At the end of the shelf life of crayfish stored at 4 ℃, the dominant spoilage organisms in crayfish from Xiaogan, Wuhan were isolated and identified by high-throughput sequencing, and the changes in the bacterial community structure and diversity in crayfish during storage were analyzed. The results showed that 10 spoilage bacterial strains were obtained by the traditional culture-dependent method, including Shewanella baltica, Aeromonas veronii and Proteus vulgaris, etc. Aeromonas sp. and Shewanella sp. were confirmed as the dominant spoilage organisms, with the largest relative abundance at the end of crayfish spoilage. At the same time, the results of high-throughput sequencing showed that the abundance, diversity and evenness of the microbial community decreased with storage time, which was related to the rapid growth of the dominant spoilage organisms and the inhibition of other kinds of microorganisms at the end of the spoilage stage.

This study was carried out in order to explore the effect of high intensity ultrasound on the structural and functional characteristics of Litopenaeus vannamei proteins. After being ultrasonicated for 0, 5, 15, 25 or 35 min at 300 W power, 20 kHz frequency and 382 W/cm² power intensity, the change in the content of tropomyosin was evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked immunosorbent assay (ELISA). It was found that ultrasonic treatment could effectively reduce the allergenicity of shrimp proteins. Fourier transform infrared (FTIR) spectra showed that the secondary structure of the proteins was transformed from random coil to β-turn and β-fold after ultrasonic treatments, and the content of sulfhydryl groups increased, contributing to the formation of a stable three-dimensional network structure. Moreover, the average particle size significantly decreased, and the total antioxidant capacity, free amino acid content and in vitro digestibility of the proteins significantly increased. In conclusion, high-intensity ultrasonic treatment can not only reduce the allergenicity of shrimp proteins, but also change their structure and functional characteristics, and improve their potential nutritional value. This study provides a reference for non-thermal processing and deep processing of Litopenaeus vannamei.