Meat Science and Muscle Biology : Fresh Meat Quality and Muscle Biology

Intramuscular collagen contributes to the variation in background toughness of meat. Vitamin E may reduce intramuscular collagen maturity, while vitamin C has been reported to improve meat texture in beef. The objective of this study was to investigate whether vitamins E and C are able to regulate collagen turnover in bovine intramuscular fibroblasts, the cells responsible for its synthesis and degradation by secretion of matrix metalloproteinases (MMPs). Fibroblasts were isolated from longissimus dorsi (LD) and semitendinosus (ST) muscles from a yearling animal and grown in DMEM + 10% FCS. Fibroblasts were treated with vitamins E and C for 24 h as follows: 1) with 50 or 100 μM of vitamin E, 2) 50 μM of vitamin C, 3) either 50 μM vitamin E+50 μM vitamin C, or 100 μM vitamin E+50 μM vitamin C. Control cells received no vitamins. After treatment for 24 h, media were collected and analyzed for MMP-2 activity by zymography. Cell lysates were tested for total collagen synthesis (TC) using the Sircol assay. Data were analyzed by 2-way ANOVA, Fisher’s LSD and Pearson bivariate correlation. Vitamins E and C each increased (P < 0.05) the activity of MMP-2 secreted by fibroblasts from both muscles, but the effect was stronger (P < 0.05) in cells derived from LD than from ST. A synergistic effect between vitamins E and C on MMP-2 activity was observed for cells from both muscles. Both vitamins increased TC in cells from both muscles above the controls to a different extent; higher TC values (P < 0.05) were found for ST cells versus LD cells. There was a strong positive correlation (P < 0.05) between MMP-2 activity and TC synthesis. These results confirm the hypothesis that both vitamins may increase collagen turnover in intramuscular fibroblasts, which could have direct implications for the response of these muscles to the animal’s diet, affecting collagen turnover in vivo. A high rate of collagen turnover may lead to increased collagen solubility in muscles which can affect meat tenderness.