RGB imaging system for monitoring quality changes of seedless watermelon during storage

Watermelons (Citrullus lanatus) are considered as one of the popular tropical fruits which contain high nutritional values. As quality has become the main concern in recent years, it is crucial to preserve the fresh produce of watermelons and determine the quality accurately. In this study, the potential of RGB imaging system was evaluated to determine the seedless watermelon properties such as firmness, soluble solids contents (SSC), moisture content, and color (L*, a*, b*) during storage. The properties were measured every three days intervals within 21 days of storage using CCD camera, penetrometer, refractometer, pH meter, colorimeter and digital balance. The acquired images were analyzed based on the feature extraction and the RGB color space obtained from the images that were correlated with the quality changes of the fruit. The prediction models were developed by using partial least square (PLS) regression. The PLS prediction models obtained the correlation coefficient (r) values of 0.81, 0.80, 0.78, 0.56, 0.61, 0.44, and 0.82 for firmness, SSC, pH, moisture content, L*, a*, and b*, respectively. Thus, RGB imaging technique has a great perspective to be used for monitoring the quality changes of seedless watermelon during storage and postharvest handling.