# Quality Assessment of Banana Ripening Stages by Combining Analytical Methods and Image Analysis
## 1 Introduction  
The banana, a tropical fruit of the family _Musaceae_, belongs to the genus _Musa_, which is subdivided into _Rhodachlamus_, _Eumusa_, _Callimusa_, and _Australimusa_ sub-families, based on the number of chromosomes [1]. More widespread is the Eumusa species and, specifically, the edible varieties _Musa acuminate_ and _Musa balbisiana_[2]. Edible bananas are hybrid products of two wild diploid species, _Musa balbisiana_ Colla and _Musa acuminate_ Colla [2]. The duration of banana cultivation depends on its variety and the climatic conditions when the fruit is harvested at 8-13 months, having a mature green-colored peel [1]. The banana is considered a source rich in minerals, carbohydrates, dietary fibers, vitamins, and phenolic compounds, though its composition is based on the variety, growth stage and maturity [3]. In the first stages of the banana ripening progress, many of the typical biochemical, physicochemical, and organoleptic changes are, in general, positively characterized and accepted by consumers. As maturation proceeds and, in particular, when darkspots progressively appear on banana peel due to the enzymatic activity of the polyphenol and catechol oxidases, bananas gradually cease to meet the requirements for consumer acceptance and retail sale [4]. Therefore, the development and implementation of integrated tools and workflows for monitoring the progress of the banana ripening and reaching a desirable quality in terms of its organoleptic and physicochemical characteristics, especially by evaluating the fruit defects via non-destructive methods, is of utmost importance for marketability. Therefore, several studies [5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16] have been published regarding the assessment of the banana ripening progress that implemented various analytical methods and techniques, such as non-destructive and cost-efficient image-processing techniques (i.e., camera-based approaches) for peel color differentiation, electrical properties measurements, spectroscopic methods, scanning electron microscopy, texture analysis of peel and flesh, peel color measurement, starch-and-sugar content evaluation, and vitamins, organic acids, and chlorophyll determination. However, the application of a single or even a few of these methods and techniques has only provided information regarding specific characteristics of the fruit. For example, spectroscopic methods have yielded results for the bioactive content of the bananas while texture analysis has focused on the organoleptic attributes of the fruit, without examining its chemical composition. Furthermore, by simultaneously evaluating the various complementary results of several methods, including image analysis, physicochemical methods, and powerful statistical tools, such as discriminant analysis, could provide useful insights into the ripening progress of bananas. Therefore, the current research focused on the organoleptic and physicochemical properties of the bananas by evaluating the effect of storage time and conditions on banana shelf life. The main objective of this study was the assessment of the ripening progress of Cavendish bananas during storage, through the combined implementation of physicochemical, spectroscopic, and image-analysis methods, as well as the application of statistical tools. Specifically, water activity, moisture content, total soluble solids content, color parameters, texture attributes, and tittatable acidity (%) were measured. Moreover, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and image-analysis were also applied, and the comprehensive results from all methods were then comparatively studied in terms of ripening in controlled temperature and humidity during storage.