Frozen storage is a prevalent technique for maintaining the freshness of fish. However, fish quality is susceptible to decline throughout the freezing period, substantially impacting its flavor and nutritive content. Hence, this article examines the mechanisms behind the quality degradation and the control strategies employed to preserve fish during frozen storage. Firstly, the formation of ice crystals and the reasons for the decline of fish meat quality were clarified. Secondly, the factors that may lead to quality deterioration during frozen storage were analyzed, including protein denaturation, fat oxidation and enzymatic reaction. Furthermore, the novel freezing control technologies for the deterioration of fish frozen storage quality were reviewed, including the technology of adjusting the nucleation, growth behavior, and recrystallization of ice crystals, and the technology of improving the freezing rate. Finally, the development direction of the research on the deterioration of frozen fish quality in the future was prospected, and novel technologies and methods to improve the quality of frozen fish were pointed out, which is expected to lay a foundation for higher quality frozen fish meat in the future.

The unripe palmleaf raspberry, namely Fupenzi (FPZ), is an important medicinal and edible food. This study aims to evaluate the potential of FPZ extracts prepared with different approaches in attenuating hyperglycemia, gout, Alzheimer's disease, and pigmentation, to obtain the enriching fraction and to identify the major active compounds. Results indicated that FPZ extracts showed weak activity against acetylcholinesterase, considerable ability against tyrosinase and xanthine oxidase, but excellent inhibition on α-glucosidase. Ultrasound-assisted 40 % ethanol extract (40EUS) gave the highest phenolics content, and the best α-glucosidase inhibition (IC₅₀ = 0.08 μg/mL), which is 877-fold higher than that of positive control acarbose. The 40 % ethanol eluting fraction of 40EUS showed the strongest a-glucosidase inhibition with the IC₅₀ value of 37.79 ng/mL, it could also effectively attenuate the fasting blood glucose level and oral glucose tolerance of C57BL/6 mice. Twenty-six compounds were identified from 40 % ethanol fraction by using HPLC-QTOF-MS/MS, hydrolysable tannins (including 11 ellagitannins and 4 gallotannins) were the major compounds, phenolic acids came to the second. Above results could provide important technical supporting for the further application and research of FPZ in health foods and drugs against diabetes.