The level of mixing in the in-feed system was characterised using about 100 marker fruit (actual number used varied between runs). Fig. 3 shows the order of arrival of markers relative to the fruit stream for a run undertaken early in the research. At this point, no interventions had been taken to reduce the level of mixing through the in-feed system. The grader processed about 400 fruit min−1 and the spread of these markers represents about 20 min in time, or over three processed bins. The marker arrival data are described by an exponential distribution function (distribution mean, β=2519).