Microbiological safety of dry-aged meat:a critical review of data gaps and research needs to define process hygiene and safety criteria

Dry-aged meat is gaining popularity among food business operators and private consumers. The process is carried out in aerobic conditions by hanging beef carcasses or placing subprimal or primal cuts in a dedicated cabinet for several weeks or even months while controlling the environment through the management of process parameters such as temperature, relative humidity, and airflow. In this review, we present a critical evaluation of the literature to evaluate tools to manage the process to guarantee foodsafety and identify critical control points, as well as good hygienic and manufacturing practices.In controlled aging conditions, only Listeria monocytogenesand Yersinia enterocoliticacan multiply, while a reduction in the number of Salmonellaspp. andEscherichiacoliO157:H7 is generally reported. Enterobacteriaceaeusually decrease on the surface of the meat during maturation; thus, for the purpose of the hygienic evaluation of the production process, a count no higher than that of unmatured meat is expected. Besides, various studies report that the total bacterial count and the spoilage microorganisms significantly increase on the surface of the meat, up to 5-6 Log CFU/g in the absence of visible spoilage. Bacteria of the Pseudomonasgenus tend to progressively replace other microorganisms during maturation; thus, the total mesophilic or psychrophilic bacterial load is not a good indicator of process hygiene for matured meat.Critical parameters for the control of the process are temperature, relativehumidity, and ventilation, which should be monitored during the process. For this reason, equipment designed and certified for dry aging must be used, and the manufacturer must validate the process. Food business operators must apply general good manufacturing practices (GMP) and good hygiene practices (GHP) for meat processing and some GMP and GHP specific for dry aging.Several research needs were identified, among them the evolution of the populations of L. monocytogenesand Y. enterocoliticaand the microbiology of the inner parts of the dry-aged meat.IntroductionMeat consumers are demanding products of high and consistent quality with a distinctive flavor and aroma able to provide a particular sensorial experience when consumed (Álvarez et al., 2021). Dry-agingis a process used by high-end food service restaurants and upscale meat markets to enhance the palatability of meat, encompassing a combination of biochemical/biophysical processes that are naturally caused by a complex group of endogenous proteases and lipases altering the muscle structural integrity, meat color surface, and palatability (Khazzar et al., 2023). Indeed, proteolysis causes muscle tissue to mature, producing a typical taste with a unique flavor and improving the tenderness and juiciness of meat.For centuries, cold storing was a common way for butchers to preserve and tenderize beef, but the advent of vacuum packaging, along with increased efficiencies in beef processing and transportation, determined the abandonment of dry aging in favor of the wet aging process (Dashdorj et al., 2016), where beef is put in a vacuum-sealed package and stored in a controlled environment for a specific period of time. In recent years, the dry aging technique has attracted the attention of retailers, the food industry, and restaurants in the United States, Australia (Meat and Livestock Australia, 2016), Asia (Dashdorj et al., 2016), and also Europe (EFSA BIOHAZ Panelet al., 2023). The process is carried out in aerobic conditions by hanging beef carcasses or subprimal or placing primal cuts in a refrigerated room and aging for several weeks or even months while controlling the environment through the management of process parameters, namely temperature, relative humidity (RH), and air flow.Dry aging can be performed in meat processing plants, in which the primal or subprimal cuts are processed for about 7-28 days, and then, after cutting and packing, they are ready for sale. Dry-aged steaks are offered mostly in fine restaurants, upscale grocery stores, gourmet steak companies, and specialized meat shops (Dashdorj et al., 2016). On the other hand, always more frequently, small producers sell their products directly to consumers at meat boutiques or restaurants. This business