Estimation of maturity-related quality of edamame based on features of color and fluorescence images

Abstract

The optimal harvest timing of edamame is short, and evaluation of maturity-related quality is important in determining the optimal harvest timing. This study aimed to estimate the maturity-related quality of edamame based on the fluorescence characteristics of pod surface. Excitation emission matrix (EEM) measurements were conducted, and color images and fluorescence images under 365 nm excitation were taken in edamame at different harvest days. Water content and sugar content were measured as maturity- related qualities. Then, estimation by partial least squares regression (PLSR) was performed using the color and texture features of the color and fluorescence images. When using color features alone, the addition of fluorescence image features improved estimation accuracy. Further incorporation of texture features improved the accuracy, achieving R²_CV=0.526 and RMSE_CV=2.23% for water content and R²_CV=0.532 and RMSE_CV=0.221 g/100 g DW for fructose content, respectively. These results indicate the potential of fluorescence characteristics and texture features in estimating maturity-related quality of edamame.