ENZYMIC LIPID PEROXIDATION IN BEEF MUSCLE MICROSOMES AS AFFECTED BY ELECTRICAL STIMULATION AND POSTMORTEM MUSCLE EXCISION TIME

Left sides of 10 beef carcasses were electrically stimulated at I h postmortem; right sides were not stimulated. Longissimus dorsi (LD) and trapezius (TP) muscles were removed from stimulated and nonstimulated sides after 1.5 and 24 h of chilling (0–2°C). Microsomal lipid peroxidizing activity (the amount of malonalde-hyde produced per mg of microsomal protein) was not affected by electrical stimulation, was higher for muscles removed after 24 h chilling than for those removed after 1.5 h chilling, and was higher for TP than for LD muscles. Differences observed in lipid peroxidizing activity could not be explained readily by microsomal fatty acid compositions.