Effect of Maillard Browning Reaction on Nutritional Quality of Protein

Abstract

The Maillard reaction, or non-enzymatic browning reaction, between reducing sugars and proteins (amino acids), is known to cause serious deterioration of food quality during processing and storage. Increasing evidence shows that these compounds formed under mild conditions substantially reduce the availability of amino acids and proteins. Data obtained by ourselves and others has shown there is a significant decrease in the nutritional value of foods which undergo the Maillard reaction beyond that accounted for in the loss of biologically available lysine. In the present investigation, a mixture of egg albumin and glucose was used as a model system. The nutritional quality of egg albumin as a function of the extent of Maillard browning with periods of less than 10 days of storage was evaluated by in vivo and in vitro methods. A substantial decrease in nutritional quality of protein was observed even at the initial period of storage (less than three days) and most available in vitro methods could not reveal this change. The result of a three-month rat feeding experiment indicated that there were physiological and biochemical changes in rats fed with browned protein diet. It is extremely inportant at the present time to have information on the nutritional value and aspects of food safety of browned food products with respect to nutritional labelling policy. Therefore, in addition to the development of new food products with high protein quality, the practical applications of this study are also discussed.