Soya beans are one of the most popular foods in Japan. But each year a small portion of the crop is infested with green, white or brown mold. Most factories use random sampling to detect spoiled beans, while others use visible spectroscopy or specific gravity testing.

A team of researchers from Osaka University in Japan has proposed a nondestructive inspection method for analyzing molds using three near-IR lasers for multispectral transmission imaging. By imaging the internal structure at three wavelengths and using a quantitative analysis method, they were able to determine the density of green mold distribution without destroying the bean. The group published its results in the April 20 issue of Applied Optics.