Influence of Electrical Stimulation and Conditioning Periods Upon Hot-Boned Cooked Beef Semitendinosus Roast ¹

Forty-eight beef sides from 24- to 36-month-old Holstein and various crosses were used to evaluate the influence of electrical stimulation and conditioning periods upon physical changes, shear force, panel tenderness scores, palatability traits and cooking yield of prerigor and postrigor semitendinosus (ST) muscle roast. The intact ST muscle was excised from the left sides [20] within 30 min postexsanguination and electrically (ES) stimulated (50 v; 5 ms on; 70 ms off; 3 min), while the remaining paired muscles [20] served as controls (NS). In addition, the left side from four carcasses was ES and the right side served as the control (NS). These eight sides were aged for 7 d before removal of the ST muscle. After stimulation, the [40] muscles were placed in a L600 Cryovac® bag and assigned to the following conditioning periods: 0, 1, 2, 3 h and 7 d. The remaining ST muscles [8] were removed from the sides after 7 d of aging. All muscles were cooked in hot water to an internal temperature of 66°C. The 2-h conditioning period yielded beef with the highest moisture and fat content, highest cooking yield and lowest protein level. ES did not have an influence upon physical characteristics of the ST roast, while the 7-d carcass conditioning period caused the least change in length and depth. ES lowered the pH and cooking loss after stimulation, improved the sensory panel tenderness scores and decreased the Instron® shear values of the cooked product. The most tender product was from the 7-d carcasses, while the 7-d excised muscle, and the beef given the 1-h conditioning period were the least tender. There was more variation in tenderness scores for the 8-mm than the 4-mm slices; but the lowest overall acceptability scores (4 mm and 8 mm) was for the 2-h conditioning period, which had low scores for flavor and flavor intensity. This problem could be overcome by adding a seasoning to the roasts before cooking.