Transglutaminase treatment and pH shifting to manipulate physicochemical properties and formation mechanism of cubic fat substitutes

A cube-shaped pork fat substitute (CFS) was created from soybean protein isolate (SPI), coconut oil, and konjac glucomannan (KGM). The effect of transglutaminase (TG) treatment and pH shifting on the mechanical, thermal, and sensory properties of the cube fat substitute were investigated. The sensory evaluation and oral tribological results showed that the CFS with 1 % TG at pH = 8 was the closest to natural animal fat. The TPA results showed that the hardness, cohesiveness, and chewiness gradually increased with the increasing pH. The DSC results indicated that TG treatment and higher pH levels enhanced the thermal stability of the CFS. FTIR spectroscopy confirmed that when heated in alkaline conditions, KGM deacetylated, and the strength of carbonyl group in acetyl group decreased gradually. The protein network structure was more evident after TG treatment as observed via CLSM, where the KGM molecular chains were entwined as the pH increased, forming continuous, gel networks.