Food waste and loss of weight in cooking.

There is a dearth of information on the percentage of waste during preparation of food by the average woman. Such figures would be of value in dietary surveys, since some food tables give analyses for raw foods only 'as purchased', so that edible portions on dietary records must often be converted to 'as purchased' amounts before conversion to calories and nutrients. During two long-term dietary investigations, records of wastage in food preparation were made and results are presented for comparison with existing tables or as a supplement to them. In addition, alterations in weight during cooking are of great importance when the nutritive value of edible portions of food is to be calculated. Alterations are chiefly due to loss or absorption of water or other liquid and also to loss of weight when fat melts and connective tissue hydrolyses to gelatin. Outer layers of old potato may slough away and fish may break apart.