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 degrees 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 degrees 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. (C) 2011 Elsevier Ltd. All rights reserved.