218 VITAMINS 



greater vitamin E activity than the others; it is the form usually meant 

 when the term vitamin E is used. Alpha-tocopherol has the structure 

 represented by the following formula: 



CH3 



HO-C^ "C^^^CH, CH3 CH3 CH3 



CH3— C^ ^C>, /C- (CH2) 3— CH- (CH,) 3— CH (CH2) 3-CH— CHj 



I CH3 



CH3 



a-Tocopherol, C29H60O2 



The E vitamins are remarkably stable to heat, alkali, and many ordinary 

 chemical reagents, but they are unstable to ultraviolet light and oxidizing 

 agents. The potency of food materials containing these vitamins is 

 rapidly destroyed by oxidation in the presence of certain fats (notably 

 lard) and iron salts. The E vitamins are also destroyed in rancid fats. 



Occurrence 



The amounts of alpha-tocopherol and of all the various tocopherols 

 present in some common food materials are listed in Table 9-2. Certain 



Table 9-2 



Tocopherol (vitamin E) content of foods 



Tocopherol content * 



Food Total Alpha 



Bread, white 0-23 



Butter 2.40 



Cheese, American 1-00 



Chocolate, unsweetened 11-1 5.3 



Corn oil 87 7' 



Cottonseed oil 90 56 



Eggs, hen's 2.00 1.16 



Fruits, various 0.24-0.74 0.23-0.72 



Lard 2.7 2.3 



Margarine 54 28 



Meat, fish, and poultry, various 0.25-1.40 0.21-1.40 



Milk, cow's, whole 0.12 



Oatmeal 2.10 1.94 



Peanuts 9.30 4.60 



Rice, brown 2.40 1.20 



Rice, polished 0.57 0.35 



Soybean oil 140 10 



Vegetables, various 0.06-4.0 0.1^.0 



Wheat, whole 2.20 



Wheat germ oil 200-300 130-195 



Yeast, brewer's, dried 



* Milligrams per 100 g. 



