近赤外分光法によるモモ果実の渋味の評価(発育制御)  [in Japanese] Distinction of Astringency in Peach Fruit Using Near-Infrared Spectroscopy(Postharvest Physiology & Technology)  [in Japanese]

モモ果実の渋味の近赤外分光法による非破壊測定の方法について検討した.モモの渋味は果肉中の全ポリフェノール濃度と相関が高く,全ポリフェノール濃度が100g当たり約110mg以上で強い渋味を感じた.そこで,モモ果実中の全ポリフェノール濃度の推定を400〜1100nmの反射スペクトルから試みたが,誤差が大きく測定不可能と考えられた.しかし,モモのポリフェノールの主要な構成成分であるカテキンとクロロゲン酸水溶液の1100〜2500nmの透過スペクトルを解析すると,1664nmと1730nm付近に相関の高い波長域が存在した.そこで,モモ果実の1100〜2500nmの反射スペクトルによる解析を行ったところ,1720nm付近に全ポリフェノール濃度と相関の高い波長域が存在し,重回帰分析による全ポリフェノール濃度の推定精度はSEP=14.7mg・100g^<-1>FWと比較的高かった.これらの結果から1100〜2500nmの反射スペクトルを測定することによって,モモ果実の渋味を非破壊的に判別できる可能性が高いと考えられた.

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 30mg to 220mg・100g^<-1>FW. Strong astringency was sensed when the polyphenol concentration in the fruit was higher than 110mg・100g^<-1>FW. 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 1100nm to 2500nm, it was found that there was a high correlation between absorbance around 1664nm and 1730nm and concentration of the solution. Then measurement of intact fruit by NIRS was performed using the second derivative reflectance spectra scanning from 1100nm to 2500nm. As a result of performing multiple regression analysis, the absorbance at 1720nm 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 14.7mg・100g^<-1>FW for polyphenol. It can be concluded that NIRS is a promising method for determining the astringency of peach fruit.