Controlled Conversion of Proteins into High-Molecular-Weight Peptides without Additives with High-Temperature Water and Fast Heating Rates

Reaction of bovine serum albumin (BSA) protein in high-temperature (200−260 °C) water (HTW) with fast heating rates (ca. 135−180 K·s–1) without acid or base additives gives high-molecular-weight (1500–8300 Da) peptides with minimal formation of amino acids and ammonia. The decrease in the number-average molecular weight of peptides after HTW treatment of BSA could be described by a kinetic model based on random scission mechanism of the polymer chain. Reaction of BSA in HTW under identical conditions with slow heating rates (ca. 0.25 K·s–1) gives peptides of low molecular weight with formation of amino acids and ammonia for which the kinetics could not be described by a random scission mechanism. The activation energy determined for the conversion of BSA into high-molecular-weight peptides with fast heating rates in high-temperature water was 16.4 kJ·mol–1. Reaction of proteins in high-temperature water with fast heating rates inhibits initial aggregation that occurs during slow heating rates and allows controlled conversion of the denatured polymer chain into high-molecular-weight peptides.