Nondestructive evaluation of the changes of total flavonoid, total phenols, ABTS and DPPH radical scavenging activities, and sugars during mulberry (Morus alba L.) fruits development by chlorophyll fluorescence and RGB intensity values

The use of chlorophyll fluorescence measurements and RGB intensity values to noninvasively evaluate changes of the internal chemical parameters (total flavonoid, total phenols, ABTS cation and DPPH radical scavenging activities and sugars) was investigated during all the development stages (ST) and the last four development stages of mulberry fruits in this study. The appropriately fitted relationships in this study revealed that chlorophyll fluorescence and RGB intensity have high correlations with the internal chemical parameters of mulberry fruits. Especially, each of the internal chemical parameters has higher correlations with chlorophyll fluorescence and RGB intensity during the period of ST4-ST7 than during the period of ST1-ST7 respectively. High correlations between chlorophyll fluorescence and the internal chemical parameters were found during the period of ST4-ST7, with R2 ranged from 0.82 to 0.94. RGB intensity values showed fine correlations with the internal chemical parameters with R2 ranged from 0.93 to 0.97 during the period of ST4-ST7. Therefore, chlorophyll fluorescence and RGB intensity values may be potential methods for quality evaluation of mulberry fruits during development, however, it is of great importance to select the most adequate parameter for the evaluation of different chemical components.

► Fluorescence and RGB were used to evaluate chemical components noninvasively. ► RGB could estimate chemical components well. ► Fv showed a best correlation with fructose and glucose respectively. ► Fluorescence combined with RGB could evaluate the quality perfectly.