Phenolic profile and antioxidant activities of olive mill wastewater

Effects of Hydroxytyrosol Supplementation on Performance, Fat and Blood Parameters of Broiler Chickens

The study aimed to evaluate the effects of dietary supplementation of hydroxytyrosol (HT) on performance, fat, and blood parameters of broilers. In total, 960 male chicks were distributed into four treatments groups with 12 replicates with 20 birds per pen, with varying HT levels (0, 5, 10, and 50 mg/kg of feed) added to the basal diet from 1 to 42 days old. Feed intake, body weight gain, and feed conversion ratio were evaluated. Enzymes related to liver injury were evaluated in blood. Fatty acid profile and malondialdehyde (MDA) concentration were determined in the breast meat. Dietary supplementation of HT did not improve broilers' performance (p > 0.05). Birds fed 50 mg HT/kg had lower AST, ALT, and GGT concentrations (p ≤ 0.05), whereas broilers fed 5, 10, and 50 mg HT/kg, had lower TBIL concentrations (p ≤ 0.05). Breast meat of broilers fed 50 mg HT/kg had lower lipid content, saturated fatty acid, unsaturated fatty acids, MDA concentrations (p ≤ 0.05), and polyunsaturated fatty acids (p < 0.0001). In summary, supplementation of 5, 10, and 50 mg HT/kg does not improve the performance of broilers, but the dose of 50 mg HT/kg helps the liver against inflammation and improves fat parameters.

Replacement of Vitamin E by an Extract from an Olive Oil By-Product, Rich in Hydroxytyrosol, in Broiler Diets: Effects on Growth Performance and Breast Meat Quality

The hypothesis of this experiment was that a liquid rich in hydroxytyrosol (HT) obtained from "alperujo", an olive oil by-product, could replace part of the added vitamin E (VE) as an antioxidant in poultry diets. There were five diets that differed exclusively in the substitution of supplemental VE (0 to 40 mg/kg, with differences of 10 mg/kg) by HT (30 to 0 mg/kg, with differences of 7.5 mg/kg). The basal diet was based on corn and soybean meal and provided 10 mg VE/kg. From 0 to 39 d of age, the growth performance of the birds was not affected by diet. The birds were slaughtered at 39 d of age to evaluate the quality of the breast, and malonaldehyde concentration, pH, color, and drip loss were measured. In terms of meat lipid oxidation, the combination of 22.5 mg HT/kg and 10 mg of added VE/kg equalized to a diet supplemented with 40 mg VE/kg. Meat color improved in broilers fed 7.5 mg HT/kg and 30 mg VE/kg. It is concluded that once the nutritional requirements of the birds in VE are satisfied, the dietary supplementation with the olive oil by-product rich in HT can be used as a strategy to spare VE in broiler diets.

Modeling the antimicrobial effects of olive mill waste extract, rich in hydroxytyrosol, on the growth of lactic acid bacteria using response surface methodology

The objective of this study is to assess the inhibitory effects of an aqueous extract from olive oil mill waste (alperujo) on the growth of a lactic acid bacteria (LAB) cocktail consisting of various strains of Lactiplantibacillus pentosus and Lactiplantibacillus plantarum species. For this purpose, response surface methodology was employed using two independent variables (pH levels 3.5-5.55; hydroxytyrosol concentration ranging from 0.93-2990 ppm). The response variable was the average inhibition per treatment on the LAB cocktail (expressed as a percentage). The developed model identified significant terms, including the linear effect of hydroxytyrosol and pH, their interaction, and the quadratic effect of pH. Maximum inhibition of the LAB cocktail was observed at progressively higher concentrations of hydroxytyrosol and lower pH values. Therefore, complete inhibition of LAB in the synthetic culture medium could only be achieved for concentrations of 2984 ppm hydroxytyrosol at a pH of 3.95. These findings suggest that extracts derived from "alperujo" could be utilized as a natural preservative in acidified foods with a bitter flavor and antioxidant requirements.

Maceration and liquid-liquid extractions of phenolic compounds and antioxidants from Algerian olive oil mill wastewater

Olive oil mill wastewater (OMW) is a major waste stream generated in olive oil industry. It is highly polluted due to phenolic compounds. The present study focused on the physicochemical properties of OMW as well as the quantitative and qualitative effects of two extraction methods of phenolic compounds which were liquid-liquid and maceration methods. Spectrophotometry and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) were adopted to quantify the phytochemical contents and the phenolic compounds. The extract obtained by the maceration method showed the highest yields of total polyphenol, flavonoid, and tannin contents. The LC-MS results revealed the presence of 16 phenolic compounds in the macerated, and only 12 phenolic compounds were found in the extract of the second method. Quinic acid was identified as the most abundant compound. Moreover, the macerated extracts possessed the highest antioxidant potential as evidenced by their strong ferric reducing antioxidant power (FRAP) and their 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging activities. The phytochemical contents, as well as the antioxidant potentials of OMW after extraction using maceration, were significantly greater than using liquid-liquid method. Therefore, maceration seemed to be the most effective method for extracting phenolic compounds from OMW. The OMW constitute a rich source of natural phenolic compounds that could be used as a potential source of natural antioxidants.

Identification of Phenolic Compounds Extracted from OMW Using LC-MS

The extraction of olive oil produces annually huge quantities of Olive Mill Wastewater (OMW) that are considered as a source of pollution due to their high concentration in organic matter. This study aims to valorize Olive mill wastewater and investigates the effect of the extraction method and solvents on the contents and profiling of phenolic compounds and their antioxidant potential. It was revealed that the liquid-liquid method using ethyl acetate is the most effective followed by the maceration using chloroform/methanol (1:1), their polyphenol contents are respectively at 1.17 g GAE/L of OMW and 1.07 g GAE/L of OMW. In addition, the antioxidant activity was studied using ABTS test. It has shown that the methanolic extract has the best antioxidant activity at 15.75 mg/L. Moreover, we noticed a negative correlation between the phenolic compounds' concentration and their antioxidant activity which indicates that the phenolic profile may not be the same in the different extracts that's why a primary identification of the phenolic profile using UHPLC-MS was monitored and the results showed different chromatographic profiles between the samples.

Response Surface Modeling and Optimization of the Extraction of Phenolic Antioxidants from Olive Mill Pomace

Bioactive compounds from olive mill pomace (OMP) were extracted through a two-step solid-liquid extraction procedure considering four factors at five levels of a central composite rotatable response surface design. The influence of the process variables time of the primary extraction (2.0-4.0 h), solvent-to-sample ratio during the primary extraction (5.0-10.0 mL/g), time of the secondary extraction (1.0-2.0 h), and the solvent-to-sample ratio during the secondary extraction (3.0-5.0 mL/g) were examined. The content of bioactive compounds was determined spectrophotometrically, and the individual phenolic compounds were evaluated by reserved-phase high-performance liquid chromatography (RP-HPLC). The Derringer's function was used to optimize the extraction process, and the best conditions were found to be 3.2 h for the primary extraction, 10.0 mL/g for the solvent-to-sample ratio and 1.3 h for the secondary extraction associated with a solvent-to-sample ratio of 3.0 mL/g, obtaining a total phenolic content of 50.0 (expressed as mg gallic acid equivalents (GAE)/g dry weight (dw). The response surface methodology proved to be a great alternative for reducing the number of tests, allowing the optimization of the extraction of phenolic antioxidants from OMP with a reduced number of experiments, promoting reductions in cost and analysis time.

Biorecovery of olive mill wastewater sludge from evaporation ponds

Olive mill wastewater (OMW) resulting from the olive oil extraction process is usually disposed of in evaporation ponds where it concentrates generating a sludge that pollutes the ponds nearby area. In this study, four bio-treatments were applied for the in-situ bioremediation and valorization of OMW sludge: Landfarming, phytoremediation, composting and vermicomposting. In all cases, the OMW sludge was added with organic residues (mushroom compost, rabbit manure, and chicken manure). The bio-treatments were carried out in duplicate, inoculated and non-inoculated, to determine the effect of a specialized fungal consortium (Aspergillus ochraceus H2 and Scedosporium apiospermum H16) on the efficacy of the bio-treatments. The evaluation of chemical parameters, toxicity, and functional microbial biodiversity revealed that the four techniques depleted the toxicity and favored the stimulation of functional microbiota. Landfarming and phytoremediation allowed the decontamination and improvement of soils. Composting and vermicomposting also offered high-quality products of agronomic interest. Inoculation improved the bioremediation effectiveness. Biological treatments are effective for the safe recovery of contaminated OMW sludge into high-quality services and products.

Catalytic Steam Reforming of Biomass-Derived Oxygenates for H2 Production: A Review on Ni-Based Catalysts

The steam reforming of ethanol, methanol, and other oxygenates (e.g., bio-oil and olive mill wastewater) using Ni-based catalysts have been studied by the scientific community in the last few years. This process is already well studied over the last years, being the critical point, at this moment, the choice of a suitable catalyst. The utilization of these oxygenates for the production of “green” H2 is an interesting alternative to fuel fossils. For this application, Ni-based catalysts have been extensively studied since they are highly active and cheaper than noble metal-based materials. In this review, a comparison of several Ni-based catalysts reported in the literature for the different above-mentioned reactions is carried out. This study aims to understand if such catalysts demonstrate enough catalytic activity/stability for application in steam reforming of the oxygenated compounds and which preparation methods are most adequate to obtain these materials. In summary, it aims to provide insights into the performances reached and point out the best way to get better and improved catalysts for such applications (which depends on the feedstock used).

Specific adsorbents for the treatment of OMW phenolic compounds by activation of bio-residues from the olive oil industry

A series of adsorbents was developed by physical (CO₂) and chemical (KOH) activation of two bio-residues: olive stones (OS) and wood from olive tree pruning (OTP). The physicochemical properties of such materials were determined and correlated with their adsorptive performance in the removal of phenolic compounds of olive mill wastewater (OMW). Adsorption isotherms and kinetics of single phenolic acids, as well as the kinetics for competitive multi-compound adsorption, were fitted by applying different models, though Langmuir and pseudo-second order models fitted better the experimental results, respectively. The intraparticle diffusion model pointed out that mesoporosity reduces the influence of phenolic compounds' restrictions in the external film diffusion of the adsorbent particle-solution interphase, but adsorption capacity linearly increases with the micropore volume accessible to N₂ at -196 °C (and also with BET surface area), while diffusion into ultramicropores (<0.7 nm, determined by CO₂-adsorption) is slow and presents minor influence on the total adsorption capacity. After saturation, thermal regeneration of spent adsorbents allows the removal of adsorbed products, enabling the reuse of samples whilst maintaining a significant performance.

A Potential Valorization Strategy of Wine Industry by-Products and Their Application in Cosmetics-Case Study: Grape Pomace and Grapeseed

Grape pomace and grapeseed are agro-industrial by-products, whose inadequate treatment generates socioeconomic and environmental concerns. Nevertheless, it is possible to valorize them by extracting their bioactive compounds, such as antioxidants (phenolic compounds), vitamin E and fatty acids. The bioactive compounds were extracted using solid-liquid extraction. The yields for phenolic compounds were 18.4 ± 0.4% for grape pomace, and 17.4 ± 0.4%, for grapeseed. For the oil, the yields were 13.3 ± 0.2% and 14.5 ± 0.3% for grape pomace and grapeseed. Antioxidant capacity was assessed by the assay with 2,2-diphenyl-1-picrylhydrazyl (DPPH), and showed that phenolic extract has higher antioxidant capacity than the oils. Grape pomace and grapeseed extracts exhibit, correspondingly, values of 90.8 ± 0.8 and 87.5 ± 0.5 of DPPH inhibition and IC₅₀ of 48.9 ± 0.5 and 55.9 ± 0.7 μg_extract·mL_DPPH⁻¹. The antimicrobial capacity was assessed by the disk diffusion test, and revealed that, phenolic extracts inhibit the growth of Staphylococcus aureus and Staphylococcus epidermidis. The obtained extracts were incorporated in 10 face cream formulations, with slight modifications in quantities of formulation stabilizers. Their stability was studied for 35 days, and this revealed the possibility of incorporating extracts and oils obtained from by-products as antioxidants in cosmetics, and replacing synthetic ones. As a future recommendation, microencapsulation of the extracts should be performed, in order to increase their stability.

State of knowledge on chemical, biological and nutritional properties of olive mill wastewater

The Mediterranean olive oil industries are producing annually a massive quantity of olive mill wastewater (OMWW). Unfortunately, the OMWW is released arbitrarily in the nature without any pretreatment. Thus, it exhibits a high toxicity against the whole natural ecosystem including, microorganisms, plants and animals. In order to eliminate or reduce its pollution, OMWW must be properly treated prior to its release in the nature. In this regard, different treatment methods have been developed by researchers, but some of them were costly and others were inappropriate. Thus, more efforts should be made to save the nature from this pollutant. In the light of that, the current work summaries the state of knowledge regarding the OMWW from a chemical, biological, nutraceutical point of view, and the treatment methods that were used to eliminate its risk of pollution.

Olive Mill Wastewater Valorization through Steam Reforming Using Multifunctional Reactors: Challenges of the Process Intensification

Olive oil mill wastewater (OMW) is a polluting stream derived from the production of olive oil and is a source of environmental pollution; this is relevant in many countries around the world, but particularly in all the Mediterranean region where major producers are located. In this effluent, several pollutants are present—namely, sugars, fatty acids, and polyphenols, among others. Nowadays, to reduce the pollutant load, several treatment techniques are applied, but these technologies have numerous cost and efficiency problems. For this reason, the steam reforming of the OMW (OMWSR) presents as a good alternative, because this process decreases the pollutant load of the OMW and simultaneously valorizes the waste with the production of green H2, which is consistent with the perspective of the circular economy. Currently, the OMWSR is an innovative treatment alternative in the scientific field and with high potential. In the last few years, some groups have studied the OMWSR and used innovative reactor configurations, aiming to improve the process’ effectiveness. In this review, the OMW treatment/valorization processes, the last developments on catalysis for OMWSR (or steam reforming of similar species present in the effluent), as well as the last advances on OMWSR performed in multi-functional reactors are addressed.

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.

Olive mill wastewater phytoremediation employing economically important woody plants

In this study two plant species, Punica granatum L. and Myrtus communis L., have been tested as candidates for phytoremediation of olive mill wastewater (OMW) through recirculation in soil pilot units, according to the proposed patented technology by Santori and Cicalini [EP1216963 A. 26 Jun 2002]. Wastewater was treated in batches of low to high organics strength (COD: 2 700-45 700 mg/L) during summer months of two consecutive years. Dynamics of the most important wastewater parameters were investigated, and corresponding removal rates were estimated. During treatment of low organic load OMW, average removal rate of organics, phenolics, total nitrogen and total phosphorus were 0.68 g-COD/kg-soil d, 0.073 g-TPh/kg-soil d, 0.033 g-TN/kg-soil d and 0.0074 g-TP/kg-soil d respectively and plants proved to be tolerant to the OMW. During treatment of high organic load OMW removal rates were roughly 10-fold higher although phytotoxic symptoms were observed. Plants were found to contribute greatly to the OMW treatment process since organics removal rates in pilot units were found to be at least 10-fold higher than in wastewater treatment in non-vegetated soil. Plant species with high added value products such as pomegranate and myrtle trees were used in this study, improving the circular economy potential of the aforementioned technology. Moreover, its efficiency has been demonstrated by quantification of the overall removal rates of key constituents as well as the contribution of the plants in the OMW treatment.

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.

Applications of bioactive compounds extracted from olive industry wastes: A review

The wastes generated during the olive oil extraction process, even if presenting a negative impact for the environment, contain several bioactive compounds that have considerable health benefits. After suitable extraction and purification, these compounds can be used as food antioxidants or as active ingredients in nutraceutical and cosmetic products due to their interesting technological and pharmaceutical properties. The aim of this review, after presenting general applications of the different types of wastes generated from this industry, is to focus on the olive pomace produced by the two-phase system and to explore the challenging applications of the main individual compounds present in this waste. Hydroxytyrosol, tyrosol, oleuropein, oleuropein aglycone, and verbascoside are the most abundant bioactive compounds present in olive pomace. Besides their antioxidant activity, these compounds also demonstrated other biological properties such as antimicrobial, anticancer, or anti-inflammatory, thus being used in formulations to produce pharmaceutical and cosmetic products or in the fortification of food. Nevertheless, it is mandatory to involve both industries and researchers to create strategies to valorize these byproducts while maintaining environmental sustainability.

A Polyphenol-Rich Extract of Olive Mill Wastewater Enhances Cancer Chemotherapy Effects, While Mitigating Cardiac Toxicity

Cardiovascular toxicity remains one of the most adverse side effects in cancer patients receiving chemotherapy. Extra-virgin olive oil (EVOO) is rich in cancer preventive polyphenols endowed with anti-inflammatory, anti-oxidant activities which could exert protective effects on heart cells. One very interesting derivative of EVOO preparation is represented by purified extracts from olive mill waste waters (OMWW) rich in polyphenols. Here, we have investigated the anti-cancer activity of a OMWW preparation, named A009, when combined with chemotherapeutics, as well as its potential cardioprotective activities. Mice bearing prostate cancer (PCa) xenografts were treated with cisplatin, alone or in combination with A009. In an in vivo model, we found synergisms of A009 and cisplatin in reduction of prostate cancer tumor weight. Hearts of mice were analyzed, and the mitochondria were studied by transmission electron microscopy. The hearts of mice co-treated with A009 extracts along with cisplatin had reduced mitochondria damage compared to the those treated with chemotherapy alone, indicating a cardioprotective role. To confirm the in vivo results, tumor cell lines and rat cardiomyocytes were treated with cisplatin in vitro, with and without A009. Another frequently used chemotherapeutic agent 5-fluorouracil (5-FU), was also tested in this assay, observing a similar effect. In vitro, the combination of A009 with cisplatin or 5-FU was effective in decreasing prostate and colon cancer cell growth, while it did not further reduce growth of rat cardiomyocytes also treated with cisplatin or 5-FU. A009 cardioprotective effects towards side effects caused by 5-FU chemotherapy were further investigated, using cardiomyocytes freshly isolated from mice pups. A009 mitigated toxicity of 5-FU on primary cultures of mouse cardiomyocytes. Our study demonstrates that the polyphenol rich purified A009 extracts enhance the effect of chemotherapy in vitro and in vivo, but mitigates chemotherpy adverse effects on heart and on isolated cardiomyocytes. Olive mill waste water extracts could therefore represent a potential candidate for cardiovascular prevention in patients undergoing cancer chemotherapy.

Olive Mill Wastewater as Renewable Raw Materials to Generate High Added-Value Ingredients for Agro-Food Industries

Olive oil production represents an agro-industrial activity of vital economic importance for many Mediterranean countries. However, it is associated with the generation of a huge amount of by-products, both in solid and liquid forms, mainly constituted by olive mill wastewater, olive pomace, wood, leaves, and stones. Although for many years olive by-products have only been considered as a relevant environmental issue, in the last decades, numerous studies have deeply described their antioxidant, anti-inflammatory, immunomodulatory, analgesic, antimicrobial, antihypertensive, anticancer, anti-hyperglycemic activities. Therefore, the increasing interest in natural bioactive compounds represents a new challenge for olive mills. Studies have focused on optimizing methods to extract phenols from olive oil by-products for pharmaceutical or cosmetic applications and attempts have been made to describe microorganisms and metabolic activity involved in the treatment of such complex and variable by-products. However, few studies have investigated olive oil by-products in order to produce added-value ingredients and/or preservatives for food industries. This review provides an overview of the prospective of liquid olive oil by-products as a source of high nutritional value compounds to produce new functional additives or ingredients and to explore potential and future research opportunities.

Gluten-Free Breadsticks Fortified with Phenolic-Rich Extracts from Olive Leaves and Olive Mill Wastewater

Nowadays, food processing by-products, which have long raised serious environmental concerns, are recognized to be a cheap source of valuable compounds. In the present study, incorporation of phenolic-rich extracts (500 and 1000 mg kg⁻¹) from olive leaves (OL) and olive mill wastewater (OMW) into conventional gluten-free formulations has been exploited as a potential strategy for developing nutritious and healthy breadsticks with extended shelf-life. To this end, moisture, water activity (a_w), visual and textural properties, the composition of biologically active compounds (soluble, insoluble, and bio-accessible polyphenols), antioxidant activity, oxidation stability, and consumer preference of the resulting breadsticks were investigated. Fortified breadsticks had higher moisture and a_w, lower hardness, and similar color in comparison to the control, especially in the case of OL extract supplementation. All enriched formulations significantly affected the phenolic composition, as evidenced by the decrease in insoluble/soluble polyphenols ratio (from 7 in the control up to 3.1 and 4.5 in OL and OMW, respectively), and a concomitant increase in polyphenol bio-accessibility (OL: 14.5–23% and OMW: 10.4–15% rise) and antioxidant activity (OL: 20–36% and OMW: 11–16% rise). Moreover, a significant shelf-life extension was observed in all fortified breadsticks (especially in case of OMW supplementation). Sensory evaluation evidenced that 61% of the assessors showed a marked, but not significant, tendency to consider the sample supplemented with high levels of OL as a more palatable choice.

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)).

Plant Secondary Metabolites: An Opportunity for Circular Economy

Moving toward a more sustainable development, a pivotal role is played by circular economy and a smarter waste management. Industrial wastes from plants offer a wide spectrum of possibilities for their valorization, still being enriched in high added-value molecules, such as secondary metabolites (SMs). The current review provides an overview of the most common SM classes (chemical structures, classification, biological activities) present in different plant waste/by-products and their potential use in various fields. A bibliographic survey was carried out, taking into account 99 research articles (from 2006 to 2020), summarizing all the information about waste type, its plant source, industrial sector of provenience, contained SMs, reported bioactivities, and proposals for its valorization. This survey highlighted that a great deal of the current publications are focused on the exploitation of plant wastes in human healthcare and food (including cosmetic, pharmaceutical, nutraceutical and food additives). However, as summarized in this review, plant SMs also possess an enormous potential for further uses. Accordingly, an increasing number of investigations on neglected plant matrices and their use in areas such as veterinary science or agriculture are expected, considering also the need to implement "greener" practices in the latter sector.

Innovations in Smart Packaging Concepts for Food: An Extensive Review

Innovation in food packaging is mainly represented by the development of active and intelligent packing technologies, which offer to deliver safer and high-quality food products. Active packaging refers to the incorporation of active component into the package with the aim of maintaining or extending the product quality and shelf-life. The intelligent systems are able to monitor the condition of packaged food in order to provide information about the quality of the product during transportation and storage. These packaging technologies can also work synergistically to yield a multipurpose food packaging system. This review is a critical and up-dated analysis of the results reported in the literature about this fascinating and growing field of research. Several aspects are considered and organized going from the definitions and the regulations, to the specific functions and the technological aspects regarding the manufacturing technologies, in order to have a complete overlook on the overall topic.

Phenolic Compounds Obtained from Olea europaea By-Products and their Use to Improve the Quality and Shelf Life of Meat and Meat Products-A Review

Consumers are interested in consuming clean label foods. Replacing synthetic additives with natural alternatives (especially sources rich in polyphenols) is a valid solution to produce and also preserve foods, especially meat and meat products. Olea europaea leaves and olive pomace and wastewater contain polyphenols that can be explored in this context. In this review, we summarize the main aspects related to the phenolic composition, extraction conditions, antimicrobial potential, and antioxidant activity (in vitro and in vivo) of Olea europaea leaves, olive pomace and wastewater as well as their applications in the production of meat and meat products. This review found evidence that extracts and isolated polyphenols from the Olea europaea tree and olive processing by-products can be explored as natural antioxidant and antimicrobial additives to improve the preservation of meat and meat products. The polyphenols found in these residues (especially oleuropein, hydroxytyrosol and tyrosol) increased the redox state in the main meat-producing animals and, consequently, the oxidative stability of fresh meat obtained from these animals. Moreover, the extracts and isolated polyphenols also improved the shelf life of fresh meat and meat products (as additive and as active component in film) by delaying the growth of microorganisms and the progression of oxidative reactions during storage. The accumulated evidence supports further investigation as a natural additive to improve the preservation of reformulated muscle products and in the production of edible and sustainable films and coatings for fresh meat and meat products.

Ionizing Radiation Technologies to Increase the Extraction of Bioactive Compounds from Agro-Industrial Residues: A Review

Due to the growing demand in society for healthier foods, scientific communities are searching and developing new ingredients. In this context, agro-industrial residues, which can have a negative impact on the environment, represent a natural source for bioactive compounds and their recovery can contribute to economic and environmental sustainability. Ionizing radiation is a clean and eco-friendly technology that can be used to improve the extraction of bioactive compounds. The aim of this review, after presenting general aspects about bioactive compounds in agro-industrial residues and radiation technologies, is to focus on the effects of ionizing radiation on the extraction of bioactive compounds from these residues and related bioactive properties. Irradiated residues were demonstrated to have enhanced bioactive characteristics that turn the prepared extracts suitable for applications in food industry, resulting in high-added-value products as well as reducing adverse impacts on the environment.

A review on management of cardiovascular diseases by olive polyphenols

Noncommunicable diseases have increasingly grown the cause of morbidities and mortalities worldwide. Among them, cardiovascular diseases (CVDs) continue to be the major contributor to deaths. CVDs are common in the urban community population due to the substandard living conditions, which have a significant impact on the healthcare system, and over 23 million human beings are anticipated to suffer from the CVDs before 2030. At the moment, CVD physicians are immediately advancing both primary and secondary prevention modalities in high-risk populations. The cornerstone of CVD prevention is a healthy lifestyle that is more cost-effective than the treatments after disease onset. In fact, in the present scenario, comprehensive research conducted on food plant components is potentially efficacious in reducing some highly prevalent CVD risk factors, such as hypercholesterolemia, hypertension, and atherosclerosis. Polyphenols of olive oil (OO), virgin olive oil (VOO), and extra virgin olive oil contribute an essential role for the management of CVDs. Olive oil induces cardioprotective effects due to the presence of a plethora of polyphenolic compounds, for example, oleuropein (OL), tyrosol, and hydroxytyrosol. The present study examines the bioavailability and absorption of major olive bioactive compounds, for instance, oleacein, oleocanthal, OL, and tyrosol. This review also elucidates the snobbish connection of olive polyphenols (OP) and the potential mechanism involved in combating various CVD results taken up from the in vitro and in vivo studies, such as animal and human model studies.

Antioxidant and Antimicrobial Activity of Polyphenols Extracted after Adsorption onto Natural Clay “Ghassoul”

Natural polyphenols contained in olive mill wastewaters (OMW) have been usually associated with great bioactive properties as “antioxidants”. In this work, we recovered the polyphenols after adsorption onto natural clay “ghassoul” by different solvents: water, ethyl acetate, and methanol (PPW, PPA, and PPM, respectively) to avoid environmental pollution. Also, we tested the antioxidant activity of the extracted polyphenols by two methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH) and total antioxidant capacity (TAC). Then, we analyzed antimicrobial activity by the microdilution technique to determine at the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The OMW of the Fez-Meknes region has a very acidic pH, considerable amounts of mineral matter, and a high concentration of polyphenols and organic content. The results of the test from DPPH showed good antiradical potential for polyphenols extracted with water, but the TAC showed an important capacity for all extracts unless PPA. The antibacterial activity is not the same on the four bacteria studied (Escherichia coli, Salmonella sp, Staphylococcus aureus, and Enterococcus faecalis), and all extracts inhibit most tested germs that do not have the same MIC and the same sensitivity. Only the PPW showed the minimum bactericidal concentration (MBC) that is equal to 0.290 mg/mL for Salmonella sp and Staphylococcus aureus, which confirms that the extraction by water of the adsorbed polyphenols is an original solution to recover the polyphenols and also to obtain a natural phenolic antioxidant which can be used in the pharmaceutical, nourishment, and cosmetic industry.

New Liquid Source of Antioxidant Phenolic Compounds in the Olive Oil Industry: Alperujo Water

The current management of alperujo as the main solid by-product from the two-phase olive oil extraction system has led to the appearance of a new liquid effluent that until now was treated together with the alperujo itself. The composition and antioxidant properties of its bioactive components at different depths of the pond were studied using colorimetric and HPLC with UV and MS detectors, DPPH, reducing power and rancimat. The concentration of suspended solids varied between 1.71 and 8.49 g/L, total fat was between 0.74 and 1.47 g/L, and total phenols were found between 3.74 and 4.11 g/L, which included hydroxytyrosol, 3,4-dihydroxyphenylglycol and tyrosol as the main phenols. Two types of extracts were obtained through two industrial systems with ethyl acetate and by chromotography, with an average content in total sugars of 2.1% and 3.16%, total phenols of 17.9% and 28.6% and hydroxytyrosol of 51.5 and 79.0 mg/g of extract, respectively. The activity presented by the chromatographic extract was higher in terms of free radical sequestering capacity, reducing power and the inhibition of lipid oxidation. Obtaining bioactive extracts would improve the formulation of food with natural components and at the same time would be the first step in a biorefinery to improve the management of the new effluent.

Industrial-Scale Study of the Chemical Composition of Olive Oil Process-Derived Matrices

The effect of the industrial process and collecting period on produced olive oil and by-products was evaluated. Obtained results showed significant variations for the majority of quality indices before and after vertical centrifugation between all samples from the three collecting periods. All samples were rich in monounsaturated fatty acid: Oleic acid (C18:1) with a maximum of 69.95%. The total polyphenols and individual phenolic compounds varied significantly through the extraction process, with a significant variation between olive oil and by-products. Notably, the percentage of secoiridoids and their derivatives was significant in paste and olive oil, highlighting the activity of many enzymes released during the different extraction steps. Regarding antioxidant capacity, the most remarkable result was detected in olive oil and olive mill wastewater samples.

Sustainable Environmental Management and Valorization Options for Olive Mill Byproducts in the Middle East and North Africa (MENA) Region

Cultivation of olive trees and olive oil production have been considered as a legacy for the Mediterranean region. This custom represents a very important benefit for many nations in terms of wealth and health. However, huge amounts of by-products and waste are generated during olive oil production. This represents a serious environmental impact on land and water bodies if not properly handled. Olive oil extraction generates two waste streams, a solid waste called pomace and olive mill wastewater (OMWW), which has been considered as highly pollutant and phytotoxic waste. These wastes have high disposal costs and predominantly generated from small-scale enterprises that have limited financial resources to treat them properly before discharge to the environment. Besides being a serious environmental problem, OMWW has potential economic value that remains to be utilized such as: fertilizers, valuable antioxidants agents and fatty acids needed in human diet. Also, Olive pomace is a valuable renewable energy source with an energy density of 23 MJ/kg and has become an inexpensive alternative for fossil fuels. Aiming at adding value to the olive production sectors and potential valorization options for byproducts in the MENA region, international practices applied in olive mills wastes management’s and treatment methods used in major oil producing countries are presented.

Deriving valorization of phenolic compounds from olive oil by-products for food applications through microencapsulation approaches: a comprehensive review

Nowadays, olive oil consumption is correlated to many health benefits, essentially due to the presence of antioxidants, especially phenolic compounds, which fostered its intensive production worldwide. During olive oil extraction, through continuous or discontinuous processes, many olive oil by-products are generated. These by-products constitute an environmental problem regarding its management and disposal. They are phytotoxic and biotoxic due to their high content of phenolic compounds, presenting contrastingly relevant health benefits due to their potent radical scavenging activities. In the framework of the disposal and management of olive oil by-products, treatment, and valorization approaches are found. As currently, the majority of the valorization techniques applied have a null market value, alternative strategies for the obtainment of innovative products as fortified foods are being investigated. The recovery and valorization strategies of olive oil by-products may comprise extraction and further encapsulation of bioactive compounds, as an innovative valorization blueprint of phenolic compounds present in these by-products. The majority of phenolic compounds present in olive oil by-products possess limited application on the food industry since they are promptly amended by environmental factors like temperature, pH, and light. Consequently, they must be protected previously ending in the final formulation. Prior to foods fortification with phenolic-rich extracts obtained from olive oil by-products, they should be protected through microencapsulation approaches, allowing a sustained release of phenolic compounds in the fortified foods, without losing their physicochemical properties. The combined strategies of extraction and microencapsulation will contribute to promoting the sustainability of the olive oil sector and aid the food industry to obtain reinvented added-value products.

An Extract of Olive Mill Wastewater Downregulates Growth, Adhesion and Invasion Pathways in Lung Cancer Cells: Involvement of CXCR4

Several diet-derived compounds have been reported to exert antioxidant, anti-proliferative and anti-angiogenic effects in numerous cancers and could be beneficial in cancer prevention. Olive oil production involves the generation of an aqueous phase defined as olive mill wastewater (OMWW), a polluting effluent rich in soluble polyphenols. Here, we assessed the cancer preventive properties exerted by a purified extract of OMWW (A009) for its activity on lung cancer cell lines. Hydroxytyrosol, the most abundant polyphenol present in our A009 extracts, was used as reference molecule in the assays performed. Extracts from OMWW from two different olive oil cultivars were used. We found that the A009 extracts limit lung cancer cell proliferation in a dose and time dependent manner. These effects were associated with the induction of apoptosis. A009 extracts were effective in inhibiting adhesion capabilities on a fibronectin layer accompanied with a reduction in their ability to generate invasive sprouts in a Matrigel layer. The production of chemokine CXCL12 and CXCR4 receptor were reduced by treatment with the extracts. Also, A009 interfered with the production of proangiogenic and pro-inflammatory VEGF, CXCL8, and CCL2 (as detected by FACS analysis) in the lung cell lines. A009 extracts were able to decrease STAT3 phosphorylation in lung cancer cells. Our results show that A009 extracts reduced activities related to tumor cell behavior in lung cancer cell lines, suggesting that they could have a potential cancer preventive role.

Biodegradation of olive mill wastewater phenolic compounds in a thermophilic anaerobic upflow packed bed reactor and assessment of their toxicity in digester effluents

The extent of phenolic compounds' biodegradation was assessed utilizing un-treated olive mill wastewater (OMWW) fed to a high-rate thermophilic (55 ^οC) anaerobic upflow packed bed reactor (UPBR) and digester effluents (DEs) collected in different hydraulic retention times (HRTs) under steady-state operating conditions. In parallel, the toxicity of each sample was evaluated by performing the microbiotest Thamnotoxkit F™. The outcomes indicate complete biodegradation of 6 phenolic compounds-vanillic acid (VA), caffeic acid (CA), syringic acid (SA), o-coumaric acid (o-CA), oleuropein (OLEU), 4-ethylphenol (4-EP)-and notable removals of hydroxytyrosol (HT) and tyrosol (TYR), reaching up to 94.87 ± 0.04% and 93.92 ± 0.33%, respectively. 4-hydroxybenzoic acid (PHBA), p-coumaric acid (p-CA) and 3,4-dihydroxybenzoic acid (DBA) were recognized as the most recalcitrant and persistent compounds in the anaerobic effluents, being capable of modulating the toxic potential of DEs.

Treatment of olive mill effluent by adsorption on titanium oxide nanoparticles

Olive mills wastewater (OMW) causes a serious environmental problem in the olive oil producing countries. This is due to its high organic matter content (COD), acidic pH values, suspended solids and high content of phytotoxic and antibacterial phenolic compounds. In this study, titanium dioxide (TiO₂) as an adsorbent to reduce the COD value of the olive mill wastewater was investigated. Several variables were studied including the removal efficiency, effect of the initial COD value, amount of TiO₂, temperature and pH value. The results revealed that the adsorption reached equilibrium within <120 min. Isotherm studies showed that the adsorption equilibrium data is in agreement with Freundlich isotherm. In addition, the results showed that the adsorption process was spontaneous and exothermic. The kinetic study indicated that adsorption did follow a pseudo-second order reaction. Variation of the amount of the TiO₂ showed that using of 1.5 and 2 g/L of TiO₂ caused the COD to drop from 1000 ppm to about 100 ppm (equilibrium concentration) in about 120 min. However, the use of 1 g/L of TiO₂ exhibited almost the same effect on the COD-uptake, and the equilibrium concentration was about 400 ppm. The COD uptake was found to be inversely proportional with the temperature, pH value and the addition of salts such as sodium chloride (NaCl) and potassium chloride (KCl).

Olive Leaf Addition Increases Olive Oil Nutraceutical Properties

The aim of the present research was to study the effects of olive leaf addition (0 and 3%) on the major antioxidants and the antioxidant activity of Neb Jmel and Oueslati olive oils. Olives and leaves of the two Tunisian varieties were harvested during the 2016/2017 crop season. Both leaves and oils were characterised for their concentrations in phenolics, tocopherols and antioxidant power. Other parameters such as free acidity, peroxide value, chlorophyll and carotenoid concentrations were also taken into consideration. Compared to Oueslati, the Neb Jmel oil showed a lower free acidity (50%) and peroxide value (5.6-fold), and higher chlorophyll (1.6-fold), total phenolics (1.3-fold), flavonoid (3-fold) and oleuropein derivative (1.5-fold) concentrations, in addition to an increased antioxidant activity (1.6-fold). Leaf addition promoted a significant increment in total chlorophyll, α-tocopherol and phenolics in both varieties, above all in Oueslati oil, due to a higher abundance of bioactive constituents in the corresponding leaves. In particular, chlorophyll and carotenoid concentrations reached values twice higher than in Neb Jmel leaves, and flavonoids and oleouperin derivatives were three-fold higher. This prevented the oxidation and the formation of peroxides, reducing the peroxide value of the fortified oil to the half. The results provide evidence on the performance of the Tunisian Neb Jmel and Oueslati varieties, showing that their oils present a chemical profile corresponding to the extra virgin olive oil category and that, after leaf addition, their nutritional value was improved.

Application of Advanced Oxidation Processes for the Treatment of Recalcitrant Agro-Industrial Wastewater: A Review

Agro-industrial wastewaters are characterized by the presence of multiple organic and inorganic contaminants of environmental concern. The high pollutant load, the large volumes produced, and the seasonal variability makes the treatment of these wastewaters an environmental challenge. A wide range of wastewater treatment processes are available, however the continuous search for cost-effective treatment methods is necessary to comply with the legal limits of release in sewer systems and/or in natural waters. This review presents a state-of-the-art of the application of advanced oxidation processes (AOPs) to some worldwide generated agro-industrial wastewaters, such as olive mill, winery and pulp mill wastewaters. Studies carried out just with AOPs or combined with physico-chemical or biological treatments were included in this review. The main remarks and factors affecting the treatment efficiency such as chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total organic carbon (TOC), and total polyphenols removal are discussed. From all the studies, the combination of processes led to better treatment efficiencies, regardless the wastewater type or its physico-chemical characteristics.

Downregulation of Pro-Inflammatory and Pro-Angiogenic Pathways in Prostate Cancer Cells by a Polyphenol-Rich Extract from Olive Mill Wastewater

Dietary phytochemicals are particularly attractive for chemoprevention and are able to modulate several signal transduction pathways linked with cancer. Olive oil, a major component of the Mediterranean diet, is an abundant source of phenolic compounds. Olive oil production is associated with the generation of a waste material, termed 'olive mill wastewater' (OMWW) that have been reported to contain water-soluble polyphenols. Prostate cancer (PCa) is considered as an ideal cancer type for chemopreventive approaches, due to its wide incidence but relatively long latency period and progression time. Here, we investigated activities associated with potential preventive properties of a polyphenol-rich olive mill wastewater extract, OMWW (A009), on three in vitro models of PCa. A009 was able to inhibit PCa cell proliferation, adhesion, migration, and invasion. Molecularly, we found that A009 targeted NF-κB and reduced pro-angiogenic growth factor, VEGF, CXCL8, and CXCL12 production. IL-6/STAT3 axis was also regulated by the extract. A009 shows promising properties, and purified hydroxytyrosol (HyT), the major polyphenol component of A009, was also active but not always as effective as A009. Finally, our results support the idea of repositioning a food waste-derived material for nutraceutical employment, with environmental and industrial cost management benefits.

Synthetic olive mill wastewater treatment by Fenton's process in batch and continuous reactors operation

Degradation of total phenol (TPh) and organic matter, (expressed as total organic carbon TOC), of a simulated olive mill wastewater was evaluated by the Fenton oxidation process under batch and continuous mode conditions. A mixture of six phenolic acids usually found in these agro-industrial wastewaters was used for this purpose. The study focused on the optimization of key operational parameters of the Fenton process in a batch reactor, namely Fe²⁺ dosage, hydrogen peroxide concentration, pH, and reaction temperature. On the assessment of the process efficiency, > 99% of TPh and > 56% of TOC removal were attained when [Fe²⁺] = 100 ppm, [H₂O₂] = 2.0 g/L, T = 30 °C, and initial pH = 5.0, after 300 min of reaction. Under those operational conditions, experiments on a continuous stirred-tank reactor (CSTR) were performed for different space-time values (τ). TOC and TPh removals of 47.5 and 96.9%, respectively, were reached at steady-state (for τ = 120 min). High removal of COD (> 75%) and BOD₅ (> 70%) was achieved for both batch and CSTR optimum conditions; analysis of the BOD₅/COD ratio also revealed an increase in the effluent's biodegradability. Despite the high removal of lumped parameters, the treated effluent did not met the Portuguese legal limits for direct discharge of wastewaters into water bodies, which indicates that coupled chemical-biological process may be the best solution for real olive mill wastewater treatment.

Olive mill wastewaters: quantitation of the phenolic content and profiling of elenolic acid derivatives using HPLC-DAD and HPLC/MS2 with an embedded polar group stationary phase

Olive mill wastewaters (OMWs) are important by-products of olive oil production. The wide availability and the forbidding economic costs of OMWs disposal have generated interest in their possible exploitation as a sustainable source of polyphenols. The development and optimisation of improved analytical methods for the detailed characterisation of polyphenol molecular profiles after production and during storage conditions are thus required. A new analytical method based on reverse-phase HPLC separation of polyphenols in OMWs on an embedded-polar group (EPG) stationary phase is proposed as an alternative to conventional C18 columns. The procedure was used for the quantitation of 11 polyphenols, using diode-array detection (DAD), and achieving quantitation limits equal to or lower than 0.1 µg g^-1. The same chromatographic set-up, coupled with high resolution tandem mass spectrometry (HPLC/ESI-Q-ToF), allowed us to identify hydroxytyrosyl esters of elenolic acid, whose relative abundance is proposed for monitoring the ageing of OMWs during storage.

Novel Feed Including Olive Oil Mill Wastewater Bioactive Compounds Enhanced the Redox Status of Lambs

BACKGROUND/AIM

The aim of the present study was to investigate the antioxidant effects of a feed supplemented with polyphenolic additives from olive mill wastewater (OMW) on lambs.

MATERIALS AND METHODS

Lambs received breast milk until the postnatal period, and then they were divided into two groups and received control and OMW feed for 55 days. Redox biomarkers were measured in blood and tissues at days 15, 42 and 70 after feeding.

RESULTS

Feed supplemented with OMW reduced thiobarbituric acid reactive species and protein carbonyls and increased total antioxidant capacity, glutathione and catalase activity in both blood and tissues.

CONCLUSION

The administration of OMW-containing feed reinforced the antioxidant defense of lambs, which may improve their wellbeing and productivity. Additionally, this exploitation of OMW may solve problems of environmental pollution in areas with olive oil industries.