Olive Mill and Winery Wastes as Viable Sources of Bioactive Compounds: A Study on Polyphenols Recovery

Abstract

In this study, the recovery of polyphenols from olive oil mill and winery waste was investigated. The performance of ultrasound assisted extraction (UAE), microwave assisted extraction (MAE), and pressurized liquid extraction (PLE) was assessed using ethanol–water mixtures, which are compatible with food, nutraceutical, and cosmetic applications. The extraction efficiency from olive pomace and lees samples was evaluated in terms of total polyphenol content (TPC), determined by high performance liquid chromatography (HPLC) and Folin–Ciocalteu assay. The effect of solvent composition, temperature, and time was analyzed by response surface methodology. Ethanol:water 50:50 (v/v) was found to be a suitable solvent mixture for both kinds of samples and all three extraction techniques. The performance of the extraction techniques was evaluated, under optimal experimental conditions, with a set of different representative samples of residues from olive oil and wine production. Overall, the best extraction efficiency for olive pomace residues was provided by MAE (ethanol:water 50:50 (v/v), 90 °C, 5 min), and for wine residues by PLE (ethanol:water 50:50 (v/v), 100 °C, 5 min, 1 cycle). However, the results provided by UAE (ethanol:water 50:50 (v/v), 30 min) were also suitable. Considering not only extraction performance, but also investment and operational costs, UAE is proposed for a future scaling up evaluation. Regarding olive pomace as a source for natural phenolic antioxidants, olive variety and climatic conditions should be taken into account, since both influence TPC in the extracts, while for winery residues, lees from red wines are more suitable than those from white wines.

Novel Processes for the Extraction of Phenolic Compounds from Olive Pomace and Their Protection by Encapsulation

“…The UAE treatment was confirmed to be particularly effective for the recovery of hydroxytyrosol, maslinic acid, and oleanolic acid from olive pomace compared to the conventional one [ 32 ]. Tapia-Quirós et al [ 33 ] effectively extracted phenolic compounds from olive pomace by applying UAE for 30 min with 50% ( v / v ) ethanol, proposing this technique as an ideal candidate for future increased evaluation. By combining ultrasounds with enzymes, the extraction efficiency of phenolic compounds from olive pomace can be further improved.…”

“…According to the results, the microwave treatment (600 W at 50 °C for 5 min) resulted in extracts with 8%, 24%, and 22% higher concentration of hydroxytyrosol, maslinic acid, and oleanolic acid, respectively, than those obtained by conventional extraction for 240 min. Tapia-Quirós et al [ 33 ] and Jurmanović et al [ 36 ] effectively extracted phenolic compounds from olive pomace by applying MAE at 90 °C for 5 min with 50% ( v / v ) ethanol, and for 10 min with 20% ( v / v ) ethanol, respectively.…”

Antioxidant Properties of Olive Mill Wastewater Polyphenolic Extracts on Human Endothelial and Vascular Smooth Muscle Cells

“…Other wastes are also produced during the filtration processes and during the storage time when the solid components migrate to the tank bottoms, generating sediments. These waste products are rich in bioactive compounds and can be therefore considered valuable byproducts to be exploited for further uses [ 39 , 40 ]. Although OMWs are effluents capable of degrading soil and water quality, with serious negative effects on the environment [ 7 ], studies have revealed that they contain high concentrations of antioxidants, such as phenolic molecules [ 41 ].…”

“…Although OMWs are effluents capable of degrading soil and water quality, with serious negative effects on the environment [ 7 ], studies have revealed that they contain high concentrations of antioxidants, such as phenolic molecules [ 41 ]. However, since the quality of OMW compounds differs according to the olive variety, the technological process of olive oil production, storage time, and climatic conditions [ 40 ], it is imperative to evaluate the technological processes employed in OMW processing in order to obtain valuable bioactive compounds. In this regard, phenolic compounds derived from OMW have been reported to show interesting biological properties [ 10 , 39 , 40 ].…”

“…However, since the quality of OMW compounds differs according to the olive variety, the technological process of olive oil production, storage time, and climatic conditions [ 40 ], it is imperative to evaluate the technological processes employed in OMW processing in order to obtain valuable bioactive compounds. In this regard, phenolic compounds derived from OMW have been reported to show interesting biological properties [ 10 , 39 , 40 ]. Nonetheless, yet a large amount of crusher residues remain without actual application, since only small quantities are used as natural fertilizers, biomass fuel, additives in animal feed, and activated carbon.…”