The effect of processing on the nutritive value of flesh foods

Table I shows the nutritional contribution made by flesh foods (i.e.meat, fish, poultry and egg products) to the diet in Britain in 1969 and underlines the importance of these foods in the supply of fat, protein and vitamins A, D and those of the B complex.It will be demonstrated that processing of these foods can cause alterations in protein availability and loss of vitamins, and these aspects represent, therefore, important losses with regard to human nutrition.Table I.Percentage contributions made by Pesh foods to nutrient content of household food consumption (from Ministry of Agriculture, Fisheries and Food, 1969) Vitamin 'As retinol equivalent.The principal problem associated with any evaluation of protein quality is the difficulty in measuring, accurately but meaningfully, the protein damage resulting from a given process.Biological measurements such as biological value (BV), net protein utilization (NPU) and protein efficiency ratio (PER) will reveal changes in nutritional quality only when these changes affect the limiting amino acid.On the other hand, chemical analysis may provide misleading information since the linkages formed in the protein as a result of processing may be resistant to hydrolysis by digestive enzymes in vivo but will be labile to the harsh acid hydrolysis that is included in amino acid analysis.Miller, Hartley & Thomas (1965) showed that amino acid analysis of protein hydrolysates was a poor indicator of the protein quality of heated cod-muscle preparations, as measured biologically with rats and chicks.The microbiological