Carbon monoxide, high-oxygen packaging may impact beef strip loin quality.

Carbon monoxide (CO), which can be used as a modified atmosphere packaging (MAP) gas, has the potential to extend the color shelflife of case-ready beef. Scientists at the University of Illinois evaluated the effects of CO and compared them to the way traditional high-oxygen (HiOx) MAP packaging impacts the quality of beef.

The researchers enhanced strip loins to 107.5% over their initial weight by using a commercial phosphate-salt solution. The steaks were cut and packaged in atmospheres containing 0.4% CO or 80% [O.sub.2]-20% [CO.sub.2] (HiOx). The steaks were aged in the dark and then placed in a lighted retail display case.

Trained sensory panelists visually evaluated the steaks on days 12 to 14 and on days 26 to 28 using a seven-point color scale and a five-point surface sheen scale. On days 14 and 28, the packages were opened and the product cooked for consumer evaluation. All raw steaks were moderately red. After 28 days, CO-packaged steaks were redder than at 14 days but not as red as HiOx-packaged steaks at 14 days.

After 14 days, HiOx-packaged steaks had more surface sheen than did the CO-packaged steaks. However, after 28 days, the sheen on the CO steaks was not different from the sheen on 14-day HiOx packaged steaks. Beef flavor, off-flavor and overall acceptability of the CO steaks did not differ from HiOx steaks. Off-flavor was low and overall acceptability was good. When the data were pooled over the CO and HiOx treatments after 13 and 14 days, the steaks appeared relatively dry. However, their surfaces displayed more viscous sheen by day 26 and even more by days 27 and 28.

It appears that CO-based packaging had no effect on the flavor or acceptability of the product and only a minimal effect on other characteristics. If the CO environment provides microbiological stability through 28 days, you can be expect that raw product appearance characteristics will not differ from steaks in traditional HiOx packaging that have been held for 14 days.

Further information. M. Susan Brewer, Department of Food Science and Human Nutrition, University of Illinois, Urbana-Champaign, 202 Agricultural Bioprocess Laboratory, 1302 W. Pennsylvania Dr., Urbana, IL 61801; phone: 217-244-2867; fax: 217-244-1873; email: msbrewer@uiuc.edu.