EFFECT OF PROCESSING ON VITAMINS 5 



showed no effect on A content. Fraps and Treichler (68) found that, when 

 dried in vacuum, carrots lost 80 percent, sweet potatoes 29 percent, and 

 canned spinach 65 percent of their original vitamin A. There is a marked 

 loss of vitamin A in drying cabbage and other vegetables, as reported by Delf 

 and Skelton (38), Steenbock and Gross (204), and Steenbock and Sell (206). 

 A few experiments show some degree of retention of vitamin A in dried 

 foods. Thus, Morgan and Francis (150) and Steenbock and Gross (203) 

 showed that pumpkin, sugar beets, beets, parsnips, and potatoes could be 

 carefully dried so as to retain a substantial part of their original vitamin A. 



Effect of Other Factors on Vitamin A 



When pickled in a salted rice bran paste, Chinese cabbage lost 50 percent 

 of its vitamin A, according to Miller and Robbins (140). Norris (161^ showed 

 that irradiation of cod liver oil for 8 hours destroyed all the vitamin A. 



Summary on Vitamin A 



It would appear that at freezing and low storage temperatures little loss 

 occurs, but at ordinary temperatures there is a gradual loss in carotene and 

 vitamin A in green vegetables. Drying is decidedly harmful in most products, 

 although, unless prolonged, a considerable percentage of the A is retained. 

 Sun-drying is decidedly more injurious than dehydration. Sulfur dioxide 

 treatment of dried fruits aids in conserving the vitamins A and C. In general, 

 rapid cooking and usual home and commercial canning methods do not ma- 

 terially injure vitamin A. It is well recognized that oxidation rather than 

 heat is the destructive factor. Any means of avoiding oxidation and enzyme 

 activity will aid in conserving the vitamin in food preservation processes. 



With the development of rapid, reasonably accurate chemical methods for 

 carotene determination in plant tissues, greater clarification of the effects of 

 environmental factors on vitamin A in fruits and vegetables may be confidently 

 expected in the near future. For excellent summaries of vitamin A investi- 

 gations in the past twenty-five years, reference should be made to the reviews 

 by Karrer and Wehrli (101), McCollum (125), and Harris (82). 



VITAMIN D 



The usual natural sources of vitamin D are milk, butter, eggs, and fish oils. 

 It is not found in abundance in fruits and vegetables, but occasional references 

 to its presence have been noted. Mushrooms contain a small amount of D, 

 according to Scheunert and Reschke (184). Coffin (25) reported small amounts 

 of D in many common foods including vegetables. Weatherby (219) claimed 

 that some D was present in avocados; Morgan (145) found a little in dates; 

 and Cultrera (29) reported D in tomatoes. That vitamin D is present in 

 rhubarb even after cooking is attested by Barshai, Fomin, and Shvatshko (6). 

 Munsell and Kennedy (156) found no D in lettuce. Morgan (146) showed 

 that the sun-drying of prunes, grapes, peaches, and apricots produced no 

 increase in the negligible D content of these fruits In China, Lo (122) found 

 the mottled gram bean to be a fair source of D. 



