The quality of fresh Pseudosciaena crocea cultured in four different aquaculture modes, namely, raft cages, through-frame cages, deep-water net cages and deep-sea seine, and those cultured in deep-sea seine and stored under one of the two typical distribution conditions of chilling and freezing was comprehensively evaluated by measuring body size parameters, springiness, crude fat content, surface color (yellowness/blueness, b*), sensory evaluation score and total volatile basic nitrogen (TVB-N) content, and their quality grading was performed according to the standard Rules for the Evaluation of High Quality Cultured Pseudosciaena crocea (T/CROAKER001-2018). The results showed that seine net cultured Pseudosciaena crocea had a higher rate of superior quality, which was close to that of wild Pseudosciaena crocea; during the circulation process, the quality of Pseudosciaena crocea from the ice platform (IP) group, thawing ice platform (TIP) group and frozen storage (FS) group gradually deteriorated, among which the TIP group had the fastest rate of quality deterioration. On the second day of storage, its freshness failed to reach the standard for superior quality, and its b* value fell to below 25 at 14 h. The quality of Pseudosciaena crocea from the FS group was judged to be superior on the 30^th day of frozen storage, and on the 180^th day, the springiness, TVB-N content and sensory score were close to the unacceptable end point. The overall quality evaluation showed that the superiority rate of deep-sea seine cultured Pseudosciaena crocea was 62.5%, while the quality of Pseudosciaena crocea from the IP and TIP groups could not be judged to be superior at the 3^rd and 2^nd day of storage, respectively, and the quality of Pseudosciaena crocea from the FS group could not be judged to be superior after 30 days of freezing. The results of this study can provide a reference for the quality control of cultured Pseudosciaena crocea during farming and postmortem storage.

The microbial community diversity in huangjiu (yellow rice wine) vinasse during spontaneous fermentation into Xiangzao was analyzed by high-throughput sequencing. It turned out that the bacterial and fungal diversity was abundant. During the whole fermentation process, Proteobacteria was the dominant bacterial phylum, whose relative abundance ranged from 71.26% to 75.27%. The relative abundance of Firmicutes was 16.09% in the initial stage of fermentation and showed a downward trend in the middle and late stages. The dominant bacterial genera were Aquabacterium and Brevundimonas. The relative abundance of Aquabacterium was 22.48% at the beginning of fermentation, increased to 24.94% at the middle, and decreased to 21.29% at the end. Bacillus and Lactobacillus were also found during fermentation. The dominant phylum of fungi was Ascomycota, and its relative abundance decreased from 63.46% at the beginning of fermentation to 51.68% at the end. The dominant genus of fungi was Pichia, and its relative abundance ranged from 6.58% to 13.79%. Additionally, the relative abundance of Tausonia and Mortierella was above 3%. To sum up, the microbial community diversity is abundant during the spontaneous fermentation of huangjiu vinasse, and the fermentation process has a significant impact on the relative abundance of microorganisms.

To improve the gel properties of squid surimi products, we optimized the addition of modified corn starch acetylated distarch phosphate (ADSP) and the non-muscle proteins egg white protein (EWP) and soy protein isolate (SPI), and we evaluated the effects of the addition of ADSP, EWP and SPI on the texture, intermolecular force, protein secondary structure and microstructure of squid surimi products. Furthermore, we explored the mechanism by which modified starch and non-muscle protein improve the gel quality of squid surimi products. The results showed that the gel properties of squid surimi products with 10% ADSP, 7% EWP and 6% SPI were the best. Compared with the control group, the addition of modified starch or non-muscle protein decrease the relative contents of random coil and α-helix in proteins, and increased the contents of β-sheet and β-turn. Their combined addition was beneficial for the retention of β-sheet and β-turn structures during the gelation process, and promoted the hydrophobic interaction between proteins, resulting in the formation of a denser gel network structure, which in turn improved the gel strength and water holding capacity of squid surimi products. Correlation analysis showed that the gel strength and water holding capacity, hydrophobic interaction, and relative contents of β-turn and immobilized water of squid surimi products were significantly positively correlated with each other (P < 0.01), and significantly negatively correlated with the contents of free water and random coil (P < 0.01). Therefore, the addition of 10% ADSP, 7% EWP and 6% SPI improved the gel quality of squid surimi products by affecting protein secondary structure and water distribution.

In order to understand the microbial community composition and the evolution of volatile flavor substances during the fermentation process of grass carp with rice wine less and to explore the possibility of using rice wine mash instead of rice wine lees for the fermentation of grass carp, high-throughput sequencing technology was used for sequencing and phylogenetic analysis of the bacterial and fungal communities in unfermented grass carp and three groups of air-dried fermented grass carp (made with lees fermented for 5 days, lees fermented for 2 days and mash fermented for 2 days, respectively), and gas chromatography-ion mobility spectrometry (GC-IMS) was used to analyze their volatile flavor substances. The results showed that the contents of moisture, alcohol and amino acid nitrogen increased with fermentation time, and the pH decreased. The mash fermentation group had the best performance in smell, color, taste and texture, with good overall acceptability. The dominant bacterial genera were Weissella, Citrobacter and Aeromonas in the early stage of fermentation. In the middle and late stages, the abundance of Pediococcus and Lactococcu increased, while the abundance of Citrobacter and Aeromonas decreased significantly. For all three fermented samples, the dominant fungal genus Pichia had an absolute advantage during the fermentation process. A total of 37 volatile flavor substances were detected in all samples, among which acetic acid ethyl ester, ethyl propanoate and 2-butanone, 3-hydroxy were the characteristic flavor substances of fermented grass carp with lees. Weissella, Lactococcu, Pichia and Saccharomyces cerevisiae had a significantly positive correlation with the production of various aroma substances. This study provides the basis for the screening of dominant strains and the optimization of the fermentation process of fermented grass carp.

Changes in the total viable count (TVC), total volatile base nitrogen (TVB-N) content, thiobarbituric acid (TBA) value, K value, water distribution, microstructure and protein degradation of whole, gutted and filleted turbot were determined during ice storage, and the taste profiles were collected using an electronic tongue. Meanwhile, the volatile substances were detected by gas chromatography-ion mobility spectrometry (GC-IMS). The results showed that the filleted fish had higher values of TVC, TVB-N and TBA than the whole and gutted fish during ice storage, with a TVC value of 7.05 (lg (CFU/g)) being recorded after 12 days, exceeding that at the end of storage. In addition, the content of salt-soluble protein in the fillet decreased to the lowest level of 1.57% on day 19, which was accompanied by a greater degree of muscle fiber breakage and increased space between muscle fibers. Compared with the whole fish, the gutted fish had higher TVC and TVB-N values of 6.58 (lg (CFU/g)) and 16.72 mg/100 g on day 19, respectively. The percentages of free water in the whole and gutted fish at the end of storage were 0.21% and 0.28%, respectively, which were significantly lower than that of the fillet (P < 0.05), indicating better maintenance of muscle tissue structure in the whole and gutted fish. Finally, orthogonal partial least squares-discriminant analysis (OPLS-DA) and clustered heatmap analysis based on the measured GC-IMS fingerprints distinguished the whole, gutted and filleted fish at different storage times. In conclusion, the rate of quality deterioration of the fillet was the fastest, followed by the gutted fish, and the quality of the whole fish deteriorated at the slowest rate under ice storage conditions. The results of this study can provide a reference for developing an alternative to traditional live circulation of turbot.

To investigate the effects of different moisture contents on the storability of lightly salted large yellow croaker at 4 ℃, changes in total volatile basic nitrogen (TVB-N) content, microbial community composition, taste and volatile organic compounds were analyzed during the storage period, and the correlation between microbial community composition and VOCs was examined. The results showed that the shelf-life of lightly salted large yellow croaker with moisture contents of 60%, 55%, and 50% was 27, 33, and 39 days, respectively. During storage, there were significant changes in the bacterial flora, with four specific spoilage organisms (SSOs) being dominant at the end of the shelf-life. In the samples with 60% moisture content, Hafnia alvei (61.22%) and Brochothrix thermosphacta (19.39%) were dominant. In the samples with 55% moisture content, H. alvei (31.13%), B. thermosphacta (29.25%), Carnobacterium divergens (17.92%) and Citrobacter freundii (16.98%) were dominant. C. freundii was not observed at the end of the shelf-life of lightly salted large yellow croaker with 50% moisture content, and H. alvei (43.96%) and B. thermosphacta (37.36%) were dominant, respectively. The electronic tongue results showed that the trend of response values was basically the same among the three groups of samples. A total of 29 VOCs were detected by gas chromatography-ion mobility spectrometry (GC-IMS), including seven alcohols, six esters, four ketones, four aldehydes, three amines, two heterocycles, one olefin, one ether and one terpene. The fingerprinting results showed no significant difference in the composition of VOCs among the groups. Pearson’s correlation analysis showed that H. alvei and B. thermosphacta were positively correlated with amines for all groups.