## 3 Results and Discussion
### Concentration of Sterol Oxidation Products in Food Products  
The content of cholesterol oxidation products in products of animal origin may be influenced by factors such as the temperature and processing time of the food product, as well as the method of storage. The content of oxysterols usually does not exceed 1% of the total cholesterol. However, there may be situations in which 10% or even more of the cholesterol present in a food product may be oxidized [17]. Figure 2 presents one of the chromatograms that were obtained during the separation of sterol and their oxidized forms. Figure 3 presents results regarding the content of sterol oxidation products in processed meat products. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Cereal Cakes** & **Powdered Milk** & **Biscuits** & **Sweet Desert Cakes** & **Chocolate Chip** & **Cookies** \\ \hline Cholesterol & 872 \(\pm\) 1.42 \({}^{\circ}\) & 266.96 \(\pm\) 82.55 \({}^{\text{b}}\) & 2007.11 \(\pm\) 167 57 \({}^{\text{a}}\) & 95.78 \(\pm\) 2.06 \({}^{\text{b}}\) & 46.26 \(\pm\) 2.19 \({}^{\circ}\) \\ Brassicasterol & 42.88 \(\pm\) 13.93 & n.d. & n.d. & n.d. & n.d. \\ Campesterol & 103.00 \(\pm\) 1.86 \({}^{\text{a}}\) & n.d. & 23.68 \(\pm\) 1.65 \({}^{\text{b}}\) & 12.03 \(\pm\) 0.83 \({}^{\text{c}}\) & 7.52 \(\pm\) 0.46 \({}^{\text{a}}\) \\ Stigmasterol & 7.74 \(\pm\) 0.34 \({}^{\text{a}}\) & n.d. & n.d. & 2.08 \(\pm\) 0.17 \({}^{\circ}\) & 6.82 \(\pm\) 0.29 \({}^{\text{a}}\) \\ \(\beta\) -sitosterol & 227.18 \(\pm\) 6.11 \({}^{\text{a}}\) & n.d. & 60.15 \(\pm\) 4.13 \({}^{\text{b}}\) & 43.01 \(\pm\) 3.4 \({}^{\text{c}}\) & 29.81 \(\pm\) 1.19 \({}^{\text{d}}\) \\ Avenasterol & n.d. & n.d. & n.d. & 3.65 \(\pm\) 0.28 \({}^{\text{a}}\) & 1.38 \(\pm\) 0.55 \({}^{\text{b}}\) \\ Sum of phytosterols & 380.8 \(\pm\) 22.24 \({}^{\text{a}}\) & n.d. & 83.83 \(\pm\) 5.78 \({}^{\text{b}}\) & 60.76 \(\pm\) 4.68 \({}^{\text{b}}\) & 45.53 \(\pm\) 2.49 \({}^{\text{c}}\) \\ \hline \hline \end{tabular} n.d.—not detected. \({}^{\text{a}\text{b}\text{c}}\)—values within a row with different letters are significantly different (\(p\leq\) 0.05).  
\end{table} 
Table 2: Content of sterols [mg/100 g of fat] in pastry products and powdered milk. Figure 2: Chromatogram after separation of sterols and oxysterol fraction extracted from steamed ban. Figure 3: (**a**) Content of sterol oxidation products [\(\mu\)g/g of fat] in meat products. (**b**) Content of sterol oxidation products [\(\mu\)g/g of fat] in meat products. (**a**–**e**–values within with different letters are significantly different (\(p\leq 0.05\)). The fat fraction of the tested products contained four oxysterols: 7\(\alpha\)-hydroxycholesterol, 7\(\beta\)-hydroxycholesterol, 7-ketocholesterol, and cholesterol triol. Their total content ranged from 0.58 ug/g of fat to 9.72 ug/g of fat (Figure 3a,b). A statistical analysis of the results concerning the total content of cholesterol oxidation products indicated that meat products can be divided into five homologous groups: the first group with the highest content of the above-mentioned compounds includes the product pork kabanos, the second group contains steamed bacon (Figure 3a,b), the third group includes salami, the fourth group contains canned pork, and the fifth group includes smoked bacon, pork kabanos and beef kabanos. The presence of cholesterol triol was detected only in three products: steamed bacon (3.24 ug/g fat), pork kabanos (4.73 ug/g fat), and beef kabanos (0.1 ug/g fat) (Figure 3a,b). The remaining oxysterols were determined in each of the analyzed products, with the highest content of 7\(\alpha\)-hydroxycholesterol in pork kabanos (4.56 ug/g fat) and the lowest in poultry kabanos (0.004 ug/g fat), beef kabanos (0.04 ug/g fat), salami (0.26 ug/g fat) and canned pork (0.16 ug/g fat). Salami contained 7\(\beta\)-hydroxycholesterol at a concentration of 1.65 ug/g of fat, while the lowest content of 7\(\beta\)-hydroxycholesterol was found in poultry kabanos (0.02 ug/g fat) and beef kabanos (0.05 ug/g fat).