Improvements in citrus packing lines to reduce the mechanical damage to fruit

Citrus fruits destined to the fresh market are subject to several treatments in packing lines with the aim of lengthen shelf-life, increase commercial value, and comply with the rules on marketing. During the treatments, fruits collide with each other and with components of the machines and undergo mechanical damage that can be very serious. Therefore, operators make changes to the machines in order to reduce number and intensity of impacts. This paper reports the results of a study on the impacts suffered by oranges during packing operations, carried out by using an instrumented sphere IS100. Experimental measurements were conducted in a packing house equipped with two packing lines, where they were both traditional and innovative machines (regarding the empting and the filling of the bins, the release of the fruits from the sizing machines, the transfer of the fruits between belt conveyors), specifically designed to reduce the mechanical impacts to the fruits. The results showed that the innovations were effective in reducing the intensity of the impacts, expressed in terms of acceleration. The maximum acceleration was always lower (from 47 to 83 %) with respect to the conventional machines, whereas the average number of impacts per replicate was lower in the sizing machines (−6 %) and during the emptying of the bins (−36 %), but was higher during the transfer of the oranges between belt conveyors (+33 %) and during the filling of the bins (+73 %). The increase in the average number of impacts depends from the fact that the innovative systems “accompany” the fruits towards the exit, causing a greater number of impacts of lower intensity.