Relationships and interrelationships of selected antemortem and postmortem factors to meat tenderness and palatability

Abstract

Steers from three breed-types (Brahman, Angus, Brahman X Angus; n = 25 each) were placed on a high-concentrate diet and five animals from each breed-type were slaughtered after zero, 56, 112, 168 and 224 days on feed. Right sides were electrically stimulated (ES) with high-voltage current. Sensory evaluations, Warner-Bratzler shear force values, pH decline, temperature decline and the distribution and amount of cathepsin B, cathepsin H and β-glucuronidase were obtained from the longissimus dorsi and the biceps femoris. USDA quality and yield grade factors were evaluated after 24 hours of chilling. Results indicate that changes in the amount or distribution of β-glucuronidase were associated with alterations in sensory panel ratings for connective tissue. Relationships of cathepsin B and cathepsin H to tenderness and palatability were low. High muscle temperature, coupled with a low pH, had a significant influence on beef tenderness. This effect was not entirely due to the reduction of cold shortening. Alterations in temperature and pH can be achieved by use of ES or by increasing the duration of the feeding period. Electrical stimulation was of greater benefit to meat tenderness than were any of the other factors considered, regardless of time on feed, or breed. The relationship between length of feeding period and muscle temperature of pH and their effect on palatability appeared to be a result of increased subcutaneous fat thickness and carcass weight.