Characterization and identification of a fraction from silver carp (Hypophthalmichthys molitrix) muscle hydrolysates with cryoprotective effects on yeast

Abstract

This study was aimed to characterize and identify a fraction from silver carp muscle hydrolysates (SCMHs) with cryoprotective effects on yeast. The SCMHs were obtained from the hydrolysis of silver carp (Hypophthalmichthys molitrix) muscle with Protamex at 50 °C for 15–240 min. The addition of SCMH generated from 30 min of proteolysis (SCMH-30) led to an increase in the yeast survival rate from 0 – 1% (control) to 82–91% after 1–2 freeze-thaw cycles. The SCMH-30 was further separated into two fractions using gel filtration chromatography. The fraction F2 with lower average molecular weight exhibited better cryoprotective effect on yeast, which was further characterized via HPLC-MS/MS. Among a total of 2500 identified peptides, 90% of them had molecular weight between 1000 and 3000 Da, which were mainly derived from parvalbumins. The selected primary peptides were rich in glutamic and aspartic acid residues and exhibited structural and sequential similarities with type IV fish antifreeze proteins, which likely contributed to the high antifreeze activity of F2 from SCMH-30. Results from this study provided an approach for development of effective cryoprotectants using SCMHs and helped to understand the underlying mechanism governing cryoprotective effect of SCMH-30 on yeast.