Determination of internal apple quality by non-destructive visible and near infrared spectroscopy


  • Moons, E. & Dardenne, P. (1999). Determination of internal apple quality by non-destructive visible and near infrared spectroscopy. Poster in: 9th International Conference on Near Infrared Spectroscopy (ICNIRS), Verona - Italy, 13-18/06/1999.
Type Poster
Year 1999
Title Determination of internal apple quality by non-destructive visible and near infrared spectroscopy
Event name 9th International Conference on Near Infrared Spectroscopy (ICNIRS)
Event location Verona - Italy
Label U15-0407
Recnumber 451
Event date 13-18/06/1999
Abstract There is a growing demand from the consumer for prime fruit quality. The consumer seems ready to pay a higher price for better tasty fruit of prime quality. Three major parameters have to be taken into account to determine the internal quality and taste of apple. These are hardness, sugar content and titrable acidity. At the present time, apple fruit grading is based only on the external aspect. Fruits are sorted visually and manually on the basis of size and colour which can be also considered as external indices of internal quality and at the same time, surface defects such as scabs, breaks, bruises, ... are detected. The goal of our study is to develop a grading machine which enables the classification of apples into different classes of composition and organoleptic quality. The NIR spectrometer used is a DA7000 from Perten Instruments. This postdispersive monochromator generates spectra from 400 to 1700 nm with a spectral resolution of 5 nm. The non destructive reflectance spectra are taken in four equidistant locations along the equator on the whole apples. They were measured during three years (1996-1998). The apples were selected among the main varieties found in Belgium and the entire range of variability was covered. The modified partial least square method (ISI, Infrasoft International) has been used to develop the models between the NIR spectra (math treatment 2,3,3,1) and the laboratory values. Based on 800 apples, the determination coefficients and the standard errors of prediction are respectively 0.88-0.49 for brix, 0.75-1.39 for titrable acidity, 0.84-0.78 for dry matter, 0.77-0.09 for pH, 0.67-0.83 for firmness, 0.80-0.20 for diameter. In order to satisfy the expectation of package storage houses and store markets, we are studying the on line application. The instrument is now installed above a belt conveyor. It should have an output of 3 apples per second. The high stability and the speed of the diode array instrument make it very suitable for on line measurements.
Author address Dardenne Pierre, Quality Department of Agro-food Products, Walloon Agricultural Research Centre (CRA-W), Chaussée de Namur, 24, B-5030 Gembloux, dardenne@cra.wallonie.be
Fichier U15-0407-dardenne-1999.jpg
Caption U15-0407-dardenne-1999.jpg
Authors Moons, E. & Dardenne, P.