Effect of Chilling Method and Electrical Stimulation on Pork Quality

Abstract
Forty-five market weight hogs were conventionally slaughtered, carcasses split, left sides electrically stimulated (ES) and right sides not ES (NES). The first group of 30 carcasses (Group 1) was divided into six subgroups of five carcasses each, and sides were assigned to one of three chilling methods (BLAST = 3 h at −34 C, then 21 h at 2 C; CONV = 2 h at 2 C; BRINE = 3 h under a −5 C brine shower, then 21 h at 2 C). Group 2 consisted of 15 carcasses, divided into three subgroups of five carcasses each, and paired sides were assigned to BLAST, CONV, or BRINE chill. Electrical stimulation did not affect temperature decline of the leg or loin. Chilling method did produce differences in temperature decline. Extrapolation of the data indicated that fabrication procedures could begin at 9.5, 11 and 14.5 h postmortem for BLAST, BRINE and CONV, respectively; whereas optimal temperature for extending shelf-life would be reached at 12, 20 and 24 h postmortem for the respective chill methods. Electrical stimulation did not affect muscle color or firmness of the loin or shoulder, nor muscle separation of the shoulder; however, ES did affect muscle color (paler), firmness (softer) and separation (more extensive) of the legs. More rapid chilling (BLAST or BRINE) increased muscle color scores for legs. The BLAST method improved (over BRINE and CONV) the firmness of all cuts and decreased the separation of the shoulder and leg. Where interactions of stimulation × chilling were not evident, only the flavor desirability and overall palatability of cured biceps muscles were affected by stimulation, with ES having lower (P<.05) ratings than NES. Interactions of stimulation × chilling method and differences that were observed are discussed.