Mechanical Harvesting of Apricots

Abstract

An inertia type limb shaker hydraulically, powered and driven by the tractor power take-off, was designed and constructed for the mechanical harvesting of apricots. The study included some properties of apricot fruits, the apparent stiffness with respect to limb diameter, the time needed to shake a limb, optimum frequency and amplitude to obtain maximum fruit removal with minimum reactive force, limb amplitude, the effects of limb and tree properties on the fruit removal percentage, fruit damage, harvesting rate of the shaker; and comparisons with other harvesting methods. Harvesting rate was calculated by weighing both the harvested and unharvested apricot fruits. Fruit damage was evaluated from the modulus of elasticity of apricot fruit before and after harvesting. In order to study fruit damage, the effect of surface of different materials were examined: plastic canvas; nylon; and sponge. In the tests, the limbs were shaken at 20, 30, 40, 50 and 60 mm amplitude of the connecting rod attached to the crankshaft and 10, 15 and 20 Hz frequencies for optimum shaking time. The results were analysed according to the maximum fruit removal percentage. The limb amplitude was calculated using the apparent stiffness, masses of shaking mechanism, shaker arm and reduced mass of limb. Shaking time, frequency and amplitude for a limb were found as 5 s, 15 Hz, and 40 mm, respectively. Limb position, limb length and tree size affected the fruit removal percentage at the 5% significance level. The least fruit damage was obtained with the plastic canvas catching surface. The time required to harvest an apricot tree by hand and by traditional and mechanical harvesting methods were 400, 20, and 6 min, respectively. The inertia type limb shaker showed great promise and did not cause any damage to the limb and bark.

Introduction

Turkey is the biggest apricot producer and has approximately 20% of the total production of the world. The production of apricots in Turkey in 1998 was 538 000 t. The largest quantity is from the Hacıhaliloǧlu apricot variety. There are 12 million apricot trees in Turkey and all of them are generally harvested using the traditional method where the limbs are shaken with a stick, by hand or by shoving. The apricot fruits then fall directly onto the ground or are caught on a catching surface; the fruits are finally collected by hand and put into cases. This type harvesting is time consuming and labour intensive. In addition, it results in high levels fruit damage. The harvesting of apricot has not been mechanised until recently in Turkey and there has been a very short period of maturity stage available for harvesting. The labour is in short supply during this period. In order to eliminate these difficulties and disadvantages, mechanical harvesting of apricot is necessary and very important for Turkey. This study was conducted in Malatya which is a city in the east of Turkey and where apricot trees are widely grown.

There are two broad approaches to the mechanical harvesting considerations; one is the mass harvesting method, harvesting indiscriminately from the whole tree or a portion, without direct concern for individual fruits. The other is individual fruit harvesting, harvesting each fruit as distinct and separate from adjacent fruits. In individual fruit harvesting, several fruits could be harvested at the same time by separators (Schertz & Brown, 1968). Examples of detaching device being considered for the mass harvesting of fruit include limb shakers and trunk shakers. The basic principle of limb shaking is based on the transmission of vibratory forces to the limb.

A major problem associated with mechanical harvesting is fruit damage. In order to reduce fruit damage, the most common approach has been to remove the fruit by shaking the trees and to collect them on a catching surface placed beneath the tree. This method has shown considerable potential for fruits to be processed, such as prunes, peaches, apricots, sweet and sour cherries (Fridley et al., 1964).

The intentions of this paper is to give emphasis to the mechanical harvesting of apricot and to provide the necessary properties of apricots for developing an inertia type limb shaker.