Sodium tripolyphosphate inhibits the formation of lysinoalanine in heat-treated whey protein

Abstract

Heat treatment is a common method to improve certain functional properties of whey protein, whereas this process is usually accompanied with the formation of lysinoalanine (LAL), which may reduce the protein nutritional value and even cause safety concerns. This study aimed to investigate the effect of the protein content (8–10%, wt/vol), pH (7.5–8.5), heating temperature (70–85 °C), and time (5–20 min) on the degree of LAL generation in thermal treatment of whey protein concentrate (WPC) solutions. Results showed that the LAL content increased significantly (p 10 min) increased respectively. Addition of sodium tripolyphosphate (STPP, ∼0.6%, wt/wt) significantly (p < .05) reduced LAL content by 35.5%. We concluded that STPP can effectively inhibit the LAL formation during thermal treatment of WPC under the alkaline condition (e.g., pH 8.5). Practical applications Whey proteins have been widely used in food industry. It is necessary to investigate the lysinoalanine (LAL) (a cross-linked amino acid) content in heat-treated whey protein products. The LAL formation during thermal treatment of whey protein concentrate solutions at high pH values was inhibited by adding sodium tripolyphosphate (a food additive).