Abstract
Color is one of the key sensory characteristics in the evaluation of the quality of mangos (Mangifera indica) especially with regard to determining the optimal level of ripeness. However, an objective color determination of entire fruits can be a challenging task. Conventional evaluation methods such as colorimetric or spectrophotometric procedures are primarily limited to a homogenous distribution of the color. Accordingly, a direct assessment of the mango quality with regard to color requires more pronounced color determination procedures. In this study, the color of the peel and the pulp of the mango cultivars “Nam Dokmai”, “Mahachanok”, and “Kent” was evaluated and categorized into various levels of ripeness using a charge-coupled device (CCD) camera in combination with a computer vision system and color standards. The color evaluation process is based on a transformation of the RGB (red, green, and blue) color space values into the HSI (hue, saturation, and intensity) color system and the Natural Color Standard (NCS). The results showed that for pulp color codes, 0560-Y20R and 0560-Y40R can be used as appropriate indicators for the ripeness of the cultivars “Nam Dokmai” and “Mahachanok”. The peels of these two mango cultivars present two distinct colors (1050-Y40R and 1060-Y40R), which can be used to determine the fruit maturity during the post-ripening process. However, in the case of the cultivar “Kent”, peel color detection was not an applicable approach for determining ripeness; thus, the determination of the pulp color with the color code 0550-Y20R gave promising results.
Highlights
Color is an important factor for the quality assessment of fresh produce, as it can be used to estimate the ripeness of fruits and vegetables
The results showed that for pulp color codes, 0560-Y20R and 0560-Y40R can be used as appropriate indicators for the ripeness of the cultivars “Nam Dokmai” and “Mahachanok”
This study focused on the automated color measurement of mango peel and pulp using a computer vision system and color standards
Summary
Color is an important factor for the quality assessment of fresh produce, as it can be used to estimate the ripeness of fruits and vegetables. According to Nagle et al (2016), chlorophylls, carotenoids, and anthocyanins are responsible for the green, yellow, and red colors of fruit and vegetables, respectively, representing the key pigments in mango (Mangifera indica) maturation [4]. Mangos are regarded as fully ripe when they change to a juicy and soft texture, with a sweet taste and rich aroma, and fully developed coloring depending on cultivars [7]. This behavior can be found in many other (climacteric) fruits, such as blueberries, where color significantly changes from slightly green to deep purple tones [8]. Spectrophotometry is a technique widely used to determine produce color by measuring the spectral distribution of transmittance using a sample’s reflection [9]
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