# Quality Assessment of Banana Ripening Stages by Combining Analytical Methods and Image Analysis
## 3 Results and Discussion
### Physicochemical Parameters of the Banana Flesh during Storage  
The physicochemical parameters, including the water activity (aw), the moisture content (%), the Brix, the color, the texture, and the titratable acidity (%) of the banana-flesh samples were evaluated during the 21-day storage period, at 18.0 \(\pm\) 0.5 \({}^{\circ}\)C. The changes in \begin{table}
\begin{tabular}{c c} \hline \hline
**Days** & **Feature Mean Value 1** \\ \hline
2 & 26.778 \(\pm\) 6.226 a \\
4 & 41.498 \(\pm\) 13.915 b \\
7 & 57.879 \(\pm\) 14.781 c \\
9 & 79.789 \(\pm\) 17.804 d \\
11 & 84.432 \(\pm\) 20.755 d \\
14 & 107.475 \(\pm\) 22.436 e \\
17 & 110.277 \(\pm\) 18.991 e \\
21 & 130.263 \(\pm\) 17.983 f \\ \hline \hline \end{tabular} \({}^{\dagger}\) Results expressed as feature mean value \(\pm\) standard deviation (\(n=8\)). Different letters in the same column after each value indicate statistically significant differences (\(p<0.05\)), according to the Wilcoxon test.  
\end{table} 
Table 1: Variations of the feature mean values of the intensities of all the grayscale image pixels of the iodine-stained banana flesh, on days 2, 4, 7, 9, 11, 14, 17, 21 of storage. Figure 4: Colored images of the fruit ripening of the iodine-stained banana flesh during the 21-day storage period (i.e., days 2, 4, 7, 9, 11, 14, 17, 21). Figure 3: Scatter diagram of the discrimination, including textural features, amongst banana peel samples from days 2, 7, 11, and 21.  
the water activity, moisture (%), Brix (TSS), and titratable acidity (%) values of the samples on days 2, 4, 7, 9, 11, 14, 17, and 21 are shown in Figure 5.  
The water activity showed a statistically significant (\(p<0.05\)) variation between days 7 and 17 of storage, whereas the moisture content (%) showed a progressive increase during the 21-day storage period, which was especially significant at day 14 of the experiment. The Brix (TSS) values exhibited a significant (\(p<0.05\)) gradual increase until day 7 of storage, without further change until day 21 (the final day of storage). This agreed with [PERSON] et al. [28], who reported that commercial bananas of the _Musa_ varieties had reached a maximum TSS value at 9 days of storage, and this had then plateaued until the end of the storage period (14 days). Furthermore, it was reported that the parallel increase in the banana-flesh moisture and TSS values during ripening were the results of the hydrolysis of the starch into soluble sugars and the moisture migration from the peel to the flesh [12; 16; 29; 30]. The titratable acidity (%), which has been associated with the content of malic, oxalic, citric, and tartaric acids [2], presented significant (\(p<0.05\)) variations during storage, and we noted a maximum decrease at day 9 and a maximum increase at day 17. Significant variations in the titratable acidity (%) during ripening had been reported in many studies. Specifically, the malic acid had increased during ripening in [8; 31], whereas the oxalic acid had decreased in [32], causing an overall and significant increase in titratable acidity [33]. Figure 5: Water activity (aw), moisture content (%), Brix, and titratable acidity (%) of the banana-flesh samples during storage at 18.0 \(\pm\) 0.5 \({}^{\circ}\)C.  
The color parameters of the banana-flesh samples at days 2, 4, 7, 9, 11, 14, 17, and 21 are shown in Figure 6. The L* parameter of the banana flesh displayed a significant (\(p<0.05\)) reduction after day 4, and then increased until the day 17, followed by a significant decrease. The a* parameter showed a significant (\(p<0.05\)) increase up to day 9, and afterwards, decreased progressively until the final day of the storage period. The b* parameter demonstrated only insignificant fluctuations during the 21-day storage. Initially, the h parameter of the banana flesh presented a significant (\(p<0.05\)) reduction at day 7, then it stabilized until day 14, and finally, it increased at day 17.