Influence of Electrical Stimulation on Palatability of Hot-Boned, Pre-Rigor and Cold-Boned, Post-Rigor Frozen Beef Roasts ¹

The effects of electrical stimulation on palatability of hot-boned, pre-rigor and cold-boned, post-rigor frozen beef roasts were studied by use of 16 steer carcasses. Both sides of 8 carcasses were electrically stimulated (1.5 amps; 100 - 1 s impulses); sides from the other 8 carcasses served as controls. One side of each carcass was hot-boned and the remaining side was boned following a 48 h chill (2 C). Roasts from the rump portion (anterior one-fourth) of the biceps femoris muscle were vacuum-packaged and frozen (-20 C). Following a 48-h thaw (0 C). roasts were weighed, measured for length, width and depth, seasoned, placed in cooking bags and roasted to 62.5 C. Cooking losses were less (P<0.06) for hot-boned, pre-rigor frozen vs. cold-boned, post-rigor frozen roasts. Raw pH (post-freezing) was lower (P<0.01) for hot-boned than cold-boned roasts. No differences (P>0.05) were noted in shape changes for stimulation or chilling. Using triangle tests, untrained panel members were able to distinguish controls from electrically stimulated roasts and hot-boned from cold-boned roasts when served as thick (1.27 cm) or thin (2 mm) samples. Thick and thin samples of cold-boned roasts were preferred over hot-boned roasts. For roasts from carcasses that were not electrically stimulated, 62.6% preferred cold-boned roasts for thick samples while 61.4% preferred cold-boned roasts for thin samples. Cold-boned roasts from electrically stimulated carcasses were preferred over hot-boned roasts, 56.5% (thick) vs. 51.5% (thin). Warner-Bratzler shear force results indicated that hot-boned, control roasts required 79% more shear force than cold-boned roasts, but roasts from electrically stimulated carcasses required 14% more force to shear hot-boned than cold-boned roasts.