Possibility of Nondestructive Determination of Sugar Content, Acidity and Hardness of Plum Fruit by Near Infrared Spectroscopy

Abstract

Possibility of nondestructive determination of sugar content, acidity and hardness in 'Ooishi Wase' plum fruit by near infrared (NIR) spectroscopy was examined. Calibrations were constructed by stepwise multiple linear regression analysis using NIR absorbance value and sugar content, acidity or hardness. As a result, correlation coefficients between chemically analyzed data and NIR were 0.92 for brix, 0.78 for acidity and 0.83 for hardness, and standard errors of estimation were 0.41°Brix, 0.11% and 0.21kg, respectively. Standard errors of prediction were 0.61°Brix for brix, 0.19% for acidity and 0.21kg for hardness, suggesting that the NIR spectroscopy has possibility to determine sugar content and hardness except acidity in plum fruit. There is currently great interest in measurement of hardness of fruit by NIR spectroscopy.