Determination of Sugar Content in Intact Peaches by Near Infrared Spectroscopy with Fiber Optics in Interactance Mode.

Abstract

To develop a nondestructive sugar analyzer for intact peaches, the potential of the near infrared (NIR) method with fiber optics in interactance mode was evaluated. In 'Shimizu Hakuto', a white peach cultiver, there were clear differences among the NIR second derivative spectra of high, medium, and low Brix values in the wavelength region around 906 nm. This wavelength was assined to sucrose and selected as first wavelength. The highest multiple correlation coefficient of 0.97 was obtained in the linear regression equation equation that included four optical terms of d2log(1/R) at 906, 878, 870 and 889 nm, while a standard error of calibration (SEC) was 0.48 oBrix. A bias-corrected standard error of prediction (SEP) was 0.50 oBrix with a bias of 0.01 oBrix, suggesting that the NIR method is sufficiently accurate to determine sugar content in intact peaches to be practical.