## 3 Results and Discussion
### Assessment of Technological Quality of Stored Meat

Table 3: Changes in values (mean \(\pm\) standard deviation) of pH, maximum puncture force (F\({}_{\text{P}}\)), deformation (D\({}_{\text{P}}\)), and cooking loss, from meat of chickens stunned using the own-construction (OC) and Polish company (PLC) devices during 14 days of storage. compared to fresh meat (Table 1). The F\({}_{\rm P}\) value of the fillets of chickens stunned using the PLC device stayed the same at about 28 N. After 9 days of storage, the F\({}_{\rm P}\) value of the fillets of chickens stunned using the OC device was approx. 22 N, and the F\({}_{\rm P}\) value of the fillets using the PLC device decreased to approx. 21 N. During 12 to 14 days of storage, F\({}_{\rm P}\) values, regardless of the type of device, were at a similar level of approx. 23 N. Statistical analysis of the influence of meat storage time on changes in F\({}_{\rm P}\) values revealed significant differences (\(p<0.05\)) only in the case of stunning chicken fillets using a PLC device. The deformation values (D\({}_{\rm P}\)) of chicken fillets stunned using the OC device were, similarly to the F\({}_{\rm P}\) values, at a similar level (8.50-8.02 mm) throughout the entire storage period, and did not differ significantly. The D\({}_{\rm P}\) values of chicken fillets that were stunned using the PLC device and stored for 7 and 9 days were 9.92 and 7.55 mm, respectively. After 12 days of storage, they increased to 8.50 mm, and after 14 days, they decreased to 8.20 mm. Statistical analysis of the influence of the storage time of meat from chickens stunned using a PLC device on changes in D\({}_{\rm P}\) showed, similarly to F\({}_{\rm P}\), significant differences at the \(p<0.01\) level. The type of device used (OC/PLC) had a significant effect (\(p<0.01\)) on the variation in the D\({}_{\rm P}\) value of the fillet stored for 7 days (Table 3). A significant (\(p<0.05\)) reduction in the F\({}_{\rm P}\) value may be caused by the initiation of proteolytic processes and the release of amino acids, which also reduce the pH of meat [32]. However, the lack of significant changes in F\({}_{\rm P}\) and D\({}_{\rm P}\) during 14 days of storage proves the beneficial effect of the OC device on meat tenderness (maturity), which is one of the most important quality determinants for the consumer. By maintaining their native structure, myofibrillar proteins retain their water-holding capacity, providing more desirable textural properties [33]. According to [PERSON] [14], structural changes in muscle tissue and meat tenderness are influenced by the frequency of electric current flowing through the chicken body during stunning. As the current frequency (f) increases, cell membranes lose their impermeable properties, and the current flows through both intracellular and extracellular spaces. At f = 800 Hz, the current flows evenly through the bird's entire body, causing degradation of the muscle tissue structure to the same extent. The beneficial effect of high current frequencies (480, 600, and 750 Hz) compared to low frequencies (f = 50 Hz) on improving meat tenderness was also demonstrated by [PERSON] et al. [34] and [PERSON] et al. [9]. The authors described its beneficial effects as a significantly higher myofibril fragmentation index and lower glycogen content in muscles after slaughter. Although cooking losses are an important indicator of the meat's water-holding capacity during thermal processing, the test results showed that the values of cooking loss from chicken meat stunned using the OC and PLC devices did not differ significantly at any stage of storage.