## 3 Results and Discussion
### HPLC Analysis of Real Samples
#### 3.7.2 Analysis of Food Samples  
Food samples were prepared according to the previously described protocol (Section 2.7) and MSM protocol for lutein extraction. HPLC analysis of food samples was performed according to the previously described protocol for Chromatographic Procedure (Section 2.3). The percentages of moisture in food samples calculated after drying are shown in Table 5. The concentration of lutein in fresh samples (FW) in our study was calculated based on the percentage of moisture in the sample. Concentrations of lutein obtained from food samples in our investigation and previously conducted investigations are shown in Table 6. The highest lutein concentration was determined in parsley leaves (1581.489 mg/kg), and the lowest was found in wheat flour (4.737 mg/kg). Significantly higher lutein concentrations were found in samples of parsley leaves, lettuce, and kale (_p_ < 0.001) compared to other food samples. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Composition** & **mg of Lutein/kg of** \\  & & **Feed Mixture** \\ \hline
1 & standard hens’ feed mixture & 41.732 \(\pm\) 0.63  \\ \hline
2 & Premix * & 8.482 \(\pm\) 0.56  \\ \hline
3 & standard hens’ feed mixture with the & 40.181 \(\pm\) 1.16  \\  & addition of corn & 40.181 \(\pm\) 1.16  \\ \hline
4 & ground corn and Premix * mixed in a ratio & 35.828 \(\pm\) 0.67  \\  & of 4:1 & \\ \hline
5 & standard hens’ feed mixture mixed with & 35.161 \(\pm\) 0.61  \\  & ground corn, barley, and soy & 35.161 \(\pm\) 0.61  \\ \hline
6 & standard hens’ feed mixture mixed with & \\  & ground corn, oats, and wheat & 3.483 \(\pm\) 1.70  \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Composition of analyzed hens’ feed mixtures and obtained concentrations of lutein (\(\overline{x}\) \(\pm\) sd). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{2}{c}{**Sample**} & \multicolumn{2}{c}{**Previously Conducted Investigations**} & \multicolumn{2}{c}{**Our Investigation**} \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & **mg/kg of \({}^{\ast}\) DW** & **mg/kg of \({}^{\ast\ast}\) FW** & **Reference** & **mg/kg of \({}^{\ast}\) DW** & **mg/kg of \({}^{\ast\ast}\) FW** \\ \hline \hline \multirow{4}{*}{lettuce} & & 5.58–13.38 & 46 & \multirow{4}{*}{1179.246 \(\pm\) 98.40 b  } & 67.229 \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 176.9–754.5 & & 47 & \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 3160 & & 48 & \\ \hline \hline \multirow{4}{*}{kale} & & 71.58–100.05 & 49 & \multirow{4}{*}{15.7362} \\ \cline{2-5} \cline{5-5} \cline{5-5} \multicolumn{1}{c}{} & 50.6 & 50 & & \\ \cline{2-5} \cline{5-5} \cline{5-5} \multicolumn{1}{c}{} & 15.1 & 51 & & \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 441.44 & 619.37 & 52 & \multirow{4}{*}{173.62} \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 660–2530 & & & \\ \hline \hline \multirow{4}{*}{carrot} & & 0.830–1.665 & 54 & \multirow{4}{*}{15.99} \\ \cline{2-5} \cline{5-5} \cline{5-5} \multicolumn{1}{c}{} & 22.3 & 52 & & \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 4.9–15.2 & 55 & & \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 57.58 & & & \\ \hline \hline \multirow{2}{*}{butternut squash} & & 16.8 & 57 & \multirow{2}{*}{49.234 \(\pm\) 2.95 e  } & 3.592 \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 383.98 & 52 & & \\ \hline \hline \multirow{2}{*}{parsley leaves} & 413.0 & & 58 & \multirow{2}{*}{1581.489 \(\pm\) 124.82 a  } & 287.125 \\ \cline{2-5} \cline{5-5} \multicolumn{1}{c}{} & 80.52 & 60 & & \\ \hline \hline \multirow{4}{*}{paprika spice} & 55.0–61.4 & & 61 & \multirow{4}{*}{-} \\ \cline{2-5} \cline{  
The concentration of lutein in various samples depends on the cultivar and the production system used, which is the reason for the wide range of determined concentrations. Table 6 presents data obtained from previously conducted investigations. Lettuce is a vegetable known for its benefits to human health, largely due to the various bioactive compounds it contains. One of the primary carotenoids in lettuce is lutein [50]. [PERSON] et al.