The fabrication and characterisation of surimi gel modified by konjac glucomannan with the different hydrolysis degree

Abstract

Summary The gel performance of surimi‐based products is indispensable technological attribute responsible for their high popularity. Here, surimi gels with tunable gel properties were successfully fabricated based on the double network theory. Konjac glucomannan (KGM) hydrolysed for various periods (0, 5, 15, 30, 60 and 90 min) was introduced into surimi systems. Corresponding structural characterisations including FTIR, XRD, SDS‐PAGE and grafting degree assessment, were conducted to confirm the presence of double crosslinking reactions. Furthermore, the gel strength, dynamic rheology, thermal stability and in vitro digestibility of the surimi gels were investigated. Red shifts in the amide A band and an increase in relative intensity indicated that hydrogen bonding existed in the complex systems, according to the FTIR spectra. The XRD patterns suggested that the crystalline structures were weakened by interfering with the protein chain arrangement due to the Maillard reaction. In addition, SDS‐PAGE and o‐phthalaldehyde (OPA) assays also confirmed that myofibrillar protein and hydrolysed KGM were partially linked by covalent bonding. The SK‐2 group showed the greatest mechanical strength and lowest digestibility amongst all groups due to its dense hierarchical structure. This work may provide inspiration for the design and development of surimi gels with improved gel properties via microarchitectural modulation.