Abstract: A sorting machine for sorting ground nuts affected by a mould which produces aflatoxin comprises detectors for detecting infra-red (or red) and green light respectively reflected from a ground nut being viewed. The infra-red detector produces a first signal indicative of the amount of mould carried by the ground nut. The green detector produces a signal indicative of the extent to which the ground nut is mechanically damaged, and also produces a gating signal. A comparison signal is derived from these first and second signals and is passed by way of a gate and a level detector to an ejector. The gating signal controls the operation of the gate in dependence upon the extent to which the ground nut being viewed is mechanically damaged, so that the ejector is actuated by comparison signals of a predetermined level only when the extent to which the ground nut is mechanically damaged does not exceed a predetermined value.