Lactose-amino acid interactions in rations.

Abstract

Heating of lactose-containing diets was shown to reduce markedly their nutritive value to growing rats; the growth inhibition caused by the inclusion of 5% lactose could be overcome by lysine supplementation. This indicated that the Maillard reaction, involving a reaction between lactose and the epsilon amino group of lysine, was occurring. A model system, using the growing rat fed autoclaved diets, was used to evaluate various feed additives for their potential significance in inducing or inhibiting the Maillard reaction. Alfalfa was found to increase strongly the severity of the Maillard reaction. Ethanol extraction removed some of the active fraction; alfalfa ash and alfalfa saponin were both very potent stimulators of the Maillard reaction. The level and type of added fat was also found to influence the response to lactose in the diet. Ammonium sulphate (1 %) reduced the severity of browning, while urea (1%), copper sulphate (250 ppm), zinc sulphate (100 ppm) and calcium carbonate (4%) had no effect. Glutamic acid (1%), glutamine (0.5%), sodium bicarbonate (5%), sodium propionate (1%) and sodium bisulphite (100 ppm) increased the browning effect.