The effect of storage and processing on the ascorbic acid content of different varieties of cabbage, peas and potatoes
Warren, Margaret Irene
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In Canada today there is considerable evidence of suboptimal nutrition as shown by dietary surveys carried out in a number of cities across the country. In each study it was found that the ascorbic acid consumed by the family was below the standard requirement, and that it was one of the most extreme deficiencies in a large proportion of the people. There are two distinctly separate dietary standards used in Canada today. To determine the requirement of a nutrient for an individual, a standard was drawn up by the National Research Council of the United States in 1941, and tentatively accepted by the Canadian Council of Nutrition in 1942. This standard allows a wide margin of safety for each nutrient to insure optimum nutrition for everyone. The daily adult allowances suggested are 75 mgm. for men and 70 mgm. for women. Allowances are given also for children of various ages. The second dietary standard was constructed by the Canadian Council of Nutrition in 1945 for the purpose of planning food supplies for a population. The average requirement for a representative group of people was used to construct the standard, and the suggested daily allowances for ascorbic acid are 50 mgm. for adults and 30 mgm. for children. Although the nutritional status of the people of Canada may be below the optimum level, extreme malnutrition is practically unknown. In other parts of the world, however, particularly in Europe and India starvation is prevalent. The shortage of food supplies is extremely grave, and it is imperative that the losses in nutrient value caused by such universal practises as transportation, storage and cooking should be determined and minimized as much as possible. It is also of extreme importance that the food which is produced is of the highest possible nutritional value. Ascorbic acid, or vitamin C is one the most unstable of the vitamins. It is water-soluble and destroyed by oxidation in the air, especially in an alkaline solution. The losses caused by storage, cooking and canning of fruits and vegetables may be so large as to impair the usefulness of these foods as sources of the vitamin in question. Although there are many data on the ascorbic acid content of vegetables grown elsewhere, there is little known concerning the amount in Manitoba vegetables. Therefore it was considered worth while to study Manitoba vegetables along these lines. The three vegetables chosen for this study are cabbage, peas and potatoes, since they are all good sources of ascorbic acid and commonly grown in the province. The purpose of the work is threefold; firstly to determine the ascorbic acid content of several varieties of cabbage, peas and potatoes grown in Manitoba, and to compare these results with those of other workers; secondly, to compare the ascorbic acid content of these vegetables grown at the University of Manitoba with that of vegetables grown in other districts of the province; and thirdly, to determine the effect of maturation, short-term refrigerator storage, long-term root-house storage, cooking, canning and other household practises on the ascorbic acid content of the vegetables.