Nondestructive evaluation of rice using two-dimensional imaging of photoluminescence

Evaluation technique of rice using photoluminescence (PL) imaging has been developed based on the visible light PL with broad peak at a wavelength of λ=462 nm from starchy foods under illumination of ultraviolet (UV) light at λ=365 nm. Peak intensity of PL varies with variety and source of the rice. Two-dimensional (2D) images of PL from rice reveal the uniformity of the rice product. Blended rice from different species can be detected using 2D PL image. Brightness over the 2D PL images of rice with a single breed from a single source distributes according to a Gaussian distribution curve. Deviation from a Gaussian distribution curve estimated as χ² value and correlation coefficient increases in a rice specimen of various species of blended rice. Image processing of PL images from specimens reveals contamination and/or mixing of other species or foreign objects. A 2D PL imaging technique is potentially useful for nondestructive and quick evaluation and quality control of the rice products.