内容: This study systematically investigated lipid metabolic alterations during the dry-curing processing of Wuchang fish (Megalobrama amblycephala) using ultra-performance liquid chromatography-tandem mass spectrometry coupled with an in-house lipidomics database. A total of 1 370 lipid species were identified, classified into six major categories (fatty acids, glycerolipids (GL), glycerophospholipids (GP), prenol lipids, sphingolipids, and sterol lipids) and 41 subclasses. Orthogonal partial least squares-discriminant analysis revealed significant lipidomic divergence among three processing stages (fresh fish (CK), curing for 2 days (Y2), and drying for 2 days (G2)), with GL dominating the lipid profile and GP exhibiting marked depletion during salting. The lipid oxidation index elucidated competing effects of lipid hydrolysis (substrate depletion) and oxidation (metabolite generation), revealing that lipoxygenase-driven conversion of polyunsaturated fatty acids (PUFAs) to volatile aldehydes and alcohols predominated during salting, while reduced water activity in air-drying triggered PUFAs autoxidation and oxylipins accumulation. Post-processing nutritional enhancement was evident, with essential fatty acids (eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, and oleic acid) significantly enriched in air-dried fish, constituting 18.869% of total free fatty acids, a substantial increase from 13.414% in fresh samples. This work provides critical insights into flavor formation mechanisms and quality control strategies for traditional dry-cured fish products.

内容: Protein denaturation induced by ice crystal formation is the main contributor to the deterioration of fish quality during frozen storage. This study aims to extract hydrolysates capable of inhibiting protein denaturation from sea cucumber ovum protein using three types of proteases (pepsin, trypsin, and neutral protease). The enzymatic hydrolysates of sea cucumber ovum protein are capable of stabilizing protein structures through interactions and preventing protein unfolding and aggregation caused by various factors; thus, they are potential protectors against protein denaturation. This study investigated the effectiveness of various enzymatic hydrolysates of sea cucumber ovum protein in mitigating the quality deterioration and oxidative reactions of mackerel under freeze-thaw cycles. The results show that an enzymatic hydrolysates of sea cucumber ovum, identified as sea cucumber ovum protein neutral protease hydrolysate, efficiently maintained the textural properties and oxidative and conformational stability of mackerel fillets during frozen storage. In addition, sea cucumber ovum protein neutral protease hydrolysate inhibited water migration and microstructural damage to myofibrillar proteins during the freeze-thaw cycles, thereby maintaining overall fish quality. The results of this study indicate that sea cucumber ovum protein neutral protease hydrolysate is a promising candidate for sea cucumber ovum use in marine-based food preservation technologies.