Abstract: The objective of the present study was to investigate the mechanism underlying the changes in beef tenderness and water-holding capacity during stewing by examining cooking loss rate, Warner-Bratzler shear force, myofibril fragmentation index (MFI), sarcomere length and low field nuclear magnetic resonance (LF-NMR) characteristics. Results showed that cooking loss percentage increased significantly with increasing heating temperature (P < 0.05). Warner-Bratzler shear force overall increased with increasing temperature despite a decrease from 45 to 55℃ and from 75 to 95 ℃. Meanwhile, MFI significantly increased as temperature rose from 55 to 65 ℃ (P < 0.05), which may be ascribed to the liberation of actin from actomyosin, which also contributed to the decreased tenderness at 55 ℃. LF-NMR analysis indicated that both transverse relaxation time (T21) and peak area (A21) decreased significantly. Sarcomere length and cooking loss percentage also decreased significantly with increasing temperature from 55 to 65 ℃. These results demonstrated that controlling the temperature in the range of 55–65 ℃ is critical during beef stewing, which could provide a theoretical basis for processing Chinese braised beef at low temperature.

Key words: beef, stewing, water, protein, tenderness