CHAPTER 4: LIPIDS (FAT AND OILS)
LIPID is a group of fatty substances including triglycerides & cholesterol, that are soluble in fat, not water, and that provide a rich source of energy and structure to cell.
FAT is a lipid that is solid at room temperature.
OIL is a lipid that is usually liquid at room temperature.
TRIGLYCERIDE is the major form of lipid in food and in the body; it is made of three fatty acids attached to a glycerol backbone.
FUNCTIONS OF LIPIDS:
Fat accounts for 13-30 % or more of a person’s weight.
Essential of part of cell membranes
Many of fat cell is located under the skin, where fat provides insulation for the body and a cushion around critical organ.
Optimum body temperature in cold weather
Provide much of energy in our body which is 9kcal and spares protein from being burned as energy.
Transport the fat-soluble vitamins (A, D, E, and K) throughout the body.
Essential fatty acids are needed for normal growth and development in infants and children. It used to maintain structural part of cell membranes and functioning of immune system.
In foods, fat enhance taste, flavor, aroma, crispness, juiciness, tenderness and texture. Fats have satiety value.
Ø A triglyceride is made of three fatty acids attached to glycerol.
Ø Fatty acids can be saturated, monounsaturated, or polyunsaturated.
Ø All food contains a mixture of saturated and unsaturated fats.
I. Fatty acids are a major component of most lipids. Three fatty acids are present triglyceride.
II. Glycerol is a derivative of carbohydrate that is part of triglycerides.
III. Point of unsaturation is the location of the double bond in unsaturated fatty acids.
IV. Saturated fat is a triglyceride made of mostly saturated fatty acids.
V. Monounsaturated fat is a triglyceride made of mostly monounsaturated fatty acids.
VI. Polyunsaturated fat is a triglyceride made of mostly polyunsaturated fatty acids.
VII. Saturated fatty acid is a fatty acid that is filled to capacity with hydrogens.
VIII. Unsaturated fatty acid is a fatty acid with at least one double bond.
IX. Monounsaturated fatty acid is a fatty acid that contains only one double bond in the chain.
X. Polyunsaturated fatty acid is a fatty acid that contains two or more double bonds in the chain.
Trans fats (trans fatty acids) is unsaturated fatty acids that lose a natural bend or kink so that they become straight after being hydrogenated; they act like saturated fats in the body.
Hydrogenation is a process in which liquid vegetable oils are converted into solid fats (eg: margarine) by the use of heat, hydrogen, and certain metal catalysts.
ESSENTIAL FATTY ACIDS: OMEGA-3 AND OMEGA-6 FATTY ACIDS
Alpha-linolenic acid is an omega-3 fatty acid found in several oils, notably canola, flaxseed, soybean, walnut, and wheat germ oils. It is vital to growth and development, maintenance of cell membranes, and the immune system and inadequate in many Americans’ diets.
Linoleic acid is an omega-6 fatty acid found in vegetable oils such as corn, safflower, soybean, cottonseed, and sunflower oils. It is vital to growth and development, maintenance of cell membranes, and the immune system.
Cholesterol is the most abundant sterol. A soft, waxy substance present only in foods of animal origin. It is present in every cell in your body.
The body used cholesterol to:
i. Make bile acids, which allow us to digest fat
ii. Maintain cell membranes
iii. Make many hormones
iv. Make vitamin D
Bile acids is a component of bile that acids in the digestion of fats in the duodenum of the small intestine.
Reference: Drummond, K. E. & Brefere, L. M. (2010). Nutrition for foodservice and culinary professionals. New Jersey: John Wiley & Sons Inc.