Effects of dark storage and retail display on beef chuck and round muscles enhanced with ammonium hydroxide, salt, and carbon monoxide

¹ Animal Science Department, University of Nebraska, Lincoln, NE, 68583

^* To whom correspondence should be addressed. E-mail: ccalkins1{at}unl.edu.

	Abstract

The objective of this study was to determine the retail shelf stability of beef chuck and round muscles enhanced with ammonium hydroxide, salt, and carbon monoxide. A split plot design was used for each of 3 muscles (triceps brachii (TB), biceps femoris (BF) and rectus femoris (RF)) with 2 treatments (0 and 20% pump), 3 dark storage periods (1, 2 and 3 wk), and 3 replications in the whole plot and retail display period as the split plot. There were a total of 12 subprimals per treatment per dark storage period (n = 72 each). Individual steaks were cut to a thickness of 2.54 cm and packaged in a modified-atmosphere package (MAP). The TB was packaged in a high oxygen MAP (80% oxygen, 20% carbon dioxide). The BF and RF were packaged in a low oxygen MAP (100% carbon dioxide). At the completion of each dark storage period, steaks were subjected to 7 d of simulated retail display. Steaks were used for objective and subjective color measurements, total plate counts, and determination of retail purge and oxidation. For all muscles, total plate counts were always numerically higher in injected steaks. Triceps brachii steaks held in dark storage for 3 weeks and displayed at retail for 4 or more days all exceeded 10⁷ log of cfu/cm² for aerobic plate count. Biceps femoris and RF steaks packaged in a low oxygen MAP had much lower bacterial counts, with levels below 4.2 log of cfu/cm², even after 7 d of retail display. Oxidation values from the TB were extremely high (ranging from 12.3-26.6), while the BF and RF had values that were much lower ( 1.0 mg malonaldehyde/kg muscle)–likely due to the oxidation occurring in a high oxygen MAP for the TB. Enhanced TB steaks proved to have more color stability (less discoloration) than non-enhanced. In addition, the BF and RF (low oxygen MAP) steaks had better color stability (more stable redness values) than TB steaks (high oxygen), although TB steaks initially exhibited a brighter red color. Retail display life was enhanced by packaging in 100% carbon dioxide and injected steaks exhibited greater color stability in retail display than control steaks.

Key Words: Enhancement, MAP, retail display, shelf life