AbstractThe determination of crude fiber in soybeans is a lengthy and time‐consuming procedure which requires extraction, digestion, and incineration and is not suitable as a routine processing‐control tool. A short control procedure has been developed, employing photomicroscopy, which is based on the characteristics of soybean hull cellulose to rotate plane‐polarized light. The sample is mounted on a microscope slide, treated with trichloro‐acetic acid, and placed in a polarizing projection microscope; the image is compared with a series of standard photomicrographs. The amount of hulls present in the sample is measured quantitatively, and an estimation is made on the crude fiber. The crude fiber estimation on de‐hulled soybeans can be made in 15 min compared with 8 to 12 hr by using the official crude fiber method.