Dry heat stress stability evaluation of casein peptide mixture

During food processing, peptide-containing products often experience thermal stress, which can be voluntary heat treatments to prolong expiration date, or unwanted side-effects, e.g. local heating during powder compaction or milling. No information is currently available on the primary structure stability of peptides when heated in the dry state. Therefore, the short-term dry heat stress stability of casein hydrolysate was evaluated by exposure to temperatures of 100, 140 and 180 °C during 1, 3 and 5 min time intervals. Moreover, the impact of oxidising and reducing agents, as well as photolytic stability were assessed. Contrary to the general belief that peptides are heat-labile, based on degradation results in solution, all peptides remained stable up to 3 min at 180 °C. The influence of a reducing environment was found to be minimal, while the impact of an oxidising environment was significant. Our findings open perspectives for thermal peptide processing techniques.