The authors thank Certified Angus Beef; MacPak, LLC; Buckhead Beef Foods Co.; andTyson in Emporia, KS, for their support in this study.BEEF CATTLE RESEARCH 2009102One of eight treatment combinations (two cut styles × two aging methods × two agingtimes) were assigned randomly to the eight loin sections after 9 days of refrigerated storage. Sections assigned to unpackaged dry aging were aged on racks directly exposed tothe environmental conditions in the dry-aging cooler. Sections assigned to the bag agingtreatment were vacuum packaged in dry-aging bags (11.8 × 23.6 × 0.002 in.; thermoplastic elastomer made of flexible polymere and rigid polyamide; water vapor transmission rate 2500 g/m2/24 hours at 100.4°F and 50% relative humidity; MacPak, LLC,Wayzata, MN). These bags have a much greater than normal water vapor transmissionrate, which facilitates a more efficient exchange of water vapor from product surface tothe atmosphere, thereby simulating dry-aging conditions.Samples were taken for pH, shear force, moisture, fat, protein, thiobarbituric acid-reactive substances (TBARS), microbial, and sensory analyses. Weight losses were measuredthroughout the drying process on additional loins and sample loins.Results and DiscussionThe loins selected had an expected pH and typical composition for more highly marbledcuts of the longissimus lumborum muscle. Tenderness, juiciness, mealiness, and Warner-Bratzler shear force did not differ (P>0.05) among the four cut style × aging methodcombinations (Table 1). Overall, aged beef flavor was higher for steaks from strip loinsthan for those from shell loins. In addition, brown roasted notes also tended (P