Effect of enzyme hydrolysis on the physicochemical, functional, and nutritional properties of pea and faba bean protein isolates

This research examined the physicochemical, functional, and nutritional aspects of pea (PPI) and faba bean protein isolates (FBPI) modified using trypsin at varying levels of hydrolysis. Enzyme hydrolysis decreased the protein content for both pulse protein isolates and increased the lipid content for pea. The surface charge became more negative, and the surface hydrophobicity was enhanced. The surface and interfacial tension, in general, decreased upon hydrolysis. The oil holding capacity for both pulses increased while the water holding capacity decreased. The foaming capacity of FBPI was significantly lowered by hydrolysis, while in the case of PPI, it increased at pH 4.5 and was unaffected at 7.0. The foaming stability increased for both pulses at pH 4.5 but was reduced at pH 7.0. At pH 4.5, hydrolysis enhanced the emulsion activity index of FBPI, while it decreased the index of PPI. The indices increased for both pulses at pH 7.0. The emulsion stability index was generally reduced for FBPI but improved for PPI after hydrolysis. All samples were limiting in tryptophan and the sulfur-containing amino acids, and in vitro protein digestibility decreased after hydrolysis for both pulses. As the results of these changes, overall protein quality improved for FBPI but not PPI. The degree of protein hydrolysis was an important factor in determining the functional and nutritional attributes of modified pulse proteins along with pH and pulse type.