Effect of lacto-fermented pickled liquids on physicochemical, microbial and sensory quality attributes of grass carp (Ctenopharyngodon Idella) fillets during cold storage

Grass carp, a key aquaculture species in China known for its rapid growth and nutritional value, faces challenges in fillet preservation due to oxidative and microbial degradation during storage. This study evaluated different mixtures of lacto-fermented pickle liquids (LFPLs) (A, B, C, and D; complete formulation in the Methods section) as natural treatments to enhance the physicochemical, microbial, and sensory quality of grass carp fillets under cold storage. LFPL treatments demonstrated strong antioxidant activity, significantly decreasing thiobarbituric acid reactive substances (TBARS) values by 24.35 %, 26.96 %, 46.96 %, and 54.78 % for treatments A, B, C, and D, respectively. Additionally, peroxide values decreased by 44.69 %, 43.60 %, 46.80 %, and 49.79 % for treatments A, B, C, and D. Carbonyl content decreased by 25.37 %, 28.82 %, 36.25 %, and 44.04 %, while the sulfhydryl content for treatments A, B, C, and D increased significantly by 9.26 %, 10.30 %, 16.27 %, and 34.14 %, respectively. Furthermore, LFPLs reduced total volatile basic nitrogen (TVBN) by 47.56 %, 49.94 %, 52.38 %, and 52.66 % for treatments A, B, C, and D, while also preserving organoleptic properties, improving texture, reducing cooking loss, suppressing microbial growth, and maintaining higher whiteness. Principal component analysis revealed that LFPL-treated fillets after 12 days of storage had properties similar to control samples after 6 days. Overall, LFPLs serve as novel preservatives and natural antioxidants, improving the quality and shelf life of grass carp fillets during cold storage.