Changes in Quality and Collagen Properties of Cattle Rumen Smooth Muscle Subjected to Repeated Freeze—Thaw Cycles

This study revealed changes in the quality, structural and functional collagen properties of cattle rumen smooth muscle (CSM) during F-T cycles. The results showed that thawing loss, pressing loss, β-galactosidase, β-glucuronidase activity, β-sheet content, emulsifying activity index (EAI), emulsion stability index (ESI), surface hydrophobicity, and turbidity of samples were significantly (p < 0.05) increased by 108.12%, 78.33%, 66.57%, 76.60%, 118.63%, 119.57%, 57.37%, 99.14%, and 82.35%, respectively, with increasing F-T cycles. Meanwhile, the shear force, pH, collagen content, α-helix content, thermal denaturation temperature (T(max)), and enthalpy value were significantly (p < 0.05) decreased by 30.88%, 3.19%, 33.23%, 35.92%, 10.34% and 46.51%, respectively. Scanning electron microscopy (SEM) and SDS-PAGE results indicated that F-T cycles induced an increase in disruption of CSM muscle microstructure and degradation of collagen. Thus, repeated F-T cycles promoted collagen degradation and structural disorder in CSM, while reducing the quality of CSM, but improving the functional collagen properties of CSM. These findings provide new data support for the development, processing, and quality control of CSM.