LIPIDS - LIPIDS Definition Lipids are the substances in foods that are soluble in organic solvents but not in water This category includes

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LIPIDS Definition Lipids are the substances in foods that are soluble in organic solvents, but not in water. This category includes triglycerides, fatty acids, phospholipids, some pigments, some vitamins and cholesterol. When a lipid is solid at room temperature it is often referred to as a fat and if it is liquid it is called an oil. This difference in melting point results from the lipid's fatty acid structure will be discussed below. Fat Content of Some Foods Oils and shortenings 100% Butter, margarine 80 Most nuts 60 Peanut butter, bacon 50 Cheese, beef roasts 30 - 35 Franks 25 - 30 Lean pork, ice cream 12 - 13 Milk, shellfish 2 - 4 Functions of fat in the body Energy store Muscle fuel Emergency reserve Padding Insulation Cell membranes Raw materials to make vitamins and hormones Historically lipids have been a prized and important source of calories for people. Lipids are designed to be a very efficient way to store calories. In times when food was scarce and many died of starvation the ability to obtain and store calories was vital to survival. When we discussed insulin it was noted that when carbohydrates are limiting insulin is not produced. If there is no insulin glucose cannot enter muscle cells. When glucose is not present muscle metabolizes lipids for energy.
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Lipids also play structural roles in the body. Many vital internal organs are surrounded by a layer of lipid that serves as protection. Lipid can also pad the contact of bony areas with the environment and make sitting, for example, more comfortable. A vital role of lipids is in the structure of cell membranes. Cell membranes are approximately half lipid. Most of this lipid is a special kind called phospholipids. In animal cell membranes cholesterol also plays an important role. Lipids are also used by the body to make a number of important molecules. Some are important to brain development while others are used as messengers in the body. Functions of Fats in Foods Source of essential fatty acids There is one fatty acid that the body cannot make and must have. This makes it an essential nutrient. If there is no fat in the diet, a deficiency of this nutrient could occur. The essential fatty acid is linoleic acid. Adds caloric density Most people in developed countries worry about consumption of excess calories. For most of human history, a lack of calories was a major cause of death. In many less developed countries this is still a problem. Thus, fat and its high nutrient density (9 Kcals/g) plays an important role in adequate nutrition. Most animals and many plants store their excess calories in the form of fat. Because there are more calories per gram for fat than for any other nutrient, more energy can be stored in less space as fat. Carrier for flavors
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This note was uploaded on 06/22/2011 for the course FDSCTE 201 taught by Professor Magino during the Spring '11 term at Ohio State.

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LIPIDS - LIPIDS Definition Lipids are the substances in foods that are soluble in organic solvents but not in water This category includes

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