A New Wireless Device for Real-Time Mechanical Impact Evaluation in a Citrus Packing Line

Abstract. Postharvest handling of fresh fruit is a potential source of bruising and damage, with significant consequences for fruit quality and marketability. In the last 30 years, different types of impact-recording devices (also called electronic fruits or pseudo-fruits) have been developed with the aim of measuring the impacts experienced by fruits during postharvest operations. The aim of this study was to develop and test a novel wireless instrumented sphere to study the critical points in a citrus packing line by measuring the impacts experienced by fruits in real-time. The non-commercial device was based on a MEMS (micro-electro-mechanical system) sensor node with a sensing range from ±1×g to ±400×g (g = 9.8 m s -2 ), a ferroelectric RAM (FRAM) memory, a radio frequency (RF) transmitter, a microcontroller, and a 75 mAh lithium battery. The sensor node was placed inside a plastic ellipsoid case with a total weight of 100 g to represent a ‘Tardivo di Ciaculli’ mandarin. An FR receiver allowed real-time transmission of the measured data. Tests were performed in the Consorzio del Mandarino Tardivo di Ciaculli packing line (Palermo, Italy). Total acceleration values, representing the stresses experienced by fruit in the packing line, were studied using a variance component model. The results showed that total acceleration remained below 20×g in most of the measurements, but considerably higher values, up to 80×g, were obtained between the brushing and waxing machines. In particular, waxing was identified as the most critical operation based on the impact transmitted to the fruit. Our system proved to be effective for immediate on-line assessment of the accelerations experienced by fruits, allowing prompt intervention to guarantee fruit quality in postharvest operations. Highlights A novel, wirelessly instrumented sphere was developed and tested to study the critical points in a fruit packing line. The total acceleration experienced by the fruits was studied using a variance component model. The system was proven effective in online assessment of the accelerations experienced by fruits. Keywords: Acceleration, Damage, Instrumented sphere, Mandarin, Postharvest.