[Research on nondestructive measurement of soluble tannin content of astringent persimmon using visible and near infrared diffuse reflection spectroscopy].

The objectives of the present study were to establish the relationships of the visible and near infrared diffuse reflection (Vis/NIR) spectroscopy and the soluble tannin content of internal quality index of astringent persimmon, and to evaluate the value of Vis/NIR spectroscopy in measuring the soluble tannin content of internal quality index of astringent persimmon. In the spectral region between 570 and 1 848 nm, calibration results for the soluble tannin content of astringent persimmon were compared with different regression techniques, different derivative treatments and different scatter and standard treatments. The results showed that the modified partial least squares(MPLS) model, with respect to the first derivative D1 log(1/R) and detrend only, provided better prediction performance for the soluble tannin content of astringent persimmon fruit, with the correlation coefficient of cross validation of calibration (R(cv)) and correlation coefficient of prediction (R(p2)), the root mean square error of cross validation of calibration (RMSECV) and the root mean square error of prediction (RMSEP) of 0.722 7, 0.678 5, 0.148, and 0.176 3 respectively. The preliminary research on the built models indicated that nondestructive measurement of the soluble tannin content of astringent persimmon using Vis/NIR spectroscopy technique was feasible, but the precision of the models could be improved further.