Cryoprotective Effect of Tara Gum on Myofibrillar Protein from Grass Carp during Frozen Storage

To investigate the cryoprotective effect of tara gum on myofibrillar proteins, the influences of tara gum on the freezing curve of myofibrillar proteins of grass carp were studied using a commercial cryoprotectant (4% sucrose+4% sorbitol) as a control in this study. The effects of tara gum on the freezing stability of myofibrillar proteins during frozen storage (0~28 days) were investigated by assessing Ca²⁺-ATPase activity, sulfhydryl content, surface hydrophobicity, endogenous fluorescence spectra and water mobility. The results showed that the freezing temperature of myofibrillar proteins solution added with 1% tara gum and commercial cryoprotectant were −8.3 ℃ and −7.3 ℃, respectively, which were significantly lower than that of the control (−5.5 ℃). After 28 d of frozen storage, the Ca²⁺-ATPase activity, total sulfhydryl content, and active sulfhydryl content of myofibrillar proteins with the addition of 1% tara gum and commercial cryoprotectant decreased by 45.69% and 45.17%, 24.49% and 42.28%, 25.13% and 39.79%, and the surface hydrophobicity increased by 176.00% and 122.23%, respectively. The changes were significantly lower than those of the blank control. Additionally, the results of LF-NMR showed that the addition of 1% gum and commercial cryoprotectant significantly inhibited the increase of water mobility of myofibrillar protein solution after thawing. Therefore, the 1% tara gum could enhance the stability of myofibrillar proteins of grass carp during frozen storage.