Development and mechanical properties of soy protein isolate-chitin nanofibers complex gel: The role of high-pressure homogenization

Abstract

To enrich the use of soy protein isolate (SPI) gel as texture assistance, we introduced nanofiber into gel system. Firstly, a stable positively charged chitin nanofibers (CNFs) suspension was fabricated by a high-pressure homogenization approach, showing a diameter from 20 nm to 100 nm and ζ-potential from 41.0 mV to 12.7 mV (pH from 3.0 to 8.0). The rheological property of CNF suspensions was concentration-dependent and showing G' > G″ at all test concentration. Subsequently, the gelation kinetics and mechanical properties of SPI-CNFs complex gels were investigated by phase diagram, scanning electron microscopy, rheological and textural analyses. The rheological results showed that the gelation time, gelation concentration and gel strength of SPI-CNFs complex gel (1%–9%) were much shorter, lower and stronger than that of the SPI gel (1%–9%), respectively. Meanwhile, the final stress value of SPI-CNFs complex gel during compression test was about 2-fold compared with SPI gel. We inferred that the CNFs provided an initial framework for gel formation and introduced rigidity to the SPI gel. Thanks to the electrostatic interactions, the surplus SPI molecules was to fill in the CNFs structure as gelation component. The study can provide information on the potential use of complex gel as meat analogs.