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Revalorization of wet olive pomace through polyphenol extraction and steam gasification

Final Report Summary - PHENOLIVE (Revalorization of wet olive pomace through polyphenol extraction and steam gasification)

Executive Summary:
PHENOLIVE puts together a multidisciplinary group of SMEs and RTDs, which expertise covers olive oil and olive pomace oil production processes and equipment, advanced technologies applied to process optimization, solutions based on plant extracts and biomass gasification.
The PHENOLIVE project was conceived as a solution for the revalorization of by-products from olive mills and olive pomace oil extraction industry, aiming at recovering high-added value polyphenolic compounds from 2-phase pomace (Wet Olive Pomace - WOP). Moreover, the final dry product of the pomace oil extraction industry (Exhausted Olive Pomace - EOP) is fed to a gasification plant, allowing the extraction plant to be self-sufficient in heat and power.

Project Context and Objectives:
Olive farming represents 8-9% of the total agricultural land in Spain, Italy and Portugal and 20% in Greece. Overall, the EU counts with 10,000 olive mills, most of which are SMEs, with an annual olive oil production reaching around 2M tons. The European olive oil extraction industry generates around 7.5tons/year of WOP, the main by-product of the modern two-phase continuous extraction process implemented in 100% olive mills in Spain and 50% worldwide (being progressively adopted in Italy, Greece or Turkey).
While the management of olive mill wastewater has been extensively investigated, the peculiar physico-chemical characteristics of this new waste fraction (WOP) generated by the 2-phase system, a paste with around 60% water, make its management complex, calling for the development of new adapted management solutions. Current uses of this by-product include biological treatments, direct combustion for heating or power generation or drying and subsequent pomace oil extraction.
The PHENOLIVE project has focused on pomace oil extraction plants, in which the WOP generated by the mechanical extraction process is further extracted using chemical methods (hexane solvent extraction) to obtain the so-called pomace oil. This is a widespread process, yet it has some disadvantages like the high operational costs due to the required drying step to reduce humidity content from 60% down to 8%.
WOP contains a high diversity of high-added value polyphenolic compounds that are not recovered in the oil fraction due to their polarity. The excellent biological properties of olive polyphenols as antioxidants and their free radical scavenging, antimicrobial and anticarcinogenic activity are widely recognized. Among them, the most widely known are Hydroxytyrosol, Tyrosol and Oleuropein. The extraction process and further purification steps depend on the properties of the raw material. Most applications developed to date for olive polyphenols are based on the isolation from the liquid fraction of 3-phase olive mill wastewater. However, the progressive upgrade of modern facilities to the more efficient 2-phase process, with lower water needs, requires a fully adapted extraction process to extract polyphenols from WOP. PHENOLIVE has applied an innovative technology for cell permeabilisation to enhance the release of the polyphenols, followed by a customized sequence of concentration /purification steps.
On the other hand, EOP has been used for the first time as a fuel for steam gasification in an innovative design consisting of a Dual Fluidized Bed reactor.

Project Results:
For the first period of the project, based on the specifications provided by PBIO, the RTD partners members of the consortium defined the lines of work. The RTD performers also counted on the technical support from technology manufacturers EFFITECH (experts in high power and pulsed power systems), HAKKI (manufacturer of equipment for the olive oil industry) and REPOTEC (engineering and construction of small to medium sized biomass gasification plants).
During the first period of the project, a strong collaborative partnership was forged in which companies and research centres with distant areas of expertise have worked together to develop a suitable solution for the olive oil industry. The multidisciplinary character of the consortium has boosted the organization of training activities, which in the first period have mostly taken the shape of training seminars. Starting on the second year of the project training activities will progressively focus on technology demonstration.
High effort was invested during the first period in the characterization of the different olive waste fractions and their potential for (i) polyphenol recovery and (ii) use as gasification fuel. An in-depth characterization of the different sample fractions provided by end user MORA was undertaken. Physico-chemical properties and polyphenol content analyses were performed for all fractions (wet, dry and exhausted olive pomace). The potential of exhausted pomace for use as fuel in steam gasification plant was also characterized, providing essential information for the development of the application. In addition, special attention was put in defining the protocols to follow throughout the project to evaluate the performance of the system.
During the second period, the designed parts composing the system were implemented. The result was a fully integrated system capable of processing 100kg of WOP per hour. A first validation of the PEF system took place at AMP in which laboratory trials took place for the PEF system in order to define the necessary components for polyphenol extraction/purification unit. The entire system was then validated at MORA’s families for during 3 weeks. A total of 13 samples were collected and sent to AMP for analysis. These 13 liquid extracts were analysed (total polyphenols, Tyrosol and Hydroxytyrosol concentrations). Then each sample was evaporated and freeze-dried. Once conditioned into a powder form total polyphenols, Tyrosol and Hydroxytyrosol concentrations were analysed in each sample.
These results obtained during the industrial validation of PHENOLIVE confirm the fact that the extraction/purification unit allows to obtain extracts rich in polyphenols. The results have also been compared with commercial olive based extracts. This comparison indicates that PHENOLIVE extract is not the most concentrated in Hydroxytyrosol. Nevertheless, its concentration remains comparable to other commercial preparation. This is highlighting the efficacy of the PHENOLIVE demonstrator. The extract can be used as an alternative method to supply Hydroxytyrosol for olive based products manufacturers.

Potential Impact:
The residue generated by the olive oil process (WOP) has a high water content (up to 65%) and may contain between 2-8 g. polyphenols/Kg pomace. More than 80% of the total polyphenol content in olives is lost in this waste material, which is commonly used for further extraction of pomace oil using organic solvents. The solid waste generated in the pomace oil extraction process has a low humidity (10-15%) and is usually sold as biomass.
During the work carried out in PHENOLIVE the consortium has achieved to revalorize this waste of the pomace oil producers by:
(i) Developing a pre-competitive prototype allowing the recovery of polyphenolic compounds as a high added value product using a unique combination of Pulsed Electric Field and successive purification steps.
(ii) Assessing the potential of steam gasification of the resulting solid waste to recover electricity and heat for the whole process, creating profit from the surplus.
PHENOLIVE identified a great potential in the use of WOP as a source of Hydroxytyrosol, Tyrosol and Oleuropein which are known for their antioxidant activity and thus have a high added value. Hydroxytyrosol is one of the few natural antioxidants whose health beneficial claims have been accepted by the European Food Safety Agency. There is indeed a wide potential market for natural extracts, including cosmetics, functional foods, supplements, preservatives in industrial production or animal health. The total worldwide market for polyphenols reached revenues of 390M€ in 2012, with an expected growth of 27% per year between 2011 and 2016. Polyphenol market revenues are still dominated by grape and green tea products, but olive polyphenols are progressively earning a place in the market and demand is increasing. This represents a unique market opportunity for PHENOLIVE.
The consortium has successfully implemented and validated the PHENOLIVE concept and it is expected to have a great impact on the competitiveness of the pomace oil extraction industry (e.g. MORA) thanks to sales of the polyphenol extract and savings in electricity thanks to self-sufficient production through steam gasification.
The SMEs in the consortium are already planning for future commercialization of the polyphenol recovery technology bringing benefits to all consortium SMEs: EFFITECH would be directly involved in the manufacturing and commercialization of the actual polyphenol extraction machinery; PBIO would provide further processing, refinement and quality control to the extract as well as the market network for commercialization of the purified polyphenols. Through PHENOLIVE, REPOTEC will also assess the potential of the use of EOP, a product available in great amounts in olive oil producing countries, for use as fuel in steam gasification, opening the possibilities to access a new market.
Furthermore, PHENOLIVE will help European SMEs in the olive oil sector implement innovative environmental management solutions while increasing their competitiveness.
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