Megasonics

Commercial demonstration of megasonic technology for additional virgin olive oil recovery

The olive oil industry is striving to improve processing efficiencies of oil extraction at reduced cost, and preferentially using only physical means. The megasonics technology process being trialled in this project consists of treating the conditioned olive paste with high frequency ultrasound standing waves before oil separation with the decanter.

Megasonic pre-treatment has shown additional oil recovery of up to 2% in industrial trials at 350 kg/h and additionally demonstrated an increase in phenolic compounds in the olive oil, which relate to a healthier product and potentially extended shelf-life. Industry partners have advised that it is essential that the megasonic olive oil extraction technology is demonstrated at a higher process capacity to de- risk industry adoption and justify further investment for commercialisation. Consequently, this project comprises the design and commissioning of a megasonic vessel for olive oil processing plants running at 2000-3000 kg/h.

Trials will be held at an advanced Australian olive plant to evaluate and demonstrate extra virgin olive oil recovery, oil quality, and shelf life in an operational environment. The reduction of enzyme use and malaxation times will also be evaluated in this industrial setting.

To ensure that the outcomes are commercially relevant, this project brings together research, technology provider and industry partners, comprising Boundary Bend Ltd, CSIRO, Sonosys Ultraschallsysteme GmbH. and the University of Foggia.

In recent years, the application of high frequency ultrasound standing waves (megasonics) on olive paste has proven to provide additional olive oil extractabilities beyond 3% both at laboratory scale and in small industrial plants both in Australia and Italy at the 350 kg/h production scale. The technology demonstration involved a megasonic conditioning of the olive paste after malaxation (or paste conditioning through mixing and kneading) to further promote coalescence effects and further oil release before the decanter separation step. Findings demonstrated not only improvements in oil yield and extractability, but also an increase in the level of phenolic compounds in the olive oil, while maintaining sensory and chemical properties characteristic of extra virgin olive oil according to the Olive Oil Council standard.
The aim of this project was to demonstrate benefits of megasonics technology at 2.7 tonnes/h by providing increased oil recovery. A 1400 L size megasonic reactor system was designed for scale up trials to achieve residence times near 30 min. Trials with barnea and picual varieties were carried in a single processing line with and without megasonic application, showing improvements in extra virgin olive oil recovery of up to 3.9%. Other trials involved the megasonic treatments of pastes previously malaxed with enzyme and malaxation reduction trials from 90 to 60 min, also showed increased oil extraction in an industrial setting.

For further information please contact:

Dr Pablo Juliano, CSIRO: pablo.juliano@csiro.au