Olive oil is a high-value, edible oil which is appreciated for its flavor as well as health properties due to its high oleic acid content and high levels of natural antioxidants such as polyphenols and tocopherol. Extraction of olive oil is quite an efficient process; however, there are still points of improvement. Pulsed electric field processing (PEF) is a non-thermal, low-energy technology that can reduce processing-time and increase extraction yield of olive oil processing plants.
Traditional olive oil extraction
Olive oil is located in the cells of the pulp of the olive fruit and is extracted exclusively from olives by means of mechanical procedures. The most common systems for mechanical extraction of olive oil comprise of a crusher, a malaxer and a decanter where the oil is separated through centrifugation. While crusher and decanter operates continuously, the malaxer that is located between these two continuous steps work in batches and this is the bottleneck of the processing plants.
Malaxation of the olive paste has a big influence on the extraction yield but also on the quality and composition of the final product. Therefore, maximizing the extraction yield without modifying the phenolic content and sensory properties of olive oil, requires optimization of the main operating conditions of malaxation.
PEF in Olive oil extraction
Disruption of the cell envelopes of the olive pulp that act as a physical barrier is required to facilitate the oil release during malaxation. Although the crushing step is a very effective process, in the current extraction process a percentage of the oil remains inside olive pulp cells. PEF is a physical non-thermal processing method that may complement the crushing step by the formation of pores in cell membranes that were not disrupted by the crusher.
Within the EU funded FieldFOOD project, a PEF treatment chamber was located after the crusher in a line with a processing capacity of 4 Tn/h. PEF treatment improved the extraction between 4.6 to 5.6 g of extracted olive oil per kilogram of processed olives for a malaxation time of two hours. When the malaxation time was reduced to 1 hour, the application of a PEF treatment increased an average of about 10 g of extracted olive oil per kilogram of processed olives. The polyphenol content of the oil was increased between 10-50% compared to the oil obtained after 2 hours of malaxation. The PEF treatment neither affects the parameters legally established by EU Regulation (EEC/2568/91) to measure the level of quality of the virgin olive oil nor bad flavor or taste were detected in the oil obtained from olive paste treated by PEF.
Total cost including both investment and energy consumption to establish a PEF treatment in an olive oil extraction plant are estimated between 0.038-0.02 €/L of oil for plants that process between 30 to 60 Tn/day respectively.
Within FieldFOOD project, PEF technology was tested and validated for five applications: olive oil, fruit juices, tomato peeling, cider and red wine. Benefits derived from the introduction of the PEF technology depended strongly on the specific application. Modular, portable, low cost PEF modulators developed during the project allow companies to evaluate this technology in the above-mentioned sectors or for new applications. For more information visit the FieldFOOD website or contact the project coordinator Javier Raso.
FieldFOOD an EU funded initiative
FieldFOOD stands for: Innovative food processing technologies.
For whom: Food processors of plant based food such as Wineries, Olive oil companies, Tomato products companies, Fruit juices companies and Cidery.
Objective: Provide innovative solutions to overcome existing bottlenecks that prevent theimplementation of Pulsed Electric Fields (PEF) in the food industry.
Reason: Effects deriving from PEF processing are very attractive to the food industry in order to improve food quality and process efficiency, reduce energy inputs and enhance eco-friendly processes.
How: By conducting a systematic process analysis of the processing lines of the different companies for a successful integration of the PEF technology in order to replace or complement the existing processing and by designing modular portable low-cost pulse generators to be install in the processing plant of the companies involved in the project.
Areas of interest: Food processing, Equipment manufacturing, Food safety, food quality, sustainability.
When: From April 2015 to April 2018.
Funded by: European Commission (635632-FieldFOOD- H2020).
Partners: Research institutions with well-established expertise in PEF technology: University of Zaragoza (Spain), Technical University of Berlin (Germany) ProdAl scarl (Italy), University College of Dublin (Irland). Manufacturer of PEF generator: Energy Pulse Systems (Portugal).
End-users of the technology: Bodegas Aragonesas (Spain), Agrinarsa (Spain), F.D.D-Industria conserve Alimentari (Italy), Diesdorfer (Germany) , The Apple farm (Ireland). Promoters of technological transfer: EFFOST (Netherlands). Expert on evaluation of food process sustainability: CIRCE (Spain).
Coordination: Javier Raso. University of Zaragoza (Spain).