## 1 Introduction  
The appearance of beef offered at retail is the most important factor considered by consumers when making purchasing decisions [1, 2]. Consumers analyze their perceptions of meat color, the amount of fat and marbling [3, 4, 5]. According to consumers, color closely correlates with the quality of meat, including its freshness and suitability for consumption [6, 7]. In general, beef color should be bright red and intense since any color deviations are associated with a decrease in quality and freshness [8, 9, 10, 11]. Moreover, consumers often predict the sensory quality of the final, ready-to-eat dish based on the color of fresh meat [1, 5]. If meat color is not consistent with their expectations, consumers will not decide to buy the product, even if the remaining attributes, assessed visually, are satisfactory. Meat color is the product of various chemical forms of myoglobin [2, 8, 10, 12, 13, 14] whose concentration depends, among others, on the breed, gender, age, and diet of animals, breeding methods, muscle pH and metabolism, enzymatic systems, and extrinsic factors such as temperature, oxygen availability, type of lighting, and surface microbial growth [5; 15]. The proportions of different myoglobin forms on the surface of meat change as a function of time (ageing, blooming) [1]. Under the influence of atmospheric oxygen, the color of freshly cut beef turns bright red due to the oxygenation of the myoglobin molecule (deoxymyoglobin to oxymyoglobin) [5; 7; 13]. This process, which is usually referred to as blooming [16], depends on oxygen availability, oxygen diffusion into the meat, and mitochondrial oxygen consumption rate [17]. Blooming time is also affected by the type of muscle and its location in the carcass. The muscles that were more active in live animals contain more myoglobin, which ultimately affects the values of chromatic parameters during blooming [18]. In addition to myoglobin, mitochondria also remain biochemically active in post-mortem beef muscles, and they can influence meat color and its stability. Myoglobin molecules and mitochondria compete for oxygen, which influences the intensity of early bloomed color and the formation of oxymyoglobin [19]. The differences in the color and quality of beef muscles may also result from the composition of muscle fiber types [8; 20]. [PERSON] et al. [21] characterized muscle fibers by histochemical analysis (fiber number percentage, area percentage, and diameter) and found that the differences in the composition of muscle fiber types between cattle muscles affected their color, marbling, and tenderness. All of these factors significantly affect meat color, and therefore it is difficult to establish a universal blooming time, which may vary depending on the breed and age of animals as well as the production system. The researchers who studied different beef muscles have reported differences in blooming time. [PERSON] et al. [22; 23] noted that up to 90% of color changes in beef occurred during the first 60 min after steaks had been cut. [PERSON] and [PERSON] [18] found that at least 16-18 min were needed for blooming in the semitendinosus (ST) muscle 48 h post-mortem, whereas [PERSON] et al. [16] estimated it for 10-12 min. [PERSON] et al. [9] allowed beef samples to bloom for 30-45 min at 1-2 degC before the first color measurement was taken, whereas [PERSON] et al. [15], [PERSON] et al. [24], and [PERSON] et al. [25] performed color measurements in the longissimus lumborum (LL) muscle after 60 min blooming. The cited authors analyzed the rate of changes in color parameters a * and b *, as well as color stabilization time. However, it seems interesting to use coefficient \(\Delta\)E to determine color stabilization time, indicating the absence of significant differences in color coordinates over time. \(\Delta\)E represents the total color difference by accounting for combined changes in the values of L *, a *, and b *.