Olive fruit detachment force against pulling and torsional stress

Abstract

Olive harvesting often requires high hand labour, considering that workers, with long poles or hand held devices, aid trunk shaker due to low harvesting efficiency. Currently, fruit detachment force (FDF) and fruit fresh weight were used to predict harvesting efficiency, although during harvesting process, fruit is subjected to bending and twisting movement besides pulling forces simulated by FDF measurements. For these reasons, the aim of the present study was to determine FDF evolution under different stalk twisting angles. In order to provide more information about mechanical behaviour of olive stalk, a trial was carried out during ripening process on four olive (Olea europaea L.) cultivars: Frantoio, Arbequina, Leccino and Maurino. FDF under traction force was measured after applying different stalk twisting angles (0°, 90°, 180°, 270°, 360°, 540°, 720º). FDF was considered to be 0 when fruit was detached from the bearing branch during the twisting process. Fruit weight, firmness, ripeness index and oil content were also measured to determine the optimal period for olive harvesting and olive ripening stage at each sampling date. FDF was significantly reduced, usually over 180º, when stalk was rotated before applying the pull force to measure FDF, keeping differences along fruit ripening process. Moreover, stalk twisting was an important variable for olive detachment, considering that fruits detached without pulling forces varied between 10.7 and 58.8% of the total fruits according with the different sampling dates. For these reasons, present and future harvesting systems, should take advantage of stalk susceptibility against torsion or bending strain to increase harvesting efficiency.Additional keywords: fruit retention force; olive harvesting; stalk twisting; stalk spinning; fruit rotation; trunk shaker; fruit physics. Abbreviations used: DOY (day of year according to National Snow and Data Center -NSIDC-, from 1 to 365 or 366 in a leap year); FDF (fruit detachment force, this value represents the pulling force at which fruit was detached from bearing branches); FW (fruit fresh weight).

Fruit removal forces of early stage pickling cucumbers for harvest automation

“…Torsional forces were not investigated in this study, but Castillo-Ruiz (2018) found that twisting and bending increased the harvesting efficiency for olives, thereby achieving accelerated detachment. Therefore, the question remains as to whether or not it is sufficient to apply torsional forces to the cucumber fruit to disconnect it rather than using a cutting device.…”

“…The range of FRF determined for cucumbers was generally larger than that of olives and apricots. Almeida et al, 2015 determined the FRF relationship to fruit mass to increase harvesting efficiency, but in general with increasing fruit size the FRF increases (Lavee et al, 1982;Castillo-Ruiz et al, 2018). In the 2018 field trial, the average ratio of FRF to mass was determined to be 73 for cucumbers, the values ranged from 13 to 364.…”

“…A recent Australian study concerning olive cultivars found that FRF decreased from the first harvest to the fifth harvest (Alowaiesh et al, 2016). Castillo-Ruiz et al (2018) found that FRF decreased when it was measured after applying stalk-twisting angles. For sour cherries, the FRF describes the ripening process.…”

Design and experiment of the comb-brush harvesting machine with variable spacing for oil-tea camellia fruit

“…The investigation shows that the oil-tea fruits are mostly distributed within the layer of 500 mm away from the surface of the canopy. The lateral and longitudinal detachment force of the oil-tea fruits were measured [22,23] by a force gauge (HP-50, Yueqing Aidebao Instrument Co., Ltd., Yueqing, Zhejiang, China) and a self-made measuring fixture, as shown in Figure 1. The specifications of the force gauge are listed in Table 1.…”

Parameter optimization of winnowing equipment for machine-harvested Lycium barbarum L.

“…Based on previous research and references review (González-Montellano et al, 2012;Horabik & Molenda, 2016;Castillo-Ruiz et al, 2018;Chen et al, 2019;Zhao et al, 2019a,b), because the properties of L. barbarum are similar to the olives, some simulation parameters of olive can be cited based on the actual situation. Based on González-Montellano et al´s (2012) work, because ripe fruit were distributed dispersedly with less collision compared with the olives, the restitution coefficient between ripe fruit and ripe fruit and the same coefficient between ripe fruit and the input conveyor were 0.1 and 0.1, respectively.…”