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Response surface methodology optimization based on central composite design was applied to extract flavonoids from the exocarp of three coconut genera. The antioxidant and antimicrobial activities and structures of the flavonoids were determined. The results indicated that the optimal extraction conditions were ethanol concentration, 60%; temperature, 50 ℃; time, 90 min; liquid/material ratio, 40 mL/g; ultrasonic power, 150 W. Under these conditions, the yields of green, red and yellow coconut exocarp were 366.03 ± 7.57, 596.38 ± 10.32, and 403.78 ± 5.56 mg rutin/g powder, respectively. The flavonoids exhibited eminent DPPH and ABTS radical scavenging activities with IC

The present study sought to analyze the lipid profiles of oyster Crassostrea gigas from Yellow Sea (YS), East China Sea, and South China Sea (SCS) through the untargeted lipidomics strategy based on UPLC-Q-Exactive Orbitrap mass spectrometry and multivariate statistics. The results elucidated that geographical differences had profound effects on the lipid content, composition, and lipid molecular profiles. Notably, oysters from the YS group contained the highest lipid content, including triacylglycerol, diacylglycerols, and the majority of phospholipid molecule species, while oysters from the ECS group contained most of the phosphatidylcholine species and the SCS group contained most of the sphingolipid species. Totally, 1155 lipid molecular species belonging to 21 subclasses were identified; of them, 45 lipid molecular species could serve as differential marker for lipid of oysters from different sea areas. Overall, lipidomics could be a potential approach for discrimination of lipid characters between marine shellfishes for geographical origin traceability.

The quality changes in tilapia belly muscle (BM), dorsal muscle (DM) and tail muscle (TM) were studied and the hypothesis of browning of the fillets was revealed during partial freezing. Compared with DM and TM groups, BM samples had higher thiobarbituric acid reactive substances (TBARS) (0.41 mg malondialdehyde eq/kg at 49 d) and K values (61.81% at 42 d) (P 0.05). The microstructure of the BM group deteriorated most obviously during storage. Therefore, the BM group was considered to be the fastest to oxidize and deteriorate. In addition, 54 different micromolecular metabolites were identified from tilapia fillets by UHPLC-Q-TOF-MS analysis, and there were significant differences in the micromolecular metabolites in the three parts of tilapia. Therefore, proteins and lipids were degraded by the action of enzymes and microorganisms to produce some amines and small molecular acids, leading to the deterioration of the quality of tilapia fillets.

The molecular species of glycerophosphocholine (GPCho), glycerophosphoethanolamine (GPEtn), glycerophosphoserine (GPSer), lysoglycerophosphocholine (LGPCho) and lysoglycerophosphoethanolamine (LGPEtn) from six species of edible clams were characterized by using high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. At least 435, 453, 468, 443, 427 and 444 glycerophospholipid (GP) molecular species were characterized, respectively, from Cyclina sinensis, Mactra chinensis Philippi, Mactra veneriformis Reeve, Meretrix meretrix, Ruditapes philippinarum and Saxidomus purpurata. Most of the predominant GP molecular species in clam contained polyunsaturated fatty acids (PUFA), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), indicating that clam is a potential resource of GP enriched PUFA. According to the amount of the major molecular species containing EPA and DHA, Cyclina sinensis was the best fit species for GPCho, Mactra veneriformis Reeve was the best fit species for GPEtn, Mactra chinensis Philippi was the best fit species for GPSer and LGPEtn, and Saxidomus purpurata was the best fit species for LGPCho.

This study was carried out to identify the glycerophosphocholine (GPCho), glycerophosphoethanolamine (GPEtn) and glycerophosphoserine (GPSer) compositions in lipids extracted from mussels using Folch, Bligh-Dyer and methyl-tert-butyl ether (MTBE) methods by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). The molecular species of GPCho, GPEtn and GPSer were characterized according to the MS and MS/MS information. A semi-quantitative method using internal standard was established to compare the difference in glycerophospholipids (GP) between samples recovered with different methods. At least 212, 230 and 206 GP species were identified, respectively, from lipids recovered by Folch, Bligh-Dyer and MTBE methods. Most of the abundant GP species in mussels contained EPA and DHA. Some GP species with low content were not present in lipids recovered by the Folch and MTBE methods when compared with that recovered by the Bligh-Dyer method. However, for most GP species in lipids recovered by different methods, no quantitative differences existed.

Autolysis of sea cucumber, caused by endogenous enzymes, leads to postharvest quality deterioration of sea cucumber. However, the effects of endogenous proteinases on structures of collagen fibres, the major biologically relevant substrates in the body wall of sea cucumber, are less clear. Collagen fibres were prepared from the dermis of sea cucumber (Stichopus japonicus), and the structural consequences of degradation of the collagen fibres caused by endogenous cysteine proteinases (ECP) from Stichopus japonicus were examined. Scanning electron microscopic images showed that ECP caused partial disaggregation of collagen fibres into collagen fibrils by disrupting interfibrillar proteoglycan bridges. Differential scanning calorimetry and Fourier transform infrared analysis revealed increased structural disorder of fibrillar collagen caused by ECP. SDS-PAGE and chemical analysis indicated that ECP can liberate glycosaminoglycan, hydroxyproline and collagen fragments from collagen fibres. Thus ECP can cause disintegration of collagen fibres by degrading interfibrillar proteoglycan bridges.