# Quality Assessment of Banana Ripening Stages by Combining Analytical Methods and Image Analysis
## 4 Conclusions  
In the present study, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, texture, colorimetric, physicochemical, and digital-image analysis methods were synergistically applied to pinpoint the effect of ripening on the chemical and physical characteristics of banana peels and flesh during storage in controlled temperatures. The most interesting findings are summarized below. Concerning the banana peel, the ripening progress resulted in an increase in the peel redness, a decrease in its luminosity, peel conversion from yellow to dark blue, an increase in gray-level inequality, and the non-uniformity of image-texture structures. The combination of the computed image-texture features of the banana peel enabled a highly accurate classification of the banana samples according to 4 ripening stages (day 2, day 7, day 11, and day 21) during the storage period. Regarding the banana flesh, day 7 and day 11 were of particular interest because from these days onwards, significant changes in the flesh composition were revealed, as reflected by the physicochemical parameters and the FTIR spectral interpretation. Therefore, the ripening progress resulted in a consistent increase in the moisture content and the total soluble solids (Brix) until day 7 and a drastic decrease in all texture attributes mainly from day 7 onwards. Furthermore, all the FTIR spectra intensities, which were related to the presence of starch (i.e., amylose and amylopectin), displayed a dramatic decrease, or disappeared completely, from day 7 onwards, whereas the intensities related to the presence of sucrose and fructose showed a significant increase from day 7 onwards. Moreover, the intensities related to the moisture content exhibited a significant increase from day 11 onwards. In accordance with the FTIR findings, the iodine testing on the flesh slices demonstrated an increase directly related to the breakdown of starch into sugar and the consequential destruction of the amylose-iodine complex. Based on the correlations between the peel image analysis and the flesh physicochemical parameters, the redness and yellowness of the banana peels were strongly correlated with storage time, whereas the moisture content, the texture attributes, and the total soluble solids (Brix) revealed that the alterations in the color parameters of the banana peels were positively or negatively related to the variations in the composition and texture of the banana flesh. In conclusion, the monitoring of banana ripening using physicochemical parameters is important for ensuring consistent quality. For this purpose, various techniques such as image analysis, color analysis, texture analysis, and chemical analysis can be implemented. Assessing the variations of the aforementioned parameters during banana ripening could optimize the storage and transport of bananas. Moreover, the results of the current study highlighted an essential complementary tool for evaluating banana-ripening progress, with potential applications for other fruits and vegetables. However, similar to other studies concerning the fruit-ripening process, there were limitations and knowledge gaps that should be considered. For example, the evaluation of the banana ripening process was strongly dependent on the type of device used for image analysis (i.e., digital cameras vs. smartphones vs. electronic noses). In addition, more bananas species (i.e., red bananas, etc.) should be included in future studies, and additional statistical tools, such as machine- and deep-learning methods, should be evaluated for classifying the ripening stages of bananas and other fruits.