NUTRIENT RETENTION CALCULATION Comparisons of Methods for Calculating Retentions of Nutrients in Cooked Foods

Six types of weight changes that occur when food is cooked by different methods are described. For five of these types, true retentions of nutrients (defined as calculations based on nutrient content of known weights of food before and after cooking) were compared with apparent retentions (defined as calculations based on nutrient content of moisture-free raw and cooked foods). Comparisons included retentions of proximate components, minerals, and vitamins. Apparent retentions overestimated the true retentions in nearly all instances. To avoid bias, true retentions should be reported whenever it is feasible to obtain data on weights of foods before and after cooking.