## 2 Instrumental Measurement of Red Meat Sensory Quality
### Texture  
The International Standards Organization [38] defines texture as the combination of the rheological and structural attributes of a food product perceptible using mechanical, tactile, and where appropriate, visual and auditory receptors. Among the textural features of red meat, tenderness is widely acknowledged as the leading factor in determining palatability [39].  
The consensus is that tenderness in red meat is largely influenced by post-mortem events [40]. While factors such as nutrition and selective breeding can be employed to improve animals' potential for high meat quality, their effectiveness may be limited if post-mortem factors are not ideal during the conversion of muscle to meat [41]. In the post-mortem period, a series of complex biochemical and physical changes occur in muscle tissue as it transitions into meat [8]. This process begins soon after the animal is slaughtered,disrupting its usual cellular functions [42]. As the animal undergoes exsanguination and experiences a lack of oxygen, the skeletal muscle attempts to maintain the cellular balance by continuously producing and utilizing adenosine triphosphate (ATP) [43]. However, without oxygen, the muscle breaks down glycogen and other high-energy compounds anaerobically to create ATP [44]. This anaerobic process is not as efficient as aerobic metabolism, leading to an imbalance between ATP production and consumption [8]. Over the following hours post-mortem, the muscle loses its ability to generate ATP, resulting in the irreversible binding of myosin to actin, causing rigor mortis to establish across the tissue and muscle functionality to diminish [45]. Rigor mortis typically begins between 2 to 6 h after death, influenced by factors such as the species, muscle type, and pre- and post-slaughter conditions [46]. Following rigor onset, there is a subsequent conditioning or ageing process, which occurs during refrigerated storage over days and some weeks, during which proteolytic breakdown of cytoskeletal proteins leads to the loss of muscle cellular structures, causing a decrease in muscle tension and tenderisation of the meat [47]. Factors such as the moisture and fat content, as well as the effects of the chilling regime, tenderization, and cooking on proteins, also influence the juiciness of the meat [48]. Therefore, a combination of pre- and, more importantly, post-slaughter factors can greatly influence the ultimate tenderness and juiciness of meat [49].  
The majority of instrumental methods for evaluating meat texture are based on mechanical testing, including measurements of the meat resistance to forces acting on it that are higher than gravity [50]. The majority of the data used to assess cooked meat tenderness are assessed using Warner-Bratzler shear force (WBSF) [51]. However, this technique has certain limitations, including the time required for cooking, cooling, and obtaining six 1.27 cm cores to assess the tenderness [52], making it less feasible for routine industrial purposes. Sample modifications, such as the shape and diameter [53], along with changes in blade characteristics like the cutting edge angle [54], can affect the results. The Kramer shear cell test, similar to the WBSF, measures both compression and shear, rather than a single mechanical property, which could be seen as a limitation of this method [55]. There are studies that show the potential of the Kramer shear cell and WBSF for the prediction of meat texture [56]. The single compression test is another method for assessing meat texture, but it is less frequently used compared to the double compression test, known as texture profile analysis (TPA), which provides more detailed information. TPA is a compression method that evaluates various textural properties, including the tenderness, chewiness, adhesiveness, cohesiveness, and springiness in a single test [55]. The parameters are categorized into primary (hardness, springiness, adhesiveness and cohesiveness) and secondary (gumminess, chewiness and resilience) parameters [53].