Shelf-life characteristics of steaks from steers supplemented with vitamin E and differing in USDA Quality Grade

Abstract

One hundred thirty-one Bos indicus x Brown Swiss steers of Mexican origin were assigned randomly to two Treatments (TRT): Control (CONT) (n=66) or 500 IU/day vitarnin E supplementation (VITE) (n=65) for the last 147 days of commercial feeding. Following commercial slaughter and carcass evaluation, IMPS 107 ribs were obtained based on USDA Quality Grades (QGRADE) of Select-(n=8 TRT and n=8 CONT), Choice-(n=7 TRT and n--9 CONT) and Choiceo (n=6 TRT and n=6 CONT) within TRT. Both TRT had similar feedyard and carcass characteristics. Dietary vitarnin E steaks showed increased CIE a*(redness) values, reduced oxidative rancidity (TBA number), and more desirable Lean Color (LCLR) and Percentage Lean Discoloration (DISCL) panel scores under simulated retail display. There was a significant TRT by shelf-life day (DAY) interaction for TBA number and Objective CIE a* values with steaks from VITE steers having more desirable TBA and CIE a* values after Day 3. Rib steak cc-tocopherol content and TBA number were dependent on the interaction of TRT and QGRADE. Vitamin E Select- steaks had lower oc-tocopherol content (I .6 gg/g) than either VITE Choice-(2.6 ttg/g) or Choiceo (2-9 gg/g) steaks. Furthermore, VITE Select-and CONT steaks were not different in cc-tocopherol content (1.5 gg/g, 1.3 gg/g, and 1.4 gg/g for CONT Select-, Choice-, and Choiceo, respectively). TBA values for QGRADE within TRT were different (P<.05) with Select-steak TBA values being higher than both CONT Choice- and Choiceo steaks as well as all VITE steaks. Linear regression and scatter plot analyses of Hue Values according to cctocopherol content for DAY 7 steaks showed an apparent cubic relationship. Panel LCLR and DISCL scores depended on the three-way interaction of QGRADE, DAY and TRT. As QGRADE increased, shelf-life characteristics were, past DAY 5, more desirable in CONT steaks, but the trend was just the opposite in VITE steaks. Control Select-, Choice-, and Choiceo LCLR scores were 2.5, 3.2 and 3.4, respectively, for DAY 7, yet TRT Select-, Choice-, and Choiceo LCLR scores were 5.2, 3.8 and 4.4, respectively. DISCL scores followed a similar trend, except Choice-and Choiceo steaks did not differ within Treatment.