Gel properties of grass carp myofibrillar protein modified by low-frequency magnetic field during two-stage water bath heating

The effects of low-frequency magnetic field (LF-MF) on the gel properties of grass carp myofibrillar proteins (GCMPs) and the underlying mechanisms were investigated to explore a better processing method for surimi gel products. GCMPs were untreated or treated with LF-MF of 9.5 mT in the first stage (40 degrees C heating for 50 min) or the second stage (85 degrees C heating for 40 min) of two-stage water bath heating. Results indicated that in the first stage, LF-MF induction may be detrimental to GCMPs unfolding and possibly resulted in a poor and unstable the GCMPs gels network structure, which had a negative effect on gel strength. Hence, water easily leaked from the GCMPs gel, leading to a decrease in WHC. Inversely, the unfolding of a-helix and the formation of random coil of LF-MF treatment in the second stage resulted in more exposure of internal groups, leading to the reduction of ionic bonds and increase of hydrogen bonds. These changed bonds further affected the T-21 relaxation time, increased in PT2b and decreased in PT22, and mainly impacted the bind between water and protein, thus resulting in the improved gel strength and WHC.