Diverse rheological properties, mechanical characteristics and microstructures of corn fiber gum/soy protein isolate hydrogels prepared by laccase and heat treatment

Abstract

Two types of corn fiber gums (CFGs) were extracted from corn fibers (CFs) obtained from wet or dry corn milling processing. Both CFGs could form hydrogels induced via laccase, but CFGs isolated from wet milling CFs exhibited higher storage modulus (G′) and better mechanical strength as obtained from rheological testings. Afterwards, CFGs from wet milling CFs and soy protein isolate (SPI) were used to fabricate CFG-SPI double network (DN) hydrogel using laccase and heat treatment processes, in which CFG solution formed the first gel network through laccase oxidation, while SPI formed the second network through heating. When compared with single network (SN) CFG-SPI hydrogel, the DN CFG-SPI hydrogel looked more firm and complete with better elasticity. The rheological testings showed that both the storage modulus (G′) and loss modulus (G″) of DN hydrogel were higher than SN hydrogels of CFGs or SPI. Moreover, the CFG-SPI DN hydrogels exhibited more applicable hardness compared to SPI hydrogels and better deformation ability compared to CFG hydrogels. The results from scanning electron microscopy indicated that these CFG-SPI DN hydrogels had more regular, denser inner structure and smoother surface than SN hydrogels.