Factors influencing microbiological, physicochemical quality, and yield of dry-aging beef

The dry-aging business is widely popular across Japan. In Okinawa, most dry-aged beef is usually produced using imported beef. Microorganisms are likely to thrive on the surface of imported beef during transport to Japan, despite storage at chilled temperatures. To prevent the growth of microorganisms in such cases, accurate control of aging is critical. A fundamental understanding on a scientific level with regard to the maintenance of hygiene is essential for developing a method for dry-aged products. In this study, changes were analyzed in the water activity and the microorganisms on beef meat, in addition to moisture and trim losses (aging loss), during aging under varying levels of relative humidity and temperature, with or without airflow, and mold treatment. As the relative humidity during the aging process was lower, the number of microorganisms was lower but the aging loss was higher. Similarly, as the temperature during the aging process was lower, the number of microorganisms was lower, and the aging loss remained almost unchanged. Hence, according to the results, it is essential to lower water activity as quickly as possible to 0.94 by keeping relative humidity below 75% as a guide and freezing temperatures below 4°C but above −2 to −3°C for meat is strongly recommended. In addition, direct airflow to the beef during the aging process prevented the growth of microorganisms. In particular, it decreased Escherichia spp. but increase aging loss. As a result, air circulation via moderate airflow is recommended during the aging process. Besides, it became apparent that mold treatment did not prevent the growth of microorganisms.