Abstract
To establish a nondestructive method of measuring astringency in peach fruit, near-infrared spectroscopy (NIRS) was attempted. In the organoleptic test, significant correlation existed between astringency and polyphenol concentration which ranged from 30 mg to 220 mg·100 g−1FW. Strong astringency was sensed when the polyphenol concentration in the fruit was higher than 110 mg·100 g−1FW. In analysis of the model solution of catechin and chlorogenic acid which are the main components of polyphenol in fruit using the second derivative transmittance spectra from 1100 nm to 2500 nm, it was found that there was a high correlation between absorbance around 1664 nm and 1730 nm and concentration of the solution. Then measurement of intact fruit by NIRS was performed using the second derivative reflectance spectra scanning from 1100 nm to 2500 nm. As a result of performing multiple regression analysis, the absorbance at 1720 nm showed high correlation with polyphenol. In the calibration equation development, the highest predicted correlation coefficient (r) was 0.80 and the bias-corrected standard error of prediction (SEP) was 14.7 mg·100 g−1FW for polyphenol. It can be concluded that NIRS is a promising method for determining the astringency of peach fruit.
