## 3 Results and Discussion
### Answering, Moisture Content and Cooking Loss
Changes in endogenous bioactive compounds, includingcarnosine and anserine, in the meat of indigenous Korean chicken varieties, depending on the age of the bird and the cooking process used, were analysed by [PERSON] et al. [52]. The authors demonstrated the predominant share of anserine in chicken meat, both in the breast muscle and leg meat. The authors showed that the average content of carnosine in the meat (taking into account the breast muscle and leg meat) was 127.24 mg/100 g, while the average content of anserine was 427.00 mg/100 g. As a result of cooking the meat to a core temperature of 72 \({}^{\circ}\)C, the content of carnosine and anserine decreased to 99.43 mg/100 g and 334.85 mg/100 g, respectively. The main reason for the loss of dipeptides during heat treatment is the high solubility of dipeptides in water, in particular carnosine. [PERSON] et al. [18], after analysing the impact of various heat treatment methods on the content of dipeptides in beef and turkey products, showed that the final amount of dipeptides in the products may be lower than the initial content by up to 70%, with the highest losses of carnosine and anserine found in cooked products. [PERSON] et al. [52], using boiling in water, showed much lower losses of carnosine and anserine. In this case, the retention of anserine was 82%, while the retention of carnosine was 78% in the breast muscle and 86% in the leg meat. Also, [PERSON] et al. [21] showed a decrease in the content of carnosine and anserine as a result of the heat treatment of pork meat in a combi-steam oven, heating the samples to a final temperature of 73 \({}^{\circ}\)C. [PERSON] et al. [23], by analysing the processing conditions (temperature and time) using the sous vide method on the nutritional characteristics of pikeperch fillets, showed that the initial anserine content in pikeperch tissue did not change significantly as a result of heating SV65 (time 45 min) and SV75 (time 20 min). A significant reduction in the anserine content was observed only when SV90 was used (time 10 min). The indicated heat treatment conditions resulted in a significant reduction in the carnosine content in the samples. In this study, a decrease in the content of anserine was determined for a sample of wet goose breast heated at 65 \({}^{\circ}\)C for 10 h (SV10), and an increase in the content of SV4, OV80 and OV90 was found, compared to raw meat. At the same time, in relation to dry matter, it was shown that sous vide samples had a lower anserine content compared to samples heated by steam in a combi-steamer oven. Taking into account the high solubility of anserine and relatively high thermal resistance indicated in the literature, it can be assumed that the reduction in anserine results from cooking loss. The cooking loss in the SV method was contained in a hermetic package, creating an extraction environment for further leaching of anserine, which was facilitated by the long processing time. In the OV, the cooking loss that formed did not have direct contact with the heated product. At the same time, the product was heated at a higher temperature, and the temperature gradient created on the surface could result in stronger denaturation of surface proteins, resulting in reduced mass transfer. This assumption is consistent with the findings of [PERSON] et al. [18], who indicated that microwave heating resulted in obtaining a surface layer on the meat that limited the losses of carnosine and anserine.