# Changes in Quality Features of Pork Burgers Prepared with Chokeberry Pomace During Storage
## 3 Results and Discussion
### pH Value of Pork Burgers During Storage  
The average pH value of the pork burgers varied from 6.73 in the B5 product on day 7 to 6.93 in the BC product on day 1 (Table 2). It was found that both product treatment (i.e., the addition level of black chokeberry pomace) and storage time significantly affected (\(p<0.05\)) the pH value of pork burgers. However, no interaction (\(p>0.05\)) was observed between the treatment and storage time (Table 2). It was found that incorporating chokeberry pomace into burgers resulted in a significant (\(p<0.05\)) reduction in pH, regardless of storage time. The product without chokeberry pomace (BC) had the highest pH (\(p<0.05\)) across all storage times, measuring 6.93 on day 1 and 6.90 on day 14. The results indicated that even the smallest amount of chokeberry pomace (B2) led to a relatively small but significant (\(p<0.05\)) pH decrease compared to the BC product. Pork burgers (B2) with 2% chokeberry pomace had a significantly lower pH than the control product (BC) throughout the storage period. Increasing the addition of chokeberry pomace to 3.5% and 5% (B3.5 and B5, respectively) further reduced the pH. The lowest pH was recorded in the B5 product, ranging from 6.75 on day 1 to 6.74 on day 14. The B5 product had a significantly (\(p<0.05\)) lower pH than the BC and B2 products, regardless of storage time. During the 14-day storage period, pH decreased only slightly in each product treatment, with the observed changes being insignificant (\(p>0.05\); Table 1). The variations in pH during storage were minimal, reaching a maximum of 0.03 units for BC and B2 products. The pH values of pork burgers with different levels of added chokeberry pomace were likely influenced by the active acidity of the raw materials and their proportions in the recipe. The average pH of the raw materials used in burger production was 6.03 for pork ham, 6.08 for pork jowl, and 3.36 for chokeberry pomace. Based on this, incorporating chokeberry pomace into the meat batter is expected to lower the burger's pH. Additionally, the slight pH decrease observed on day 14 of storage may be attributed to lactic acid bacteria growth, which will be discussed later in the article. The results of this study align with those of other researchers [14; 16; 45], who demonstrated that including a plant ingredient, even in processed form, in a meat product formulation can reduce active acidity. In contrast, other researchers [17; 44] reported that fruit or vegetable pomace in processed forms did not significantly alter the pH of meat products. For instance, raw pork burgers containing an alcoholic extract from red grape pomace (0.06 g per 100 g final product) and stored under aerobic conditions showed no significant difference (\(p>0.05\)) in active acidity compared to the control product over six days [17]. Similarly, dried tomato pomace at levels ranging from 0% to 7% (w/w) had no effect (\(p>0.05\)) on the pH of beef sausages [44]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Storage Time [Days]** & **BC *** & **B2 *** & **B3.5 *** & **B5 *** \\ \hline
1 & 6.93 \({}^{e}\)\(\pm\) 0.02 & 6.82 \({}^{d}\)\(\pm\) 0.01 & 6.77 \({}^{abc}\)\(\pm\) 0.01 & 6.75 \({}^{ab}\)\(\pm\) 0.01 \\
7 & 6.91 \({}^{e}\)\(\pm\) 0.01 & 6.80 \({}^{cd}\)\(\pm\) 0.00 & 6.76 \({}^{ab}\)\(\pm\) 0.01 & 6.73 \({}^{a}\)\(\pm\) 0.00 \\
14 & 6.90 \({}^{e}\)\(\pm\) 0.01 & 6.79 \({}^{bcd}\)\(\pm\) 0.01 & 6.76 \({}^{ab}\)\(\pm\) 0.01 & 6.74 \({}^{a}\)\(\pm\) 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Changes in pH value (\(n=12\)) in pork burgers with added black chokeberry pomace during storage (mean value \(\pm\) standard deviation). \(L^{\star}\), \(a^{\star}\), and \(b^{\star}\) Color Parameters of Pork Burgers During Storage  
Table 3 presents the results of instrumental measurement of color parameters (L*, a*, and b*) of pork burgers differing in the amount of black chokeberry pomace added.