Abstract: Optical sorting adds value to cereal crops by removing blemished grains and foreign material. Sortex have been designingand manufacturing optical sorting machines for bulk inspection and grading of food for over 50 years. In this presentation, weoutline the fundamental principles underlying the design and operation of an optical sorting machine in terms of the four mainfunctions of feed mechanism, inspection system, image processor and ejection system.The Z-Series is the very latest machine made by Sortex. The innovative design of the Z-Series has resulted in a step change inthe performance achievable by optical sorting. This technological innovation has created new applications for optical sortingwithin the cereal grain industry. Results are presented of the performance of the Z-Series for sorting cereal grains. The resultsinclude the removal of dark, discoloured, un-hulled and foreign material from Buckwheat at throughputs of up to 14,000 kg/hour.