Abstract

A new concept of spectral adjustment was examined to solve the problem of calibration transfer in a near infrared (NIR) sweetness sorting machine. Instead of pairing the absorbance values of each sample measured by master and slave instrument, the average spectrum of each instrument was used. Two identical NIR instruments, equipped with interactance fibre optics, were used as model instruments and a calibration equation for Brix determination of apples was developed as a model calibration. For each instrument, master and slave, each average spectrum was calculated from the spectra of an identical group of apples and then spectral matching of the slave instrument to the master was performed. The curve fitting method, either linear regression or polynomial, could not work well. However, by adding the difference spectrum, the differences of average absorbance values at wavelength i between the master and slave instruments, the spectrum of each sample measured by the slave instrument could successfully standardise the slave instrument. The matching was successfully done by adding the difference spectrum between the two average spectra to the slave instrument's spectra. It was found that the method could be used to compensate for both the wavelength shift and photometric change and it also proved that the method was applicable for both multiple linear regression and partial least squares equations.

© 2004 NIR Publications

Model transfer method based on piecewise direct standardization in laser-induced-breakdown spectroscopy

Ge Xie, Lanxiang Sun, Dong Shang, Yuan Gao, Xin Ling, and Xiuye Liu
Appl. Opt. 61(30) 9069-9077 (2022)

Nondestructive quantification of the soluble-solids content and the available acidity of apples by Fourier-transform near-infrared spectroscopy

Yibin Ying, Yande Liu, and Yang Tao
Appl. Opt. 44(25) 5224-5229 (2005)

Design of a simple non-destructive detection system using P-wave lasers for determining the soluble solids content of apples

Shih-Hao Hua, Chao-Pin Chen, and Pin Han
Appl. Opt. 56(22) 6235-6243 (2017)

Nondestructive determination of SSC in an apple by using a portable near-infrared spectroscopy system

Yizhe Zhang, Jipeng Huang, Qiulei Zhang, Jinwei Liu, Yanli Meng, and Yan Yu
Appl. Opt. 61(12) 3419-3428 (2022)

Accurate and nondestructive detection of apple brix and acidity based on visible and near-infrared spectroscopy

Yunqi Zhang, Yong Chen, Yun Wu, and Chaoyuan Cui
Appl. Opt. 60(13) 4021-4028 (2021)