| Abstrakt: |
The objective of this study was to evaluate the effects of extended aging and modified atmospheric packaging on beef LM color. Using a randomized complete block design, each beef longissimus lumborum muscle (n = 10; USDA Choice, 3 d postmortem) was equally divided into 3 sections and randomly assigned to 1 of 3 aging periods (21, 42, or 62 d at 2°C). After respective aging, each loin section was cut into four 2.5-cm-thick steaks and randomly assigned to 1 of 3 packaging types (PVC, HiOx-MAP [80% oxygen and 20% carbon dioxide], or CO-MAP [0.4% carbon monoxide, 69.6% nitrogen, and 30% carbon dioxide]). The steaks were displayed under continuous fluorescent lighting for 6 d, and surface color was determined daily using a HunterLab Miniscan XE Plus spectrophotometer and a visual panel. The fourth steak was used to characterize oxygen consumption (OC), lipid oxidation, and metmyoglobin reducing activity (MRA) on 21, 42, and 62 d (before display). On d 6 display, MRA, OC, and lipid oxidation also were measured. An increase in aging time decreased (P < 0.0001) muscle pH. Loin sections aged for 42 and 62 d had a lower (P < 0.0002) pH compared with loin sections aged for 21 d. An aging period × packaging × display time interaction (P < 0.0001) resulted for a* values (redness), chroma, and visual color (muscle color and surface discoloration). As aging time increased, HiOx-MAP had the most discoloration (P < 0.0001) compared with other packaging types on d 6. At all aging periods, steaks packaged in CO-MAP had greater (P < 0.0001) MRA on d 6 than PVC and HiOx-MAP, whereas steaks packaged in HiOx-MAP had the least MRA (P < 0.0001). There were no differences (P = 0.34) in thiobarbituric acid reactive substances values between steaks aged for 21 and 42 d when steaks were packaged in CO-MAP and displayed for 6 d. However, steaks packaged in HiOx-MAP and displayed 6 d had greater (P < 0.0001) lipid oxidation than COMAP. Steaks packaged in HiOx-MAP had a lower (P < 0.0001) OC compared with PVC and CO-MAP when aged for 42 and 62 d. There were no differences (P = 0.49) in OC between steaks packaged in PVC and HiOx-MAP when aged for 21 d and displayed 6 d. The results indicate that extended aging is detrimental to color stability when packaged in PVC and HiOx-MAP. However, steaks in CO-MAP had stable red color during display. Decreased color stability in PVC and HiOx-MAP could be associated, in part, with decreased MRA and OC. [ABSTRACT FROM AUTHOR] |
