The gari-making process involves several unit operations (U.O.), some of which strongly influence the quality of the end-product. Two contrasting process scales (laboratory-scale vs conventional) were compared in order to identify which U.O. were affected by the change of scale. U.O. that changed end-product characteristics depending on process scale were deemed critical; whereas U.O. that resulted in similar characteristics were deemed robust. The classification depended on quality attributes considered: rasping and roasting were critical for physical properties, in particular particle size which ranged from 0.44 to 0.89mm between the two process scales; and robust for biochemical properties. In contrast, fermentation and pressing were critical for biochemical properties such as lactic acid content (0.93 to 1.88g/100g dry matter after pressing), which influences the perception of flavour; and robust for physical properties. This classification between critical and robust operations help quality control of gari, by pinpointing which U.O. control specific quality characteristics.