The effect of various methods of cooking upon the retention of nutrients in vegetables has long been of interest to the food analyst and dietitian alike. The results reported have been so variable, however, that they have been difficult to interpret. Part of the variability has been caused by changing methods of analysis and differences in the methods of cooking, but much has resulted from a failure on the part of many workers to replicate the cookings. The present paper reports data on the ascorbic acid retention in cabbage during cooking by four commonly used methods and shows the importance of replicate cookings. The effect of the various cooking methods upon the color of the vegetable is reported also.
EXPERIMENTAL PROCEDUREVarieties and Source of Cabbage. Five varieties of cabbage were used: Marion Market, Danish Ballhead, Golden Acre, Resistant Detroit, and Bugner. They were grown on University plots under supervision of the Horticulture Division. All of the gatherings were analyzed within a few hours after harvest and a few were analyzed also after 24 hours' storage at 5°C.Preparation and Cooking of Samples. The heads of cabbage from each gathering were matched as nearly as possible according t o size and general appearance and were distributed to form three t o five similar groups. One of the groups was used for preliminary cookings which were made to find the minimum periods necessary to give a tender product by each of the cooking methods. The other groups were used for replicate cookings.The details of preparing the cabbage for cooking and analysis were as follows: all of the heads belonging to a single group were cut into five wedge-shaped pieces. One piece from each head was assigned to the raw sample and one to each of the cooking methods. The samples intended for cooking were wrapped in waxed paper and returned to the refrigerator. The wedges in the raw sample were coarsely shredded, the shredded material well mixed, and aliquots removed for ascorbic acid and moisture determinations. The samples reserved for cooking were withdrawn from the refrigerator, one after the other as quickly as they could be handled. In each case the cabbage was coarsely shredded and mixed, then a 215-gm. and ,a 25-gm. portion were weighed, the latter tied into a loose cheesecloth bag, and both portions cooked together by one of the methods listed below for the length of time decided upon during preliminary cooking tests ( Table I). The vegetable was drained, the contents of the bag emptied immediately into a Waring Blendor containing cold, 3 per cent inetaphosphoric acid, and a portion of the cooking water set in an ice bath t o cool quickly. The procedure of bagging the ascorbic acid samples places that determination directly on the raw weight basis and eliminates the cooling period (and the possibility of oxidation during that time) which is necessary if small cooked portions are t o be weighed with even a moderate degree of accuracy. The other group of heads were removed from the refrigerator one after the other as rap...
