Changes in meat metabolite set depend on postmortem handling of meat. Dry aging allows moisture evaporation under aerobic conditions with a relatively long aging period to obtain a beneficial dry-aged flavor . A dry aged beef under a condition of 3 °C with 0.2 m/s air velocity for 3 weeks improved the beef palatability in a sensory panel evaluation, compared with a general wet aging and other dry storage conditions, with higher BCAAs and IMP contents . The airflow in this method might simply increase flavor-associated metabolites by water evaporation; however, other unknown factors are also likely to be involved. The effect of the in-bag dry aging technique, using a waterpermeable bag, on lamb muscles was assessed using a metabolomic approach . During 21 days of aging, metabolomic differences were observed between the two aging methods and muscles . Dryaged lambs showed higher levels of AAs, dipeptides, and energy metabolism-related metabolites than those in wet-aged lambs. According to the OPLS-DA model using REIMS data, differences between the two different types of aging methods and different types of muscles were distinguished.