Olive oil pomace utilization

Olive oil pomace utilization

Extraction and separation of hydroxytyrosol and other polyphenic compounds

The olive oil pomace is the by-product resulting from obtaining olive oil using the 2-phase technique, and its generation is currently an environmental problem due to its polluting nature. Reanga Química is working on a treatment process for the extraction of the polyphenolic compounds of interest, mainly hydroxytyrosol with important characteristics as a natural antioxidant and great potential in the food and cosmetic industry, mainly, and that allows the best use of the resulting fractions.

The imposition of the two-phase system for obtaining olive oil from the nineties of the last century, although it has reduced water consumption in the oil mills and has eliminated the problem of olive oil mill waste water contamination (a highly polluting aqueous residue produced in the previous three-phase process), it has introduced a new by-product, olive oil pomace.

This by-product can be considered rather a waste given its little current use and that, since it contains the components of the old former olive oil mill waste water (polyphenols with high phytotoxic power and high BOD and COD), it shares its contaminating characteristics. Being much more humid than the old pomace, its drying prior to the extraction of the pomace oil is uneconomical given the large amount of water to be removed, added to the fact that the high temperatures to which it must be heated cause transformations in the oil that reduce its quality, as well as the formation of toxic compounds such as benzopyrenes. This has lowered consumer confidence in pomace oil. In addition, the higher content of sugars in the alperujo with respect to the traditional pomace causes a greater deterioration in the drying equipment.

For this reason, the treatment of the alperujo that has begun to prevail is the separation of oil by means of a review or a second centrifugation and, subsequently, the obtaining of heat energy through the combustion of the rest of the alperujo, as the least bad of the ways of eliminating the residue.
However, this treatment does not allow taking advantage of the different components of the olive oil pomace. Of these components, polyphenols stand out, particularly hydroxytyrosol (HT). HT has a much higher antioxidant power than the substances currently used in the food industry and also contributes to foods to which it adds beneficial nutraceutical properties for health
Finally, the composition of the olive oil pomace, rich in cellulose and lignin, is similar to biomass of forest and agricultural origin, and therefore makes it a potential raw material for obtaining energy and chemicals in the current context of development of the green and circular economy. To be able to use the components of this biomass, it is necessary to carry out the separation of the same by means of a treatment with water in conditions of high pressure and temperature that produces the breakdown of the material in a process known as autohydrolysis.
The project consists of the investigation of a treatment of autohydrolysis to olive oil pomace that allows the separation of its valuable components (cellulose and lignin, mainly) and the extraction of hydroxytyrosol, as well as the subsequent selective separation using adsorption techniques on hydroxytyrosol resins and others. polyphenolic compounds of high value and interest.