Cryoprotective effect of fistular onion stalk polysaccharide on frozen surimi derived from bighead carp: Physicochemical properties and gel quality during storage

The search for cryoprotectants has garnered significant attention due to the susceptibility of myofibrillar proteins (MP) to freezing denaturation during frozen storage, leading to the degradation of surimi quality. In this study, we investigated the effects of fistular onion stalk polysaccharide (FOSP), a byproduct of dry fistular onion leaves, on the physicochemical properties of frozen surimi derived from bighead carp during storage at −20 °C for 150 days. FOSP-3, the primary constituent of FOSP, possesses a molecular weight (MW) greater than 4 kDa and consists of galactose (Gal), arabinose (Ara), glucuronic acid (GlcA), and glucose (Glc) in a molar ratio of 0.71:0.15:0.04:0.10. Our results from texture profile analysis (TPA) reveal that the addition of FOSP (4% and 8%) improves the gel strength, chewiness, and springiness of the surimi gel, with the most significant effect observed at FOSP (4%). Furthermore, the storage modulus G' (Pa) of the surimi/FOSP composite gel surpasses that of the control group (CK), indicating the superior springiness of the composite gel. Moreover, the inclusion of FOSP reduces centrifugal loss, suggesting an enhanced water-holding capacity of the surimi gel. Importantly, the presence of FOSP delays the decline of Ca2+-ATPase activity and the increase of carbonyls, while stabilizing the secondary structure of MP. Therefore, FOSP emerges as a potential cryoprotectant for the frozen surimi industry, offering promising advantages in enhancing the quality and stability of surimi during frozen storage.