Non-destructive measurement of rice amylose content using near-infrared spectroscopy for application at grain elevators and milling plants

Accurate measurement of rice amylose content, defined as the percentage of amylose in the total starch content of the rice endosperm, is crucial for determining its taste and quality, but can prove challenging for rice-grain elevators and milling plants. We therefor investigated the potential of a newly developed near-infrared (NIR) spectrometer to provide reliable and accurate measurements of the rice amylose content in a total of 868 samples of 14 rice varieties collected in Hokkaido, Japan, between 2013 and 2021. Calibration models to determine rice amylose content are developed using the NIR spectrometer. The models are created by mapping the NIR spectra and amylose content of rice samples collected between 2013 and 2018 using a moving-window partial least squares regression algorithm. The accuracy of the calibration models is validated using rice samples with an unknown amylose content collected between 2019 and 2021. The coefficient of determination between the NIR-predicted and chemically measured amylose contents (> 0.96) and the standard error of prediction (0.4–0.5%) validate the accuracy, stability, and robustness of the calibration models for application in rice grain elevators and milling plants. The NIR technique can screen high-quality rice to improve its quality and increase its value. This technology is currently being applied to rice grain elevators and milling plants in Hokkaido and will soon be implemented throughout Japan.