NSD 115 Lecture 2: Food Science Notes con.

8 Pages
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Department
Nutrition Science & Dietetics
Course Code
NSD 115
Professor
C.Charles

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Food Science Notes 2 Hydrogenation o In order to protect fats from becoming rancid and to increase the shelf-life of foods containing fats, food manufacturers use a process know as hydrogenation o Hydrogenation—a process in which hydrogen atoms are added to the carbon-carbon double bonds of unsaturated fatty acids, making them more saturated o Trans Fatty Acids -- During the process of hydrogenation, trans fatty acids are created Good Sources of Fats -- Tree nuts, Avocados, Coconut oil, Walnut oil, Flaxseeds and flaxseed oils, Grass-fed beef and dairy, Wild-caught fish Phospholipids o Can mix in both water and fat o Present in small amounts in food and in the body o Lecithin is the most common phospholipid o Lecithin is made in the liver, therefore it’s nonessential o Lecithin is a major constituent of cell membranes o Lecithin in foods is used as an emulsifier Sterols In plants o Plant sterols o Help form the cell membrane of plants In animals o Cholesterol (found in animal products) o Made in the liver, therefore it is nonessential o Used to make: o Cell membranes o Myelin sheaths o Vitamin D o Bile acids o Cortisol, testosterone, estrogen Dietary Cholesterol Sources – animal products Lipid digestion, absorption and Transport Lipid Digestion o Fats are hydrophobic (afraid of water so don’t mix with water) o Digestive enzymes are hydrophilic (mix well with water) Goal of fat digestion o Dismantle (take apart) triglycerides o Monoglycerides, fatty acids, and glycerol backbone Digestion of Fat in the Stomach o Gastric lipase o Activated by an acidic environment o Acts on triglycerides containing short- and medium-chain fatty acids Digestion of Fat in the Small Intestine o Primary site of fat digestion o Bile acid released -- Emulsifies digested fat o Pancreatic lipase – enzyme used to break down fats o Fat is broken down o To monoglycerides and fatty acids Absorption of Fat o 95% of dietary fat is absorbed o Diffused into the absorptive cells o Short- and medium-chain (<12 C) fatty acids o Are water soluble o Enter the portal system o Long-chain fatty acids re-form into triglycerides o Not water soluble o Enter the lymphatic system Carrying Fat in the Bloodstream o Water (blood) and oil (fat) are incompatible o Unique system of fat transportation is needed -- Lipoproteins There are four types of lipoproteins o Chylomicrons o Very-low-density lipoproteins o Low-density lipopr
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