Abstract:

The study aimed to investigate the cryoprotective effect and mechanism of different polysaccharides on grass
carp myofibrillar protein during frozen storage. Grass carp myofibrillar proteins added with 0.5% β-glucanase konjac
glucomannan (KGM) hydrolysate, 0.5% irradiation degraded KGM and 0.5% dextran, respectively, were stored at −18 ℃ for
0, 10 d and 75 d. Changes in myofibrillar protein concentration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis
(SDS-PAGE) pattern and rheology were measured. Results showed that the concentration and storage modulus (G’) of grass
carp myofibrillar protein added with nothing, β-glucanase KGM hydrolysate, irradiation degraded KGM, dextran T7 and a
commercial antifreeze decreased with frozen storage time, which was in accordance with the changes in SDS-PAGE pattern
during frozen storage. At the same time, the concentration and storage modulus (G’) of grass carp myofibrillar protein
added with different polysaccharides were higher than those of the control. It was demonstrated that the cryoprotection
of β-glucanase KGM hydrolysate, irradiated degraded KGM and dextran on grass carp myofibrillar proteins was
achieved by protecting the alpha helix structure of vice myosin and myosin light chain. The cryoprotection of different
polysaccharides was in the decreasing order: irradiation degraded KGM > dextran T7 > β-glucanase KGM hydrolysate.

Key words: myofibrillar protein, polysaccharide, cryoprotective effect, SDS-PAGE, rheology