Cryoprotective effects and mechanisms of soybean oligosaccharides on the grass carp (Ctenopharyngodon idellus) surimi during frozen storage

Abstract Background Conventional cryoprotectant mixtures (sucrose and sorbitol) impart excessive sweetness and calories to surimi. Therefore, there is a need to explore alternative cryoprotectants with low sweetness and low‐calorie content. The cryoprotective effects and possible mechanisms of soybean oligosaccharides (SBOS) on the frozen stability of grass carp ( Ctenopharyngodon idellus ) surimi were investigated during 120 days of frozen storage, comparing with commercial cryoprotectants (4% sucrose and 4% sorbitol, w/w). Results 6% ~ 8% (w/w) SBOS and commercial cryoprotectants could restrain water mobility and reduce thawing loss of frozen surimi by increasing non‐freezable water content. SBOS could maintain the structural stability of proteins by preventing sulfhydryl groups from being rapidly oxidized to disulfide bonds, retarding the reduction of the solubility, Ca 2+ ‐ATPase activity and α‐helix content of myofibrillar proteins (MP), and hindering the increasing surface hydrophobicity of MP of surimi during 120‐day frozen storage. The introduction of SBOS increased the gel strength and water‐holding capacity of frozen‐stored surimi. Compared with commercial cryoprotectants, 8% SBOS was more effective in stabilizing protein structure, while slightly less effective in ice‐forming inhibition. Conclusion The results suggested that 8% SBOS could be potentially developed as a new cryoprotectant for surimi due to its abilities of ice‐forming inhibition and protein structure stability. This article is protected by copyright. All rights reserved.