PSIII-1 A preliminary study to investigate the contribution of different tenderness factors to beef loin, tri-tip and heel tenderness

Abstract

The objective of this study was to identify the relative contribution of tenderness factors for 3 beef muscles with similar tenderness ratings. Longissimus lumborum (loin), tensor fascia latae (tri-tip) and gastrocnemius (heel) were collected from 10 USDA choice beef carcasses, fabricated into steaks and assigned to a 5 or 21 d aging period (n=60). Heel had the greatest relative troponin-T degradation %, followed by tri-tip and loin (68.10, 53.42 and 35.01 % respectively; P< 0.01). Tri-tip had the longest sarcomere, followed by heel and loin (3.01, 2.59 and 1.71 µm, respectively; P < 0.01), and heel increased in sarcomere length from 5 to 21 d of postmortem storage (2.49 vs 2.70 µm; P< 0.05). As expected, heel had the greatest collagen content, followed by tri-tip and loin (6.06, 3.98 and 2.76 mg/g of muscle tissue, respectively; P< 0.01), and collagen content decreased for all cuts from 5 to 21 d of postmortem storage (4.64 vs 3.90 mg/g muscle tissue; P< 0.05). Out of the 3 cuts, heel had the highest collagen crosslink density (0.20 mol/mol collagen; P< 0.05), while loin and tri-tip did not differ (0.13 and 0.15 mol/mol collagen, respectively; P >0.05). Collagen crosslink density increased for all cuts from 5 to 21 d of postmortem storage (0.14 vs 0.20; P< 0.01). Heel had lower lipid content than the others (2.68 %; P< 0.01), while tri-tip and loin did not differ in lipid content (8.24 vs. 6.99 %; P >0.05). Loin was ranked by the trained panel to have the highest overall tenderness, while tri-tip and heel did not differ in overall tenderness (P >0.05). The overall tenderness value for heel was positively correlated with troponin-T degradation (P< 0.01). On the other hand, overall tenderness value for loin was negatively correlated with lipid content (P< 0.05), and overall tenderness value for tri-tip was negatively correlated with collagen content (P< 0.05). These results indicated that each beef cut had a unique profile of tenderness contributors.