Effects of electrical stimulation and post-slaughter chilling on biochemical properties of porcine muscles and factors affecting sausage batter morphology

Abstract

Three studies were conducted to determine (1) factors affecting measurements of water holding capacity, (2) effects of electrical stimulation and post-slaughter chilling on porcine muscle properties, and (3) factors affecting morphology of a sausage batter. In the first study, ten replications of supraspinatus muscle were assigned to the following expressible juice loss (EJL) treatments: pressures of 2000, 4000, 6000, 8000 and 10000 psig and times of 1, 3, 5, 7, and 9 minutes. In the second study, thirty pigs were slaughtered and assigned to the following stimulation and chilling treatments: left sides (L), electrically stimulated (ES); right sides (R), not electrically stimulated (NES); conventionally chilled, 0-2°C; blast chilled, -34°C; or chilled brine shower, -5.6°C. Four muscle groups based on visual color (predominantly white, intermediate, predominantly red, and shank) from the wholesale shoulders were used for determination of physical and chemical properties (pH, expressible juice loss (EJL), cooked juice loss (CJL), proximate composition, and salt-soluble protein (SSP)). In the third study, a conventionally made sausage batter was sampled during the following time periods: chopping at 2, 6, 9, 12, and 15 min; cooking/smoking at 30, 60, and 90 min. These samples were evaluated by light and transmission electron microscopy to illustrate structural changes in major components of meat (muscle, lipid, and collagen). Among all pressures and times used to determine EJL values, the combination of 8000 psig and 3 min was more optimum than the others (practically feasible, fairly high values, and less time consuming). Electrical stimulation (ES) significantly decreased pH value of the predominantly white group and numerically decreased pH values of all other muscle groups. ES significantly reduced SSP contents of predominantly red and of shank muscle groups and numerically reduced those of the other two muscle groups. ES increased (P < 0.05) CJL values of only the shank group. Regardless of ES, shank muscles had higher pH but lower CJL values (P < 0.05) than did the other groups...