Overcoming Olive Harvesting Challenges

 

BARD project aims to reduce table olive harvesting costs by developing a cost-effective harvesting system for small and large growers

 

Table olives are among the oldest fermented vegetables in the Mediterranean basin. They are important in multiple countries’ economies, including the U.S. and Israel. Despite the worldwide increase in demand for table olives as a healthy functional food, the industry is declining. This is due to the high production costs, primarily as a consequence of the manual labour needed for pruning and harvesting. Most growers replace olive with more profitable, mechanically pruned and harvested nut crops. Harvesting is the major cost of production for table olive. Some olive growers are using trunk shakers that are used to harvest nuts with limited success.

The willowy olive architecture prevents the effective transmission of vibrational energy in large trees from the trunk to the small peripheral branches where the fruits are located. High fruit detachment force and low fruit weight are even less suited to trunk shaking. For a trunk shaker to be effective, a large amount of energy is required. This damages the tree at the point of attachment, the trunk. Also, large, irregular trunks in older orchards are too large and misshapen to be effectively grasped by a shaker head. Among the other factors that need to be considered in the harvesting system is the fact that mechanical harvesting of the most popular (‘Manzanilla’) cultivar bruises the fruits.  And this translates to undesired browning facilitated by enzyme activity.

A BARD-funded research project led by Prof. Reza Ehsani, UC Merced, Prof. Arnon Dag, ARO,  Prof. Louise Ferguson, UC davis and Prof. Ayelet Fishman, Technion, aims to reduce table olive harvesting costs by developing a cost-effective harvesting system for small and large growers. The research teams include food scientists, engineers, and horticulturists who are working together to address the primary components of mechanically harvesting table olives. The research project objectives are to develop a mechanical harvester for table olives, and to determine the best postharvest treatments of mechanically harvested table olives. Once the harvesting techniques are set and post-harvesting treatment is determined, groundwork needs to be done to assist growers in adapting orchards for mechanical harvesting by training, pruning, and cultivar selection. The research team plans to develop a grower input and education program. This will facilitate the adoption of mechanical harvesting.

The new harvesting machine will combine trunk and canopy-contact shaking to optimize the shaking energy for fruit removal. This will minimize fruit damage. Current trunk shakers use hydraulic motors; the new system uses electric motors, sensors, and smart control algorithms to develop an intelligent machine that can accommodate the different shapes of trees to produce sufficient energy for efficient fruit removal. This system will enable the development of an intelligent harvesting machine. The combination of postharvest treatment of mechanically harvested olives with organic acids, chelators, and lye, and alternative cultivars to ‘Manzanilla,’ (such as ‘Hojiblanca’), will reduce the browning of fruit. Fermentation and subsequent sensory analysis will confirm the acceptability of the product by the consumer.