Non-contact fruit ripening monitoring using a radiofrequency passive resonator

A high sensitivity radiofrequency (RF) passive resonator is used to investigate the feasibility of fruit ripening assessment by non-contact sensing of fruit dielectric property changes. To do so, kiwifruit samples of similar size and ripeness are monitored during 14 days using the RF resonator, used as an inductive sensor. The recording of the sensor impedance enables monitoring of the fruit complex dielectric permittivity changes induced by the ripening process. These results are compared to mechanical tests carried out on the kiwifruit samples during ripening, which validate the ability of the proposed RF sensor to monitor the ripening process. These preliminary results open the way to developing a low-cost, non-contact and non-destructive assessment of the fruit ripening process.