The effects of limited enzymatic hydrolysis on the physicochemical and emulsifying properties of a lentil protein isolate

The physicochemical and emulsifying properties of lentil protein isolates (LIN) were investigated as a function of their degree of hydrolysis (DH of 4,9 and 20%) following exposure to trypsin/heat. Specifically, interfacial tension, surface characteristics (charge and hydrophobicity) and intrinsic fluorescence were determined. These parameters were then related to changes in the emulsification activity (EAI) and stability indices (ESI) of unhydrolyzed (u-LPI) and hydrolyzed LPI (h-LPI) in a flaxseed oil-water emulsion. Interfacial tension was found to decrease from similar to 6.5 to similar to 6.1 mN m(-1) for u-LPI and h-LPI (DH 4-20%), respectively. A similar trend was observed for surface hydrophobicity, which declined from similar to 30 to similar to 24 for the u-LP1 and h-LP1 (DH 4-20%), respectively. In contrast, surface charge values were similar for all materials (similar to-37 mV). Intrinsic fluorescence as a function of emission wavelengths (300-400 nm) indicated a slight change in the tertiary conformation of LPI upon hydrolysis, where the magnitude of fluorescence intensity declined relative to that of u-LPI. Changes in physicochemical properties upon hydrolysis had a detrimental effect on EAI and ESI values, which declined from similar to 51 to similar to 47 m(2) g(-1) and similar to 12 to similar to 11 min for u-LPI and h-LPI (DH 4-20%), respectively. (C) 2012 Elsevier Ltd. All rights reserved.