EFFECT OF PROCESSING ON VITAMINS 15 



conditions the actual effect of the various manufacturing operations on the C 

 content of the food product. The new chemical method makes such studies 

 now relatively simple. 



It can be generally assumed that oxidation rather than heat is responsible 

 for losses in vitamin C during the heat treatment of foods. Many experiments 

 of different investigators bear out this statement. 



Woods (224), and Richardson, Douglass, and Mayfield (173) found no 

 appreciable loss in baking or boiling potatoes. Results obtained by Thiessen 

 (208) indicated that potatoes boiled at 199° F. for 15 to 18 minutes showed 

 no vitamin C loss. Scheunert (182) found a maximum of 50 percent loss of 

 C in boiling potatoes and as high as 90 to 95 percent loss in cabbage. Scheunert 

 and Wagner (185) demonstrated that potatoes and cabbage were injured less 

 by boiling than by cooking in a pressure cooker. The reverse was true of 

 spinach. According to Yarusova (229) fried potatoes contained only one-half 

 as much vitamin C as boiled potatoes. Von Hahn (77) found that cabbage 

 after cooking retained only 12 to 15 percent of its original vitamin C; cooked 

 horseradish retained 25 percent; and cooked spinach was practically devoid 

 of C Vinokurov, Eidelman, and Butom (216) found that from 40 to 70 

 percent of the vitamin C in cabbage passed into the juice on cooking for 30 

 minutes. Long-continued cooking caused heavy losses in vitamin C. Tressler 

 and Mack (212) reported very little loss in vitamin C as a result of cooking 

 snap beans, peas, or spinach, though considerable of the vitamin passed into 

 the cooking water. 



Fresh carrots were cooked without injury to C, but stored carrots showed 

 some loss according to Langley, Richardson, and 'Andes (117). Under the 

 same conditions the carrots showed decided loss in vitamin C after canning. 

 Hoff (90) showed that canning destroyed 66 percent and cooking 90 percent 

 of the C in spinach. Wasson (218) found that 10 grams of canned spinach 

 did not protect guinea pigs from scurvy, whereas fresh, raw spinach had a 

 daily protective level of 1 to 2 grams. While 10 grams of fresh carrots were 

 protective, 20 grams of canned or cooked carrots were required for protection 

 from scurvy. Remy (172) described experiments showing that canning is at 

 least partly destructive to the C of green beans, spinach, apricots, peas, and 

 strawberries. Barshai, Fomin, and Shvatshko (6) showed that the C in 

 rhubarb stems was not lost in cooking. However, Clague, Fellers, and Stepat 

 (21) found a 30 to 40 percent loss during the process of rhubarb sauce manu- 

 facture. They, as well as Hessler and Williams (88), found that canned rhubarb 

 contained much less C than fresh. Newton (160) showed that when turnip 

 greens were boiled for 45 minutes, they retained 14 percent of their C; when 

 boiled for 2 hours, only 6 percent of the C remained. A steam blanch was 

 slightly less destructive to vitamin C than a hot-water blanch. When collards 

 were boiled for 2 hours, 25 percent of the C was lost. This laboratory found 

 that commercial canning destroyed from 50 to 85 percent of the C in peas 

 (62, 63), lima beans, spinach, and green asparagus (64). Whole grain sweet 

 corn was one of the vegetables whose C content was least affected by canning 

 (42). On the other hand, Fellers and Isham (56), MacLeod and Booher (123), 

 and also Eddy, Gurin, and Kohman (46) showed that canning had no effect 



