196 JOURNAL OF FOOD SCIENCE—Vol. 66, No. 2, 2001 © 2001 Institute of Food Technologists Food Chemistry and Toxicology JFS: Food Chemistry and Toxicology Dry-Aging Effects on Palatability of Beef Longissimus Muscle R.E. CAMPBELL, M.C. HUNT, P. LEVIS, E. CHAMBERS IV ABSTRACT: Beef strip loins and short loins were vacuum aged for 7 or 14 d, then these cuts were dry aged for 7, 14, or 21 d. At 2, 9, and 16 d of post-dry-aging vacuum storage, strip steaks were analyzed for sensory, physical, and microbial differences. Controls were vacuum aged for 14 d. Dry aging for 14 and 21 d produced steaks with greater (P 0.05) dry-aged flavor, tenderness, and juiciness than controls or steaks dry aged for 7 d. Shear forces were lower (P 0.05) for steaks dry aged for 21 d. Time of vacuum storage before and after dry aging had minimal effects on development of dry-aged flavor attributes. Key Words: beef, dry aging, flavor, palatability, sensory Introduction A GING IS DEFINED AS HOLDING MEAT FOR A PERIOD OF TIME to enhance palatability (Anon. 1991). There are 2 types of aging. Vacuum or wet aging involves storing the product at refrigerated temperatures in a sealed barrier package, whereas in dry aging, the product is unpackaged and ex- posed to air at controlled temperature and relative humidity. Dry aging is no longer practiced widely because it results in weight losses up to 10% (Parrish and others 1991; Warren and Kastner 1992). Numerous studies have been conducted on beef palat- ability over the past 40 years. Although many have found aging makes meat more tender (Minks and Stringer 1972; Parrish and others 1991; Smith and others 1979; Warren and Kastner 1992), disagreement exists about palatability aspects other than tenderness. Warren and Kastner (1992) found dry-aged products had more beefy and brown- roasted flavor than vacuum-aged or unaged products. This agrees with work by Diles and others (1994) and Hodges and others (1974), but others have found no dif- ference or a decrease in palatability attributes, other than tenderness, of dry-aged products compared to unaged or vacuum-aged products (Davis and others 1975; Minks and Stringer 1972; Savell and others 1978). Hodges and others (1974) indicated beef flavor intensity increased in USDA Choice short loins after 15 d of dry aging, whereas USDA Standard short loins had less beef flavor intensity than controls. Beyond the scientific community, many believe in the flavor-enhancing effects of dry aging of beef (Ellis 1990). However, previous studies have focused only on times and conditions of dry aging. Virtually all fed beef is shipped in vacuum packaging; thus beef entering dry-ag- ing operations will have been vacuum aged, and dry-aged product likely will be vacuum packaged again for distribu- tion. Since no literature reports these combined effects, the present study examined the effects of time in vacuum before dry aging, duration of dry aging, and duration of vacuum storage after dry aging on the sensory, physical, chemical, and microbiological traits of beef longissimus muscle. Materials and Methods Storage Before Dry Aging Certified Angus Beef short loins (NAMP 174, n = 18) and strip loins (NAMP 180, n = 36) were obtained from commer- cial processors and shipped (3 °C) to the aging facility by commercial refrigerated transport. All loins arrived at the aging facility within 7 d of packing, and temperature moni- tors indicated loins were never frozen. Vacuum packaging had to be intact (no leakers) for product to be selected. Vac- uum-packaged short loins and strip loins were stored in vac- uum at 2 °C for 7 or 14 d from packing date. After vacuum storage, the tenderloin was removed from short loins, leav- ing the lumbar vertebra intact and attached to the strip loin. These shell loins (short loin with tenderloin removed) and the strip loins were placed on racks for dry aging. Truck tem- peratures were monitored via the truck controls and verified using the trucker log sheets. Plant temperatures were moni- tored via the plant charts. Dry Aging Dry aging was conducted at 2 °C and a relative humidity of 75%. Room temperature and humidity were monitored on continuous recording charts. After dry aging for 7 or 14 d, strip loins were trimmed and vacuum packaged. Shell loins were processed into strip loins (NAMP 180) by removing the lumbar vertebra after 21 d of dry aging, then trimmed, and vacuum packaged. All aged loins and control strip loins were shipped to the Kansas State Univ. meat laboratory in insulated shipping con- tainers (Kol-Boy Products, Cave Spring, Ga., U.S.A.) with re- usable ice packs (Kol-Boy Products). Receiving temperatures of loins ranged from 0 to 5 °C. Control strip loins (n = 18) were shipped so that they were always 14 d old when they were evaluated. Storage After Dry Aging Loins were stored in vacuum at 2 °C for 2, 9, or 16 d after dry aging. At each sampling time, loins were removed from the vacuum package, and 2 steaks, 2.5 cm thick, were cut,