## 3 Results and Discussion  
The basic quality indicators of poultry meat that determine its freshness and processing suitability are pH, water absorption, and meat colour. Our research showed that the duck meat used in the production of poultry burgers was of good quality and was not burdened with defects, as evidenced by the acidity of the breast muscles at the level of 5.80, water absorption at 33.07%, and colour component measured in the CIE L*a*b* system for lightness (L*) 41.79, for the intensity of red (a*) at the level of 5.80 [29; 30; 31; 32]. The degree of acidification of the duck meat burgers without the addition of turmeric (group I) was higher compared to the burgers with turmeric powder (group II and IV). Turmeric contains ascorbic acid and may affect the acidity level of products due to its presence [10; 11; 12; 13; 16; 17]. This may explain the lower pH of the duck burgers with turmeric paste and turmeric at the first evaluation date (Table 2). In the studies of [PERSON] et al. [33], the addition of turmeric to carabeef caused a decrease in the pH of the heat-treated meat product. Moreover, [PERSON] et al. [21] reported that increasing the addition of turmeric extract reduces the pH of the marinated poultry meat product. An indicator of the course of changes during the storage of meat in refrigerated conditions is the increase in the pH of the muscle tissue associated with the decomposition of lactic acid and the processes of protein proteolysis. The amino acids formed during this process are then broken down into ammonia and amines, which causes the meat to be alkalised [16]. In the authors' own research, in the control group (group I) and in the group with turmeric extract (group III), a significant increase in the pH value of the duck burgers was found after 6 days of refrigerated storage (Table 2), which may be associated with a lower ability to maintain free water [21]. A similar tendency was shown by [PERSON] et al. [33]. In the studies of [PERSON] et al. [17], a small addition of 0.1-0.3% turmeric powder did not change the pH of cooked beef meatballs. The results of the water absorption assay measured by the forced leakage method indicate that the addition of turmeric powder and paste had an effect on the water retention capacity of the product on the first day of refrigerated storage (Table 2). On the sixth day of the assessment, there was a reduction in water absorption in all groups, which was maintained until the end of the assessment. However, the smallest decrease took place in groups II and IV. It has been suggested that the addition of turmeric powder confers a protective effect against protein and lipid oxidation. Lipid content plays a key role in water retention and oxidative processes in both the lipid and protein fractions during storage and may alter the water-holding capacity of ground meat products [34]. [PERSON] et al. [16] showed that a 7-day storage time had an effect on weight loss and the amount of drip loss leakage of rabbit burgers with turmeric powder added. The studies of [PERSON] et al. [35] showed that the proportion of turmeric powder had a significant impact on the degree of the WHC parameter (%). The addition of 0.1-0.3% reduced the water absorption, while the addition of 0.5% turmeric powder maintained the water absorption at a level comparable to that of the control group.