# Application of Digital Image Analysis for Assessment of Star Content and Distribution in Potatoes
## 3 Results and Discussion  
The results of the ANOVA of the starch content in relation to the potato variety (Table 2) allowed us to distinguish three homogeneous groups: potatoes with a low (Gala, Lord, Melody), medium (Lilly), and high starch content (Satina and Allianz). The starch content assessment with the polarimetric method did not enable us to distinguish between individual varieties. The starch contents significantly differ between the frozen and the cold-stored potatoes (Table 3), but the differences are smaller than the differences between the cultivars, so it does not make it possible to unambiguously distinguish the potatoes stored in a freezer. The decrease in the starch contents of frozen potatoes is linked with the starch degradation to simpler sugars and is the plant's protective mechanism in response to freezing [22; 23]. At the same time, water is detached from the starch at low temperatures, leading to its retrogradation [24; 25; 26]. The results of the ANOVA of the basic statistics of pixel brightness in relation to potato variety (Table 4), allowed us to distinguish only three groups of cultivars, very much like in the case of the chemical analysis of the starch content. The mean values and medians are significantly negatively correlated with the total starch contents of the potatoes because the values similar to 255 denote light-colored areas, \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Potato** & **Mean** & **Median** & **Range** & **Skewness** &
\begin{tabular}{c} **Coefficient** \\ **of Variation** \\ \end{tabular} \\ \hline Gala & 68.2 \({}^{\text{a}}\) & 68.0 \({}^{\text{a}}\) & 53.7 \({}^{\text{a}}\) & 0.29 \({}^{\text{abc}}\) & 42.4 \({}^{\text{a}}\) \\ Lord & 62.5 \({}^{\text{ab}}\) & 62.1 \({}^{\text{ac}}\) & 51.9 \({}^{\text{a}}\) & 0.36 \({}^{\text{c}}\) & 28.4 \({}^{\text{b}}\) \\ Melody & 54.8 \({}^{\text{b}}\) & 54.4 \({}^{\text{c}}\) & 59.8 \({}^{\text{a}}\) & 0.18 \({}^{\text{d}}\) & 19.0 \({}^{\text{c}}\) \\ Lilly & 58.1 \({}^{\text{b}}\) & 57.6 \({}^{\text{c}}\) & 63.2 \({}^{\text{a}}\) & 0.26 \({}^{\text{ab}}\) & 25.1 \({}^{\text{d}}\) \\ Satina & 44.3 \({}^{\text{c}}\) & 43.6 \({}^{\text{b}}\) & 61.3 \({}^{\text{a}}\) & 0.32 \({}^{\text{bc}}\) & 26.4 \({}^{\text{e}}\) \\ Allianz & 43.9 \({}^{\text{c}}\) & 43.0 \({}^{\text{b}}\) & 61.7 \({}^{\text{a}}\) & 0.21 \({}^{\text{ad}}\) & 26.9 \({}^{\text{e}}\) \\ \hline LSD value & 8.7 & 8.3 & 17.4 & 0.07 & 1.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Values of basic statistics of pixel distribution along the measurement lines in cold-stored potatoes, depending on potato cultivar (homogeneous groups are labeled with the letters). \begin{table}
\begin{tabular}{c c} \hline \hline
**Potato Cultivar** & **Starch Content [\%]** \\ \hline Gala & 11.7 \({}^{\text{a}}\) \\ Lord & 12.5 \({}^{\text{a}}\) \\ Melody & 12.6 \({}^{\text{a}}\) \\ Lilly & 14.2 \({}^{\text{b}}\) \\ Satina & 17.7 \({}^{\text{c}}\) \\ Allianz & 17.9 \({}^{\text{c}}\) \\ \hline LSD value & 1.09 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Starch contents of cold-stored potatoes of 6 cultivars assessed chemically (homogeneous groups are labeled with the letters). \begin{table}
\begin{tabular}{c c} \hline \hline
**Storage** & **Starch Content [\%]** \\ \hline Cold store: 4 \({}^{\text{c}}\)C & 14.9 \({}^{\text{a}}\) \\ Freezing: \(-15\,{}^{\text{c}}\)C & 14.0 \({}^{\text{b}}\) \\ \hline LSD value & 0.64 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Starch contents of frozen and cold-stored potatoes, assessed chemically (homogeneous groups are labeled with the letters). which are not stained with iodine (lack of starch), while values close to 0 denote dark areas, i.e., starch granules stained with iodine. The starch contents of the potatoes vary from 10% to 20% and depend on the potato variety, but they do not enable precise distinguishing between the cultivars as in the work of [PERSON] et al., 2014, which compared the starch contents of different apple varieties using ImageJ [27].