Nutrition-Chapter 5

solids/liquids

At room temperature, saturated fats (such as those commonly found in butter and other animal fats) are solid, whereas unsaturated fats (such as those found in vegetable oils) are usually liquid.

hydrogenation

a chemical process by which hydrogens are added to monounsaturated or polyunsaturated fatty acids to reduce the number of double bonds, making the fats more saturated (solid) and more resistant to oxidation (protecting against rancidity). Hydrogenation produces trans-fatty acids.

phospholipid

a compound similar to a triglyceride but having a phosphate and choline (or another nitrogen-containing compound) in place of one of the fatty acids.

lipids

a family of compounds that includes triglycerides, phospholipids, and sterols. Lipids are characterized by their insolubility in water. (Lipids also include the fat-soluble vitamins, described in Chapter 11.)

saturated fatty acid:

a fatty acid carrying the maximum possible number of hydrogen atoms—for example, stearic acid. A saturated fat is composed of triglycerides in which most of the fatty acids are saturated.

polyunsaturated fatty acid:

a fatty acid that lacks four or more hydrogen atoms and has two or more double bonds between carbons; abbreviated PUFA. Examples include linoleic acid (two double bonds) and linolenic acid (three double bonds). A polyunsaturated fat is composed of triglycerides in which most of the fatty acids are polyunsaturated. •

unsaturated fatty acid:

a fatty acid that lacks hydrogen atoms and has at least one double bond between carbons (includes monounsaturated and polyunsaturated fatty acids). An unsaturated fat is composed of triglycerides in which most of the fatty acids are unsaturated.

monounsaturated fatty acid:

a fatty acid that lacks two hydrogen atoms and has one double bond between carbons; abbreviated MUFA. Examples include palmitoleic acid and oleic acid. A monounsaturated fat is composed of triglycerides in which most of the fatty acids are monounsaturated. •

choline

a nitrogen-containing compound found in foods and made in the body from the amino acid methionine. Choline is part of the phospholipid lecithin and the neurotransmitter acetylcholine.

emulsifier

a substance with both water-soluble and fat-soluble portions that promote the mixing of oils and fats in watery solutions.

atherosclerosis

a type of artery disease characterized by plaques (accumulations of lipid-containing material) on the inner walls of the arteries.

plaque

an accumulation of fatty deposits, smooth muscle cells, and fibrous connective tissue that develops in the artery walls in atherosclerosis; also known as atheromatous (ATH-er-OH-ma-tus) plaque.

antioxidants

as a food additive, preservatives that delay or prevent rancidity of fats in foods and other damage to food caused by oxygen.

sterols

compounds containing a four-ring carbon structure with side chains attached.

lipases

enzymes that hydrolyze lipids. Lingual lipase is a fat-digesting enzyme secreted from the salivary gland at the base of the tongue; gastric lipase is a fat-digesting enzyme secreted from the cells of the stomach.

trans-fatty acids

fatty acids with hydrogens on opposite sides of the double bond.

oils

lipids that are liquid at room temperature

fats

lipids that are solid at room temperature

monoglycerides

molecules of glycerol with one fatty acid attached. A molecule of glycerol with two fatty acids attached is a diglyceride. • •

firmness

most polyunsaturated vegetable oils are liquid at room temperature, and the more saturated animal fats are solid. Some oils—notably, cocoa butter, palm oil, palm kernel oil, and coconut oil—are saturated; they are firmer than most vegetable oils because of their saturation, but softer than most animal fats because of their shorter carbon chains (8 to 14 carbons long)

lecithin

one of the phospholipids. Lecithin acts as an emulsifier to combine water-soluble and fat-soluble ingredients that do not ordinarily mix, such as water and oil.

cholesterol

one of the sterols containing a four-ring carbon structure with a carbon side chain.

conjugated linoleic acids

several fatty acids that have the same chemical formula as linoleic acid (18 carbons, two double bonds) but with different configurations (the double bonds occur on adjacent carbons).

point of unsaturation:

the double bond of a fatty acid, where hydrogen atoms can easily be added to the structure.

oxidation

the process of a substance combining with oxygen; oxidation reactions involve the loss of electrons.

hydrophobic

water-fearing, or non-water-soluble, substances; also known as lipophilic (fat loving).

hydrophilic

water-loving, or water-soluble, substances.