Question | Answer |
Lipids are insoluble in water but soluble in | fat solvents like hexane and ether |
Food scientists are interested in | triglycerides, phospholipids, sterols like cholesterol |
Importance of lipids | contributes to consistency, chemical reactive leading to off-flavors, provides calories and essential fatty acids, excess leads to heart disease |
Oils | are fats above the melting pt |
Fats | are oils below melting pt |
Sources of fats and oils are from | animals and vegetable |
triclyderides | composed of glycerol and 3 fatty acids |
Fatty Acids | CH_3_-CH_2_-CH_2_----------CH_2_-COOH |
Bonds in carbon atoms | can be single or double |
Single C-C | the fatty acid is saturated |
Single C=C | the fatty acid is monounsaturated |
Double C=C | the fatty acid is Diunsaturated |
Three or more C=C | the fatty acid is polyunsaturated |
Increase in double bonds | equals lower melting pt |
Decrease in double bonds | equals high melting pt |
the rate of oxidation depends on the degree of unsturation | poly > di > mono > unsaturated |
Oxidation is increased by | oxygen, light, heat, trace metals |
All fats go rancid unless it is | highly saturated |
To prevent oxidation we can | remove oxygen, use low temp, package, add chelators like edta, add antioxidants |
Antioxidants commonly used | BHA (butylated hydroxy anisole), BHT (butylated hydroxy toluene), tocopherol vitamin E, vitamin C |
Animal fats | are extracted from adipose tissue by rendering (heating up fats to remove liquid oils which later crystallized into solid fat) |
Vegetable oils | are extracted by crushing oil seeds. Oil seeds are filtered off and then refined. |
Hydrogenation | liquid oils are hardened and turned into plastic fats (margarine and shortenings) |
Process of hydrogenation | oil + hydrogen gas heated with a metal catalyst |