Use of Portable Devices and an Innovative and Non-Destructive Index for In-Field Monitoring of Olive Fruit Ripeness

A new non-destructive index of absorbance difference (IAD), calculated with different wavelengths as references, near the chlorophyll absorbance peak or that for anthocyanin, has been used to determine the fruit ripening of several fruit species using portable devices such as Standard DA-Meter® and Kiwi-Meter®. In this study, for the first time, the application of the IAD was evaluated on single, intact olives of the Leccino cultivar, as a single non-destructive maturity index to follow ripening in the field, directly on the tree. The IAD determined by both devices was found to be useful for monitoring the olive ripening, however, better performance was achieved with the Kiwi-Meter®. In fact, the IAD determined by this device was more effective at measuring all the studied olive ripening parameters in the calibration and validation datasets with acceptable accuracy. Specifically, better performance of the IDA by Kiwi-Meter® was observed in estimation of the color index (R2 = 0.817, DRMSEC = 0.404 and RPIQ = 3.863 for calibration and R2 = 0.752, DRMSECV = 0.574 and RPIQ = 3.244 for validation), confirming its potential for evaluating the degree of olive ripeness. This novel index has significant applicative possibilities, since it would allow rapid, on-site screening of the best harvesting time to improve the olive production in terms of both yield and quality.

Effect of Brown Marmorated Stink Bug (Halyomorpha halys Stål.) Infestation on the Phenolic Response and Quality of Olive Fruits (Olea europaea L.)

Olives ripen in the late autumn and represent a good source of nutrients that Halyomorpha halys uses to prepare for diapause. This is the first study to investigate the impact of H. halys infestation on the phenolic response and olive fruit quality in the pierced tissue of damaged fruits and in the non-pierced part of damaged fruits of ‘Istrska belica’ and ‘Pendolino’ cultivars. Both total phenolic content and antioxidant capacity contents significantly increased in the infested fruits of the cultivar ‘Istrska belica’. Total phenolic content in the pierced tissue of damaged fruits increased by 10.7%, while the content of AC in the non-pierced tissue of damaged fruits increased by 7.11% and in the pierced tissue of damaged fruits by 6.1% compared to control. A total of 44 individual phenolic compounds were identified, 21 of them increased in at least one cultivar after infestation. Huge increases in phenolic content were observed in both cultivars, particularly for flavones, secoiridoids, anthocyanins, and flavonols in the pierced tissue of damaged fruits. The most responsive individual phenolic compound in both cultivars was oleuropein. Its content in the pierced tissue of damaged fruits increased by 44.7% in the cultivar ‘Pendolino’ and for 82.6% in the cultivar ‘Istrska belica’.