## 3 Results and Discussion
### MATLAB Treatment  
Figure 3c,d present the scans, after eight days, of a sample protected with green tea combined with \(\alpha\)-tocopherol (A2) and a blank sample (B), respectively. The segmentation of these mushrooms is shown in Figure 3e,f. The colour white indicates the analysed sample. The gill areas were discarded to avoid falsification of results. Non-zero values of \(y\) were obtained for the following \(x\)-values: 6, 22, 23, 27, 43, 44, 48 and 64. Values of \(y\) corresponding to \(x\) = 6 and \(x\) = 64 were rejected during optimization of the process, so they were not used in PCA. In loading plots, the most important influencing variables are located along the horizontal axis. In this case, a loading plot can be used as a screening tool for choosing relevant variables. Figure 4 shows the oxidation pattern created using all blank samples. The samples were coded according to the format X_m_n, where \"X\" is the kind of sample (B, A1, A2, A3), \"m\" is the sample age in days and \"n\" is the replicate number. The model used described 66% of the accumulated variance. Grouping of samples of the same type can be observed with some exceptions. The samples marked with an asterisk should belong to other groups. Our method classified correctly up to 90% of blank samples according to their age. Minkrooms are not uniform samples (compared within themselves) in terms of surface colour. Moreover, each sample can undergo a distinct process of oxidation over time. When working with real natural foodstuffs, one must keep in mind that several differences in the obtained oxidation pattern are typical and expected. The influence of three different antioxidants on extending the shelf life of mushrooms was evaluated. According to the results obtained in our previous work [8], antioxidants A1 and A2 should influence the analysed samples positively. These \"positive\" antioxidants were chosen to confirm that the developed method was working correctly. Moreover, one \"negative\" antioxidant (A3) was used to check the data distribution in an active agent that was previously proven ineffective. Figure 5 shows the distribution of samples A1, A2 and A3 on the background of the oxidation pattern. Sample A1\(8\)10 was rejected because it was found totally outside the oxidation pattern, preventing the correct distribution of the other samples. It can be seen that 8-day samples treated with antioxidant A1 are placed between 1 and 4 days of samples B without antioxidant protection, and 100% of the mushrooms treated with sodium metabisulphite were found to be fresher than their corresponding blanks. To specify, among them, 33% of the samples behaved as one-day blank samples, and 67% acted as 4-day blank samples. The distribution of samples A2 shows that they are mainly \begin{table}
\begin{tabular}{c c c} \hline \hline \(\mathbf{N}^{\circ}\) &
\begin{tabular}{c} **Compared Pair (Day 8)** \\ **(\(\alpha\) = 0.05) Limit \(\geq\) 27 \({}^{\text{a}}\)** \\ \end{tabular} & **Votes** \\ \hline \hline \multirow{2}{*}{1} & B & 13 \\  & A1 & 27 \\  & B & 14 \\  & A2 & 26 \\  & B & 30 \\  & A3 & 10 \\ \hline \hline \end{tabular} \({}^{\text{a}}\) Samples with 27 or more votes are significantly different from the other one.  
\end{table} 
Table 3: Results of the visual panel for samples with different antioxidant treatments. located in the 4-day group of blanks. This means that the tested antioxidants extended the shelf life of mushrooms by keeping their surface appearance fresher than the corresponding unprotected samples; 70% of the mushrooms treated with green tea were detected to be fresher than their corresponding blanks. Among them, 10% of the samples were found in the 1-day group, and 60% of the samples were found in the 4-day group. Moreover, the active agents used had different ways of action. The first one, A1, was volatile, and theoretically, it should have a strong influence on the samples. The second  
Figure 4: Oxidation pattern corresponding to all blank samples by means of principal component analysis (PCA).