Crayfish, as a new consumer trend, has become one of the most popular freshwater aquatic foods in China, and its processed product output has been increasing year by year. In this study, the effect of multi-frequency power ultrasound (MFPU) pretreatment in various working modes including mono-, dual- and tri-frequency on the enzymatic hydrolysis and Maillard reaction of crayfish was investigated. Additionally, the underlying mechanism was also explored. Results showed that the degree of hydrolysis (DH) of crayfish was 23.89 %, while it increased to 40.78 % after MFPU pretreatment at 20/40 kHz dual-frequency, indicating that MFPU pretreatment significantly (p < 0.05) enhanced the enzymatic hydrolysis of crayfish. The crayfish protein after MFPU pretreatment exhibited a decrease in α-helix and increase in β-fold content, and the occurrence in the unfolding of the protein structure and alteration of tertiary structure. According to scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses, the MFPU pretreatment resulted in the fragmentation of crayfish protein. During the analyses of subsequent Maillard reaction, the composition and quantity of volatiles detected by the electronic nose and GC–MS indicated that MFPU pretreatment enhanced flavor of the Maillard reaction products. In conclusion, MFPU pretreatment is a promising technology for improving the degree of hydrolysis of crayfish protein and enhancing the flavor of Maillard reaction products.

中文翻译：

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小龙虾 （Procambarus clarkii） 的多频功率超声 （MFPU） 预处理：对酶水解过程和随后的美拉德反应的影响


小龙虾作为一种新的消费趋势，已成为我国最受欢迎的淡水水产食品之一，其加工产品产量逐年增加。本研究研究了单频、双频和三频等多种工作模式下多频功率超声 （MFPU） 预处理对小龙虾酶解和美拉德反应的影响。此外，还探讨了潜在的机制。结果表明，在 20/40 kHz 双频 MFPU 预处理后，小龙虾的水解度 （DH） 为 23.89 %，而水解度 （DH） 增加到 40.78 %，表明 MFPU 预处理显著 （p < 0.05） 增强了小龙虾的酶解能力。MFPU 预处理后的小龙虾蛋白表现出 α 螺旋减少和 β 倍含量增加，以及蛋白质结构的展开和三级结构的改变。根据扫描电子显微镜 （SEM） 和原子力显微镜 （AFM） 分析，MFPU 预处理导致小龙虾蛋白碎裂。在后续美拉德反应的分析过程中，电子鼻和 GC-MS 检测到的挥发物组成和数量表明 MFPU 预处理增强了美拉德反应产物的风味。综上所述，MFPU 预处理是一种很有前途的技术，可以提高小龙虾蛋白的水解程度，增强美拉德反应产物的风味。