In this study, fresh fish vermicelli was made from surimi and starch using a cutting process. The effects of ultrasonic pretreatment at different powers (120, 150, 180, 240 and 300 W) for different periods (5, 10, 15, 20 and 25 min) on the cooking quality, sensory quality and texture characteristics of fresh fish vermicelli were explored. The underlying mechanism was clarified by measuring the particle size and viscosity of the paste as well as the infrared spectrum, moisture distribution and microstructure of the vermicelli. The results showed that with the increase in ultrasonic power and time, the particle size and viscosity of the paste initially decreased and then increased, while the opposite trend was observed for the percentage of bound water (A₂₁). Decreased ultrasonic time and power improved the dispersion and uniformity of raw materials, increased the water-binding capacity, and promoted fish vermicelli to form a uniform and dense microstructure. Increased ultrasonic time and power caused protein degradation, reduced the microstructural uniformity of fresh fish vermicelli, and deteriorated its quality. Ultrasonic treatment at 120 W for 10 min increased the tensile strength and stretching distance of fresh fish vermicelli increased by 23.98% and 21.08%, respectively, and decreased the broken rate and grout vomiting value decreased by 28.27% and 11.54%, respectively, compared with the control group without ultrasonic treatment. Under this ultrasonic condition, fish vermicelli had the highest sensory score.

The objective of study was to investigate the softening effect and mechanism of Garcinia gummi-gutta on grass carp bones. The pattern of change in the hardness of grass carp bones was studied during pickling using a G. gummi-gutta juice-based marinade at different temperatures (5, 10, 25, and 40 ℃). At the same time, changes in the composition and structure of grass carp bones and in the acidity and pH of the marinade were also determined. The results showed that the hardness of grass carp bones gradually decreased with pickling time, which decreased by 71.5%–79.4% after 25 days of pickling (P < 0.05). The ash content decreased by 11.90%–16.65% (P < 0.05), and the moisture content by 4.23%–13.08% (P < 0.05). The dense and ordered microstructure became loose and porous. This was because the reaction of H⁺ with hydroxyapatite in fish bones enabled calcium to be dissolved from fish bones and the consumption of H⁺ in the pickling solution decreased its acidity and increased its pH. Malic acid was played a major role in softening fish bones. Infrared spectroscopic analysis showed that the triple helix structure of fish bone collagen was not destroyed, but the absorption peak corresponding to amide A shifted to a higher wavenumber, suggesting a reduction in the number of hydrogen bonds, which might be related to the loss of hydroxyapatite in fish bones.