Effect of enzyme hydrolysis on the functionality, protein quality, and flavour profile of lentil and chickpea protein isolates

The overarching goal of this research was to investigate the effect of trypsin hydrolysis on the functional properties, protein quality, and flavour of chickpea and lentil protein isolates (CPI and LPI, respectively) at varying levels of hydrolysis (5%, 10%, 15%, and 20%). The protein content remained in the range of ~ 69-74% and ~ 80-83%, and lipid was increased from 2.1% to 0.5% to ~ 17% and ~ 2% for CPI and LPI, respectively. The surface charge and hydrophobicity were generally enhanced while changes to surface and interfacial tension varied greatly. The solubility of CPI and LPI increased by 10 and 30 times, respectively. The oil holding capacity also improved from ~ 1 to ~ 1.5–2.6 g/g. Most hydrolysates maintained emulsion stability at pH 7.8, whereas decreases were observed at pH 4.5. Modifications to water holding capacity and foaming properties varied between pulses with CPI having reductions in the attributes while those for LPI were generally positive. However, the LPI protein quality decreased (from 55 to 32%), while it improved for CPI (from 55 to 60%), with the limiting amino acid for both being tryptophan. Flavour compounds including aldehydes, alcohols and ketones were present before and post hydrolysis. Based on the findings, the present pulse hydrolysates could be applied into liquid-based formulations and processed meats for their enhanced solubility and fat retention, while LPI and CPI could also find use as a foaming agent or to improve amino acid nutrition, respectively.