Observation and analysis of internal structure of cucumber fruit during storage using X-ray computed tomography

In this study, X-ray computed tomography (CT) was used as a non-destructive technique to characterize and quantify the internal structure of cucumber fruit during storage. The physical properties of cucumber fruit were also measured destructively and related to X-ray absorptivity, and also changes in three-dimensional heterogeneous internal structure were visualized during storage at 15 °C and 25 °C and 90% RH for 7 days. As a result, the average gray scale (GS) value calculated from X-ray CT scanned tissue images indicated good correlations with the density, porosity, and elastic modulus of cucumber fruit. The peak height of the GS value related to the density and porosity. Standard deviation of the GS value was also related to the moisture content of the fruit. These results indicated that X-ray CT can be used to estimate physical properties related fruit quality. It was also revealed that the radiodensity of cucumber fruit changed in the mesocarp tissue but not change in the placenta tissue. GS level in the mesocarp tissue changed from white to dark from the fruit pedicel towards the apex at 25 °C. This result is useful to understand the expansion of low density part in fruit during storage.