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The effects of immersion freezing and air freezing at different temperatures (-18 and -38 ℃) on the quality of braised beef with potato were studied by physicochemical measurements, microstructural observation and sensory evaluation. The results showed that freezing at -38 ℃ maintained better quality of braised beef with potato compared with freezing at -18 ℃, and immersion freezing was significantly superior to air freezing. The freezing time of beef and potato in the dish under -38 ℃ immersion freezing was shortened by 96.02% and 97.34%, respectively, compared with air freezing at -18 ℃, and the time required to pass through the maximum ice crystal formation zone for beef and potato was 9.67 and 10.92 min, respectively, suggesting improved freezing rate of the dish. Under this condition, the L*, a* and b* values of beef and potato were closer to those of the unfrozen dish; the hardness and elasticity of beef were significantly higher than those of the other frozen treatment groups (P < 0.05), and the shear force was 25.35 N, which was closer to that of the unfrozen sample (26.70 N), indicating good toughness of beef; the hardness of potato was 341.95 g, which was significantly higher than that of (P < 0.05) air-frozen samples, indicating good texture. Scanning electron microscopy (SEM) showed that beef muscle fibers were not broken after immersion freezing at -38 ℃, the gap between muscle fiber bundles was the smallest, arranged in an orderly manner; the cell contour of potato was clear and compact. The overall sensory score of the immersion-frozen sample was higher than that of the air-frozen one, and the sensory scores of beef and potato in the dish after -38 ℃ immersion freezing were 88.80 and 86.80 points, respectively, indicating higher acceptability. These findings provide a theoretical basis for the development of freezing preservation technologies for industrialized Chinese dishes.

To explore the changes in water status and protein characteristics of Tibetan pork (TP) under modified atmosphere packaging (MAP) with different oxygen concentrations compared to Duroc×Landrace×Yorkshire pork (DLY), the water holding capacity (WHC), water distribution, protein oxidation, and conformation of both types were determined. Results indicate that under MAP, TP pork and DLY pork exhibited higher water retention and lower protein oxidation compared to air packaging. However, with increased oxygen concentration in the MAP, protein oxidation intensified, leading to reduced WHC in the pork. Compared to DLY pork, TP pork in different packaging conditions maintained the integrity of protein secondary and tertiary structures, reducing protein cross-linking aggregation. The lower content of P 3 in the two-dimensional relaxation spectra, shorter T 1 and T 2 relaxation times, and higher proton density suggest better water retention properties in Tibetan pork. These findings support the development of long-distance preservation and transportation technologies for TP pork., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)