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THE JOURNAL OF KMUTNB


Volume 32, No. 02, Month APRIL, Year 2022, Pages 332 - 341


A device for measuring apple sweetness using near infrared spectroscopy

Supachai Kulmutiwat และ Anupun Terdwongworakul


Abstract Download PDF

This research developed an apple sweetness measuring device without damaging the apple fruit by near-infrared absorbance measured in reflectance mode. The portable device was 23.6 cm wide, 35 cm long and 25 cm high. It consisted of a sample holder box, light source, spectrometer, reflectance carrying fiber optic, and controlling computer. In the development of the sweetness evaluation equation for coding in the controlling program, one hundred apples of Fuji cultivar were measured for near-infrared (NIR) absorbance in a wavelength range of 900 to 1700 nm and sweetness in terms of soluble solids content, which were used to develop the sweetness evaluating equation by partial least squares regression analysis. The performance of the equation for sweetness evaluation was achieved with a correlation coefficient (r) of 0.81 and root mean square error of prediction (RMSEP) of 0.69 °Brix. For testing the accuracy of the sweetness measuring device, the regression coefficients of the evaluation equation were coded as a part of the controlling program for sweetness evaluation. Apples purchased at a different time from those used in the equation development were tested by measuring the NIR absorbance on the device. The sweetness evaluation performance, comparing the evaluated sweetness and the reference sweetness showed accuracy with RMSEP of 0.75 °Brix. The sweetness measuring device based on NIR absorbance could be used to evaluate the sweetness of apple and show the sweetness result within 5 seconds.


Keywords

Sweetness; Non-Destructive Evaluation; Near Infrared Spectroscopy



THE JOURNAL OF KMUTNB


Published by : King Mongkut's University of Technology North Bangkok
Contributions welcome at : http://www.journal.kmutnb.ac.th