High pressure processing of whole soymilk: Effect on allergenicity, anti-nutritional factor, lipoxygenase activity and E-nose-aroma characteristics

Abstract

Soymilk was subjected to high pressure processing (HPP) at different pressure levels (300–600 MPa) and time (5, 15 and 25 min) intervals. After the HPP treatment, a mild reduction was observed in soymilk pH and conductivity values; however, a sudden surge in the protein content (17.34±0.10 mg/ml) was recorded at 600 MPa (5 min) treatment. When soymilk proteins were evaluated for their structural changes, FTIR (amide regions), CD spectra, and UV inflorescence showed the positive responses and as the result, soy Kunitz trypsin inhibitor (SKTI) antigen binding ability reduced from 100% to 44.39±8.50% at 300 MPa (5 min). However, prolong exposure at 300 MPa had a negative effect on allergenicity. Nevertheless, HPP treatment reduced the lipoxygenase (100.00% to 68.13±12.80%) and trypsin inhibitor (100.00% to 91.30±1.45%) activities. In addition, the treatment also slightly altered the viscosity, whiteness, and volatile aroma components of soymilk after HPP treatment. Principal component analysis revealed that among 22 selected volatiles, only those belong to PC1 and PC2 caused 68% variance in aroma changes. Overall, HPP treatment reduced allergenicity, trypsin inhibitor activity and lipoxygenase activity without modifying the soymilk nature. Further, it also reduced the beany flavor inducing hexanal volatile content after the treatment.