Coating preservation has a remarkable effect on the preservation of aquatic products. This work prepared a composite coating using konjac glucomannan (KGM) as the film-forming matrix and ε-polylysine hydrochloride (ε-PL) and ferulic acid (FA) as the preservative. Three types of treated sea bass (KGM, KGM-ε-PL, and KGM-ε-PL-FA) and untreated sea bass were stored at 4 °C for 20 days to compare freshness changes under different treatment conditions. The results showed that the surface color and texture of sea bass in refrigerated storage changed dramatically and deteriorated as storage time increased. The composite coating treatment was significantly different from the control group. Using Gas-phase ion migration spectrometry (GC-IMS) technology, 32 volatile compounds, such as aldehydes, alcohols, and ketones, were found in fillets during flavor quality analysis. The composite coating can successfully inhibit the formation of odor compounds such as 2-nonenone, isoamyl alcohol monomer, ammonia, and trimethylamine, delaying the deterioration of fish and improving freshness. Among them, KGM-ε-PL-FA composite coating has the most remarkable preservation performance, which significantly inhibits the occurrence of rotten odor, and has a potential application prospect in the field of food preservation.

Soy protein isolate (SPI) possesses potential gelling properties, making it suitable for gel-based applications. However, the gel network stability and mechanical properties of SPI are relatively poor and can be improved through modifications or by combining it with other polymers, such as Konjac Glucomannan (KGM). Combining SPI with KGM can overcome the poor gel network stability and mechanical properties of SPI, but it reduces the water-absorbing capacity of the gel network after drying, which affects the quality characteristics of plant-based protein rehydrated foods and limits the economic feasibility of soy protein foods. In this study, SPI and KGM are the main research objects. By using the alkali method to construct SPI/KGM dry gels with good gel properties, the influence of different ultrasonic powers on the rehydration kinetics and performance changes of SPI/KGM dry gels is examined. The speed and state of water entering the pores are simulated by constructing different pore-size capillary filling models, and the rehydration mechanism of the gel is elucidated. This study provides research ideas and a theoretical basis for the application of ultrasonic wave technology in the study of dry product rehydration performance.