Fats

1. Fats • Foods that are mostly fat 1

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. 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

11. Melting point determines whether a fat is liquid, plastic, or solid at room temperature. • 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. 11

12. Attraction between molecules or melting point depends on • Saturation versus Unsaturation • CH3CH2CH2COOH CH3CH=CHCOOH • High Low • Length of chain • Long Saturated Short Saturated • Low High • Cis or trans configuration • Low High • Crystalline structure-polymorphism • Melting point increases with crystal size 12

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

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

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

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

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

18. Fat Absorption • High even temperature-less absorption • Shorter time-less absorption • Increased surface area-more absorption • Character and composition of food • High fat + sugar-increases absorption • Egg-increases absorption • Stiffer doughs-decrease absorption • Softer doughs-increase absorption 18

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

20. Fat Substitutes • Fat-Based Replacements • Salatrim-structured triglyceride with long and medium chain fatty acids where breakdown is decreased in the intestine • Caprenin-structured triglyceride of capric, caprylic, and behenic acid which are inefficiently absorbed from the intestine • 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 20

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

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

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

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