01 April 2020
At European level, the valorization of food processing by-products has been directed to the integrated “biorefinery concept” through a number of different policies and funding opportunities. Biorefineries generate a number of different biobased products such as biobased chemicals, biofuels, biobased composites, fibers and bioenergy. In Greece, the olive sector and its processing by-products industry comprise an area of great interest for valorization purposes for a number of reasons and opportunities by the biorefinery approach such as the production of many food additives and antioxidants. The cultivation and processing of the harvested olive fruits yields various by-products such as field residues or prunings (leaves, twigs, wood) and mill residues (pomace and waste water). These by-products are an interesting source of phenolics. The total polyphenols market was estimated in 2010 to about 2.2k t of polyphenols (Frost & Sullivan) is calculated that Greece has an annual discharge of polyphenols of about 2.4k t polyphenols. Which implies a huge resource for polyphenols extraction.
However, the options for integration of phenol extraction technology in the olive mill facilities needs further evaluation as the volume of the market for specific extracts is not yet known. Protocols for extraction of (poly)phenolic components (such as oleuropein, hydroxytyrosol, chlorogenic acid or verbascoside) have been described in literature.
In AGROinlOG we tested the effect of different solvents for the extraction of phenolics from olive mill waste residues. In addition, some of the phenolic components were identified such as oleuropein, hydroxytyrosol, 1,2 dimethoxy benzene, rutin and caffeic acid. It was shown that the total amount of phenolics is both dependent on the type of extraction and the solvent used. Furthermore, the different types of olive mill waste residues play an important role in the extraction of phenolics.
Recent biochemical, pharmacological and other studies have shown that (poly)phenols possess strong radical scavenging capacities and can play an important role in for example protecting against oxidative damages and cellular aging. The effect is also dependent on the type of (poly)phenols. For instance, hydroxytyrosol, primarily found in the olive leaves and pulp, has not only been shown to promote heart health, but may also protect against neurodegenerative diseases such as Alzheimer. Some of the phenolic extracts have been patented leading to commercial applications. we have designed different valorization route concepts of extracts developed within the AGROinLOG project. Extraction methodologies, the form of the final extraction and the content of the target compounds were taken into account.
Furthermore, an inventory was made for barriers and the effect of the National policy (Greece) for bringing olive mill processing by-products to the market. AGROinLOG has provided recommendations for solutions and the way forward for the valorization of the untapped source of (poly)phenolics from the side-products of the olive industry in Greece.