Exploring the extraction of the bioactive content from the two-phase olive mill waste and further purification by ultrafiltration

Abstract

The two-phase olive mill waste is enormously produced in the Mediterranean area. This major waste is significantly rich in bioactive compounds that are highly valued by industry, such as phenolic and triterpenic compounds. Here, a thorough study of the most suitable solvent, extraction time and temperature for the large-volume, solid-liquid extraction of bioactive compounds has been made, in order to achieve maximum concentrations of the target compounds. Ultrasound effect has been considered. A deep characterization of the extracts by high-performance liquid chromatography coupled with electrospray-quadrupole-time of flight-mass spectrometry (LC-ESI-qToF-MS) has contributed to evaluate the effect of the operational parameters on the extraction performance. Forty-four compounds have been found and classified in their corresponding chemical families. At the optimum experimental conditions (EtOH 50% (v/v), 40 °C, ultrasound-assisted), more than 6.8 mg/g of bioactive content was recovered, and it was later purified by means of ultrafiltration. The membrane UP005 retained a significant percentage of the organic matter, whereas most of the bioactive compounds were recovered in the permeate. This contributed not only to revalorize this waste, but also to reduce its organic load and phytotoxicity, thus protecting the ecosystem of the final disposal zone of the residue.