisture, and air

10 10 Properties of Fat Solubility-fats are insoluble in water and soluble in organic compounds Appearance-natural pigments, sheen, browning Satiety-sense of fullness Flavor-used for flavor they impart, olive oil, butter, peanut oil, bacon fat Texture-flaky pastries, smooth ice cream, crispy fried foods Shortening power-tenderness in baked products

11 11 Melting point determines whether a fat is liquid, plastic, or solid at room temperature. 1. Food fats are neutral fats and phospholipids. The fatty acid attached to the glycerol molecule gives a fat it’s characteristics. As fats cool, molecules slow down, align and crystallize. The melting point of a fat is a measure of the strength of bonding forces between fatty acid radical and crystals. A higher attraction means less slowing is needed giving a higher melting point.

12 12 Attraction between molecules or melting point depends on 1. Saturation versus Unsaturation CH 3 CH 2 CH 2 COOH CH 3 CH=CHCOOH CH 3 CH 2 CH 2 COOH CH 3 CH=CHCOOH High Low High Low 2. Length of chain Long Saturated Short Saturated Long Saturated Short Saturated Low High Low High 3. Cis or trans configuration Low High Low High 4. Crystalline structure-polymorphism Melting point increases with crystal size Melting point increases with crystal size

13 13 Polymorphism-Variation in Crystalline Form 1. Alpha-small, transparent crystals, seen in frozen desserts and candies 2. Beta prime-delicate needles, seen in shortening 3. Intermediate-3 to 5 microns long 4. Beta-25 to 100 microns long, seen in lard 5. Alpha crystals have low melting point which increases with beta crystals

14 14 Plasticity-fat has two phases 1. Solid-crystals of fat 2. Liquid-oil surrounds crystals 3. Plastic fats allow for the incorporation of air in the mixing or beating process, such as creaming shortening with sugar when making cakes

15 15 Heat Transfer 1. Fat conducts heat well, gives high temperature without boiling, browns foods. 2. Smoke point-temperature fat begins to smoke, decomposition occurs 3. Acrolein-decomposition product which is a derivative of glycerol is irritating to the eyes and mucus membranes

16 16 Choosing a Frying Fat 1. High smoke point 2. Bland flavor, light color 3. Resistance to rancidity 4. Uniformity of quality 5. Stability for long term use 6. Gives excellent taste, texture, and appearance 7. Ease of use-form and packaging

17 17 Care of Fat 1. Use appropriate temperature 2. Adequate turnover 3. Filter fat daily 4. Remove food particles, as they can lower the smoke point and cause darkening with reduces the appearance and flavor of the product

18 18 Fat Absorption 1. High even temperature-less absorption 2. Shorter time-less absorption 3. Increased surface area-more absorption 4. Character and composition of food a. High fat + sugar-increases absorption b. Egg-increases absorption c. Stiffer doughs-decrease absorption d. Softer doughs-increase absorption

19 19 Low-Fat Cooking 1. Use lean, trimmed meats and less meat 2. Use roasting or broiling cooking techniques 3. Reduce the amount of fat used in the recipe, may replace with fruit puree in baking 4. Use non-stick pans 5. Use vegetable oil spray, chicken broth or water to saute foods 6. Use skim milk instead of whole milk or cream 7. Use egg whites 8. Use low-fat cheeses, salad dressings, and table spreads

20 20 Fat Substitutes Fat-Based Replacements Fat-Based Replacements 1. Salatrim-structured triglyceride with long and medium chain fatty acids where breakdown is decreased in the intestine 2. Caprenin-structured triglyceride of capric, caprylic, and behenic acid which are inefficiently absorbed from the intestine 3. Olestra-hybrid fat and CHO substitute. Sucrose polyester-sucrose molecule with 6 to 8 medium chain fatty acids attached. Molecule cannot be digested or absorbed

21 21 Fat Substitutes Continued Protein-Based Replacement Protein-Based Replacement 1. Simplesse-microparticulated egg white and milk protein Carbohydrate-Based Replacements Carbohydrate-Based Replacements 1. Oatrim-maltodextrin and beta-glucan 2. N-oil-hydrolyzed tapioca starch 3. N-lite-starch, gums, and non-fat dried milk 4. Stellar-cornstarch 5. Slendid-pectin base 6. Maltrin-maltodextrin from corn starch 7. Rice*Trim 3 Complete-rice 8. STA-SLIM-potato starch 9. Avicel cellulose gel-a microcrystalling CHO derivative 10. Polydextrose-water soluble fiber

22 22 Emulsions 1. Dispersion of one liquid in another where the two liquids are immiscible 2. Three phases Dispersed phase-suspended droplets Dispersed phase-suspended droplets Continuous phase-solution in which droplets are dispersed Continuous phase-solution in which droplets are dispersed Emulsifier-a substance with affinity for both liquids but it is unequal Emulsifier-a substance with affinity for both liquids but it is unequal a. Prevents coalescence of droplets a. Prevents coalescence of droplets b. Decreases surface tension b. Decreases surface tension

23 23 Types of Emulsions 1. Temporary-lowers surface tension but does not prevent coalescence. Example: Italian dressing or home-made French dressing 2. Semipermanent –stabilizers used to decrease separation. Example: commercial French dressing 3. Permanent-lowers surface tension and prevents coalescence. Example: mayonnaise 4. Emulsifying agent-phospholipids, lecithin, phosphatidyl ethanolamine from gelatin, egg whites, egg yolks, casein, whey, cellulose derivatives, spices, vegetable gums, and starch pastes

24 24 Power Point Author Dr. Jane Ross Dr. Jane Ross The University of Vermont Foods and Nutrition Basic Concepts of Food


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