Spectrophotometric System for the Quality Evaluation of Unevenly Colored Food

Abstract

A spectrophotometric system was designed and constructed to measure nondestructively visible reflectance spectra, as well as fluorescence spectra, of unevenly colored food such as fruits and vegetables. It is in principle a single-beam spectrophotometer equipped with a large integrating sphere and operated with a microcomputer which controls wavelength scanning and data acquisition. The microcomputer provides also means of examining in detail relationship between color of reflected light or fluorescence of food and various quality factors, such as maturity, constituents, damage, deterioration and so on. For this purpose, several data processing subroutines are involved in the program; reflectance spectra, absorbance spectra, running-average, SAVITZKY-GOLAY'S smoothing, differential spectra, difference spectra, areas of spectral peaks, summation of spectra, parameters of several colorimetric systems, multiple regression analysis and so on. As examples of measurement, visible reflectance spectra of several fruits and vegetables and fluorescence spectra of mandarin orange whose peel oil has been out of oil cell ruptured with a needle are shown. The visible reflectance spectra demonstrate the effectiveness of the differential processing of the second order. The fluorescence spectra show the examples of difference spectra processing. The performance and drawbacks of the present system are discussed.