Loss of available lysine during processing of different dulce de leche formulations

Dulce de leche is a dairy-based confectionery product prepared by heat concentration of milk and sugar, which can be partially replaced by other sugars. The effect of different formulations commonly used in the manufacture of this product on the rate of available lysine loss by Maillard reactions was examined. The replacement of 10% of sucrose by glucose increased by 90% the rate of lysine glycation, while the rise with fructose was only 30%. The use of skim milk led to a low fat product with the same available lysine content as the traditional one. Dulce de leche prepared with lactose-hydrolysed milk had a very low available lysine value.