Biophenol extracts from olive oil mill wastewaters by membrane separation and adsorption resin

Integration of membrane processes for the recovery and separation of polyphenols from winery and olive mill wastes using green solvent-based processing

Winery and olive mill industries generate large amounts of wastes causing important environmental problems. The main aim of this work is the evaluation of different membrane separation processes like microfiltration, ultrafiltration, nanofiltration, and reverse osmosis for the recovery of polyphenols from winery and olive mill wastes in aqueous solutions. Membrane processes were tested separately in a closed-loop system, and by an integration in a concentration mode sequential design (open-loop). Feed flow rate was varied from 1 to 10 mL min^-1, and permeate samples were taken in order to measure the polyphenols concentration. The separation and concentration efficiency were evaluated in terms of total polyphenol content, and by polyphenols families (hydroxybenzoic acids (HB), hydroxycinnamic acids (HC), and flavonoids (F)), using high performance liquid chromatography. Results showed that MF and UF membranes removed suspended solids and colloids from the extracts. NF was useful for polyphenols separation (HB rejections were lower than for HC and F: HB rejections of 50 and 63% for lees filters and olive pomace extracts, respectively), and RO membranes were able to concentrate polyphenols streams (86 and 95% rejection from lees filters and olive pomace, respectively). Membranes sequential designs for lees filters and olive pomace extracts, using a selective membrane train composed by UF, NF and RO membranes, were able to obtain polyphenol rich streams and high-quality water streams for reuse purposes.

Recovery of Polyphenols from Agri-Food By-Products: The Olive Oil and Winery Industries Cases

The production of olive oil and wine are two of the main agri-food economic activities in Southern Europe. They generate large amounts of solid and liquid wastes (e.g., olive pomace, olive mill wastewater, grape pomace, grape stems, wine lees, and wine processing wastewater) that represent a major environmental problem. Consequently, the management of these residues has become a big challenge for these industries, since they are harmful to the environment but rich in bioactive compounds, such as polyphenols. In recent years, the recovery of phenolic compounds has been proposed as a smart strategy for the valorization of these by-products, from a circular economy perspective. This review aims to provide a comprehensive description of the state of the art of techniques available for the analysis, extraction, and purification of polyphenols from the olive mill and winery residues. Thus, the integration and implementation of these techniques could provide a sustainable solution to the olive oil and winery sectors.

The Valorisation of Olive Mill Wastewater from Slovenian Istria by Fe3O4 Particles to Recover Polyphenolic Compounds for the Chemical Specialties Sector

Olive oil production using three-phase decanter systems creates olive oil and two by-products: olive mill wastewater (OMWW) and pomace. These by-products contain the highest share of polyphenolic compounds that are known to be associated with beneficial effects on human health. Therefore, they are an attractive source of phenolic compounds for further industrial use in the cosmetic, pharmaceutical and food industries. The use of these phenolics is limited due to difficulties in recovery, high reactivity, complexity of the OMWW matrix and different physiochemical properties of phenolic compounds. This research, focused on OMWW, was performed in two phases. First, different polyphenol extraction methods were compared to obtain the method that yields the highest polyphenol concentration. Twenty-five phenolic compounds and their isomers were determined. Acidifying OMWW, followed by five minutes of ultrasonication, resulted in the highest measured polyphenol content of 27 mg/L. Second, the collection of polyphenolic compounds from OMWW via adsorption on unmodified iron (II, III) oxide particles was investigated. Although low yields were obtained for removed polyphenolic compounds in one removal cycle, the process has a high capability to be repeated.

Concentration of Bioactive Phenolic Compounds in Olive Mill Wastewater by Direct Contact Membrane Distillation

Olive mill wastewater (OMW), generated as a by-product of olive oil production, is considered one of the most polluting effluents produced by the agro-food industry, due to its high concentration of organic matter and nutrients. However, OMW is rich in several polyphenols, representing compounds with remarkable biological properties. This study aimed to analyze the chemical profile as well as the antioxidant and anti-obesity properties of concentrated fractions obtained from microfiltered OMW treated by direct contact membrane distillation (DCMD). Ultra-high performance liquid chromatography (UHPLC) analyses were applied to quantify some phenols selected as phytochemical markers. Moreover, α-Amylase, α-glucosidase, and lipase inhibitory activity were investigated together with the antioxidant activity by means of assays, namely β-carotene bleaching, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid (ABTS) diammonium salts, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and Ferric Reducing Activity Power (FRAP) tests. MD retentate—which has content of about five times greater of hydroxytyrosol and verbascoside and about 7 times greater of oleuropein than the feed—was more active as an antioxidant in all applied assays. Of interest is the result obtained in the DPPH test (an inhibitory concentration 50% (IC₅₀) of 9.8 μg/mL in comparison to the feed (IC₅₀ of 97.2 μg/mL)) and in the ABTS assay (an IC₅₀ of 0.4 μg/mL in comparison to the feed (IC₅₀ of 1.2 μg/mL)).

Extraction of betacyanins from Hylocereus polyrhizus (dragon fruit) peel and further enrichment by adsorption

Mixtures of water and ethanol were tested for the extraction of betacyanins from Hylocereus polyrhizus peel to obtain natural colorants. In order to obtain betacyanins in a purified form, adsorption was carried out with two types of multi-walled carbon nanotubes (MWCNTs; pristine MWCNTs and carboxylated MWCNTs) and two macroporous resins (X-5 and AB-8). Carboxylated MWCNTs showed the highest adsorption capacity. On the basis of static adsorption test, carboxylated MWCNTs were selected for kinetic and isotherm studies. Langmuir and pseudo-first-order models could describe the process well. According to the Langmuir model, the maximum monolayer adsorption amount of carboxylated MWCNTs was 84.6 mg/g. After purification on a chromatographic column packed with carboxylated MWCNTs, the content of H. polyrhizus peel betacyanins in the pigment product was 4.62%.

An Innovative Olive Pâté with Nutraceutical Properties

Food plays a central role in health, especially through consumption of plant-derived foods. Functional foods, supplements, and nutraceuticals are increasingly entering the market to respond to consumer demand for healthy products. They are foods, supplements, and ingredients which offer health benefits beyond the standard nutritional value. Some benefits are associated with phenolic compounds and phytochemicals with antioxidant properties. An olive pâté (OP) was added with antioxidants derived from olive mill wastewater (OMWW) to obtain a functional product rich in phenolic compounds. The olive pâté is produced from the ground olive pericarp, which shows an excellent natural antioxidant content. The OMWW is a waste product from oil processing, which is also rich in phenolic compounds. The result was a product rich in trans-resveratrol, OH tyrosol, and tyrosol in concentrations such as satisfying the European community’s claims regarding the possible antioxidant action on plasma lipids with excellent shelf-life stability. The total phenolic content was assayed by a colorimetric method, the antioxidant activity by the ABTS [(2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)] test, the phenolic profile by Q Exactive Orbitrap LC-MS/MS. The shelf-life stability was confirmed by yeast, molds, and total microbial count, pH, and water activity determinations, and the best pasteurization parameters were determined. The palatability was judged as excellent.