Objects are sorted according to specific gravity by illuminating the objects with near-infrared light with different wavelengths. Measurement of the light absorbed by each object at the different wavelengths permits a dry matter content of the object to be determined. Specific gravity can then be determined using a predetermined correlation between dry matter content and specific gravity. A sorting mechanism responsive to determination of specific gravity by the controller separates the food objects into at least two different groups corresponding to different specific gravity.