18 MASS. EXPERIMENT STATION BULLETIN 338 



GENERAL SUMMARY 



The effects of storage, freezing, drying, and thermal treatments on the 

 several vitamins are discussed at the end of the respective chapters. A 

 bibliography of 235 references to the literature is appended. 



Generally speaking, ordinary storage and to a lesser extent cold storage in air 

 have no serious effect on vitamins D. E, and G; have a slight to moderate 

 destructive action on vitamins A and B; and cause serious loss of vitamin C, 

 particularly when storage is long continued. Losses are reduced when storage 

 is near the freezing point. Shipped-in vegetables may lose substantial quanti- 

 ties of vitamin C during shipment and incidental marketing operations. This is 

 not true in the case of most fruits and such acid vegetables as tomatoes and 

 rhubarb. Properly packaged frozen fruits and vegetables show practically no 

 losses in any of the vitamins even after long storage at 0° F. or below. 



Destruction of vitamin C is very rapid when frozen fruits and vegetables are 

 defrosted in air. 



Little loss in vitamin C occurs if solidly frozen vegetables are cooked in 

 boiling water without previous defrosting. 



Sun-drying is more destructive to vitamins A and C than artificial de- 

 hydration. 



Fermentation of fruits and vegetables is injurious to vitamin C. 



In general, heat treatments such as cooking and canning are not injurious 

 to any of the vitamins, but the accompanying oxidations and other destructive 

 reactions, unless carefully controlled, are decidedly injurious to vitamins B 

 and C. Fruits or vegetables containing added acid may be heated with less 

 destruction to vitamins B, C, and G than non-acid foods. Thus, canned 

 fiuits retain vitamin C very well, while canned vegetables lose much of their 

 original C. Modern methods of vacuumization and air removal and sealed 

 packaging now used in the food preservation industries are practical aids in 

 preventing vitamin losses through oxidation. It is not believed that cooking 

 and canning are harmful to the vitamins A, G, D, and E of fruits, vegetables 

 and cereals. 



Heat in the presence of alkalies is very destructive to all the vitamins. 



Rapid cooking, with minimum exposure to air, serves to minimize losses of 

 vitamins C, A, and B. 



Food manufacturing operations such as blanching, open-kettle cooking, pulp- 

 ing, and filling containers are ordinarily destructive to vitamin C and probably 

 to a lesser degree to B and A as well. 



There is no satisfactory evidence that foods once canned lose appreciable 

 quantities of any vitamins on storage. Losses of vitamins C and A in reheating 

 canned foods for table use are small. 



Large quantities of the water-soluble vitamins B, C, and G are dissolved 

 in the cooking water of fruits and vegetables and are lost unless this cooking 

 water is utilized. 



