4 - Effects of storage, cooking and processing on the nutritive value of potatoes

Summary

The nutritional value of the potato was considered in Chapter 2, where brief mention was made of the changes in nutrient content of raw potato that result from the various fates of the tubers after harvesting. Goddard & Matthews (1979) have stressed the need for data on the nutrient content of food in the form in which it is actually consumed so that planners may correctly assess intake of nutrients in order to provide a balanced diet. The purpose of this chapter, therefore, is to review current literature pertaining to the changes taking place in potato nutrient content as a result of storage, cooking or processing.

Not all of these changes are adverse or even very significant. Nutrient losses, however, do occur to a varying extent depending on the operation involved. It should be remembered, however, that post-harvest handling of some kind is often essential; the potato has to be cooked before consumption, and storage and processing are frequently needed to prevent seasonal gluts and to increase the availability of potatoes to consumers throughout the year. Some nutritional losses are therefore inevitable. The major points and extents of loss are given below as guides for workers in the fields of storage, nutrition, dietetics, catering and processing and to indicate possibilities for prevention or reduction of such losses.

Other vegetables also undergo adverse nutritional changes after harvesting. However, the potato's skin acts as a barrier, preventing or reducing leaching of nutrients into the cooking water. The skin itself is a source of some nutrients and may be consumed. In contrast, many other vegetables lack a protective skin and are subject to leaching losses during cooking.