Relationship between Physiological Maturity and Retail Shelf Life in Heifer Carcasses

Right sides of A (n = 24), B (n = 23), and C (n = 24) maturity heifer carcasses were used. Carcasses under 30 mo of age based on dentition, and with a “small” (Sm) to “moderate” degree of marbling were selected. Beef strip loins (IMPS 180) and outside rounds (IMPS 171B) obtained from these carcasses were purchased from AB Foods (Toppenish, WA) and transported to the University of Idaho Meat Science Laboratory. Following a 14-d aging period, wholesale cuts were removed from vacuum packaging and ischiatic heads were removed from outside rounds to produce trimmed flats. Two 2.54 cm-thick steaks were cut from the trimmed flats and anterior ends of strip loins. One steak was used to measure retail fluid loss and color stability and the other was used to measure lipid oxidation. Steaks were placed in white Styrofoam trays with the freshly cut surface exposed and overwrapped with an oxygen permeable PVC film. Steaks used to determine retail color stability were weighed prior to packaging and displayed in a glass-fronted retail display case at 2.6°C for 6 d. Steaks were allowed to bloom for at least 60 min and then two objective color measurements per steak were taken using a Hunter MiniScan EZ. This represented d 0 of retail display, and subsequent color measurements were taken on d 1, 2, 3, 4, 5, and 6. The instrument was set to illuminant A and Commission International de l’Eclairage (CIE) L*, a*, and b* values were recorded. Three evaluators measured oxygenated lean color, surface discoloration, % discoloration, amount of browning, and color uniformity on each day of retail display. Following 6 d of retail display, steaks were removed from packaging and reweighed to determine retail fluid loss. Thiobarbituric acid reactive substances (TBARS) were quantified in samples obtained from steaks on d 0, 2, 4, and 6 of retail display. Data were analyzed using the Mixed Model procedure of the Statistical Analysis System (SAS Inst. Inc., Cary, NC) and significance was determined at P < 0.05.