Abstract
We've reported on a fluorescence measurement method for nondestructive evaluation of maturity degree in cherry tomato fruits before1). In this study, we tried to evaluate the maturity of large-fruited tomatoes such as Home-Momotaro instead of cherry tomatoes. Like as the previous paper1), we used Fluorescence Maturity Index (FMI) for the evaluation, which had been defined as log (F685/F740). Here, F685 and F740 are the fluorescence intensity of 685 nm and 740 nm respectively. From the results of fluorescence spectra measurements in various conditions, we found that the fluorescence detection from 45 degree to 60 degree angle by the 620 nm excitation is the best. In addition, transmission spectra measurements in fruits and fluorescence imaging on the fruits cross section were made. Because the F685 is reabsorbed by the chlorophyll in fruits, the FMI has increased along with the decrease of chlorophyll by ripening. Moreover, if distance between the excitation light irradiation point and the fluorescence detection point is fixed, the FMI would be able to evaluate the maturity degree in fruits of various sizes by the same scale. The most important finding is that, the FMI has a possibility to be able to detect the changes of maturity at the mature green stage of tomato fruits that can't be judged from visual observation.
