A clean and green technology for oleuropein rich extract from Olea europaea by-product

Considering the intense trend towards nutraceuticals and functional foods enriched with natural additives, and the great development in the cosmetic industry, it is obvious that it is necessary to study on the extraction of natural products. The current challenge is to develop the most effective alternative method by employing less energy, chemicals and unit operations. In the present study, automatic solvent extraction (AMSE) has been operated as a Green Extraction technology. Olive tree (Olea europaea) by-product (leaf) has been extracted by AMSE. Its yield has been evaluated according to its total phenolic (TPC), flavonoid (TFC) and oleumpein contents. Free radical scavenging activity of the product was also quantified by two different in vitro tests (2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)). 3-factor and 3-level Central Composite Design (CCD) was employed to design the experimental study as well as modelling the experimental data and optimizing the AMSE process. The concentration of ethanol (solvent solution) was statistically the most significant (p < 0.0001) parameter affecting the AMSE of bioactive ingredients from olive leaves. The optimal conditions (similar to 0.7 mm olive leaf particle with 80 % (v/v) ethanol solution for 30 min) have been determined to achieve the highest yields (216.39 mg gallic acid equivalent of TPC, 338.21 mg catechin equivalent of TFC and 67.25 mg of oleuropein per gram dried leaf), which are in convincing agreement with the actual values (<2 % error).

Automated summary

In this study, automatic solvent extraction (AMSE) was used to extract natural bioactive ingredients from olive tree leaves, resulting in high yields of phenolic and flavonoid compounds. The experiment was designed and optimized using a 3-factor, 3-level Central Composite Design (CCD), with ethanol concentration found to be the most significant factor affecting the extraction process. The optimal conditions were determined to achieve the highest yields, with results showing convincing agreement with actual values.