## 1 Introduction  
Today, there is an increasing demand for high-quality products that offer significant culinary experiences. This has once again brought aged meat, which was beloved by our ancestors, into the spotlight [1]. Beef is the type of meat that is most commercially important for aging. Meat contains an average of 75.5% water, which can be either bound (3-5%) or present in a free state [2, 3]. Following slaughter, during the aging process, numerous biochemical changes occur in the meat, greatly influencing its subsequent organoleptic properties, particularly its texture. After the slaughtering there are three main stages: the pre-rigor state, rigor mortis, and the subsequent aging phase. The pre-rigor phase, also known as the phase before rigor mortis, lasts approximately 3-6 h [4]. During this phase, anaerobic (glycolysis) processes become more prominent than aerobic (terminal oxidation) processes, resulting in less adenosine triphosphate (ATP) production. Glycogen begins to convert to lactic acid, initiating a robust formation of phosphoric acid in the tissues, which lowers the pH of the meat [5]. Meanwhile, breakdown processes continue to operate. The end of postmortem metabolism is characterized by substrate depletion and the inactivation of phosphofructokinase-1 enzymes [6]. By this time, ATP stores are depleted from the cells, and cells are forced to fully transition from aerobic to anaerobic processes [4]. Actin and myosin filaments tightly bind to each other, resulting in the stiffening of muscle fibers. This marks the onset of rigor mortis, the phase of stiffness [4]. Then, the pH decreases significantly (pH = 5.6-5.4), and the proteins denature [7]. Structural proteins in the meat undergo changes that will significantly affect their texture and taste later [6]. The water-binding capacity of meat decreases during rigor mortis, its texture becomes firm, and its surface becomes shiny. Rigor mortis is followed by the post-rigor stage, during which the pH value increases again, muscles relax, meat becomes tender, and its water-binding capacity begins to improve. However, the restored pH balance facilitates the action of calpains, which function well at neutral pH [8]. These changes are followed by the maturation stage, during which proteolytic enzymes exhibit broad activity. Several factors, such as genetics, pre-slaughter handling, or post-slaughter treatment, influence this stage. Proteolytic enzymes alter the properties and structure of proteins, thereby affecting their taste. They also begin to break down other cell molecules, resulting in the formation of smaller, flavor-rich products from larger, tasteless molecules. Amino acids rich in taste and aroma are generated from proteins, while high-intensity flavor fatty acids are formed from fats and fat-like membrane components. During cooking, the reaction of these components will result in an even more intense and aromatic flavor [9]. Another important process during meat maturation is the activity of calpain enzymes, which play a crucial role in achieving tenderness [10]. These enzymes weaken the bonds of carrier proteins that anchor the contractile filaments. The high enzyme activity observed during meat maturation lasts approximately 14 days [11]. There are mainly two primary methods of aging: dry aging and wet aging. In the case of dry aging, the meat is aged at a specific temperature, in controlled airflow and humidity without packaging for a defined period. In wet aging, which is the topic of this research, the meat is stored in vacuum-sealed packaging throughout the aging process until it reaches its maximum tenderness, flavor, and juiciness [12]. Aging time can vary significantly among different species, but beef, veal, and rabbit meat require similar aging times. During a 10-day aging process at 1 \({}^{\circ}\)C, measts reached 80% maturity. Among the meats of different animals, beef requires one of the longest aging times [13].