Olive Mill By-products Research Articles

Evaluation of immunomodulatory properties of phenolic extracts from olive mill by-products using Caco-2 cells and molecular docking analysis

The bioactive potential of phenolic extracts derived from olive mill solid by-product (OMSbP), also called alperujo, and olive mill water (OMW), remains a topic of significant interest due to the amount of these, especially in Mediterranean regions, and their potential health benefits. In this study, the antioxidant and immunomodulatory properties of phenolic extracts obtained from OMSbP and OMW (OMSbP-P and OMW-P, respectively) in intestinal cells were evaluated. Initially, phenol-rich extracts were prepared by ethanol/ethyl acetate extraction and were characterized by HPLC-DAD analyses. The in vitro antioxidant activity showed potent bioactivities for all extracts evaluated. Toxicity assays did not reveal adverse effects on Caco-2 cell viability at concentrations relevant to immunomodulatory activity. Subsequently, the immunomodulatory effects of these extracts were assessed by measuring gene expression of pro- and anti-inflammatory cytokines. The results demonstrate that both OMSbP-P and OMW-P exhibit significant immunomodulatory activities, as evidenced by modulated cytokine gene expression in intestinal cells. Furthermore, molecular docking analyses of the identified phenols with the TLR4/MD2 receptor showed binding affinity, increasing the evidence that these extracts could exert immunomodulatory activity. Overall, our findings suggest that OMSbP-P and OMW-P possess promising immunomodulatory properties in intestinal cells, thus emphasizing their potential as natural therapeutic agents for managing immune-related disorders and promoting gut health. Further elucidation of the molecular mechanisms underlying these effects and in vivo studies are warranted to fully exploit the therapeutic potential of these extracts.

A Comprehensive Study on Adsorption Kinetics and Equilibrium: Utilizing Olive Mill By-Products as a Sustainable Biosorbent for Cobalt (II) Removal

A Comprehensive Study on Adsorption Kinetics and Equilibrium: Utilizing Olive Mill By-Products as a Sustainable Biosorbent for Cobalt (II) Removal

Biochars Derived from Olive Mill Byproducts: Typology, Characterization, and Eco-Efficient Application in Agriculture—A Systematic Review

Biochars Derived from Olive Mill Byproducts: Typology, Characterization, and Eco-Efficient Application in Agriculture—A Systematic Review

Can Co-Composted Olive Mill by-Products be an Environmentally Conscious Approach for Enhancing Soil Fertility and Plant growth? A Review

Can Co-Composted Olive Mill by-Products be an Environmentally Conscious Approach for Enhancing Soil Fertility and Plant growth? A Review

Olive pomace bioactives for functional foods and cosmetics

The reuse and valorization of olive mill by-products, among others, is getting attention in the food and drugs-cosmetics sectors, due the recovery of their essential bioactive compounds in order to incorporate them as ingredients in functional foods, cosmetics, and pharmaceuticals. Olive pomace represents olive mill's main residue (by-product), and it is a sustainable and of low-cost renewable source of several bioactive compounds, while its valorization can reduce its environmental impact and make it an additional economic resource for food industries in a circular economy design. In this article, the natural bio-functional compounds of olive pomace with antioxidant and anti-inflammatory bioactivities are thoroughly reviewed. The incorporation of such bioactives as ingredients in functional foods and cosmetics is also discussed in detail. The limitations of such applications are also presented. Thus, promising techniques, such as encapsulation, and their applications for stabilizing and masking undesirable characteristics of such compounds, are also exhibited. The so far promising in vitro outcomes seem to support further in vivo assessment in trials-based setting.

Valorization of Olive Mill Byproducts: Recovery of Biophenol Compounds and Application in Animal Feed.

This study aimed to recover the phenols from olive oil mill wastewater, a major pollutant of the oil industry, by using spray-drying technology to produce a new feed with a nutraceutical value for animal feed supplementation and to evaluate its effect on the productivity and nutritional quality of ewe milk. Forty-five Sarda ewes in late lactation (150 ± 2 d) and with homogeneous live weight (52 ± 1.5 kg) were randomly allotted into three groups and fed with three dietary treatments containing increasing levels of polyphenols: 0% (C), 0.1% (T0.1), and 0.2% (T0.2) of dry matter. No effect of the dietary treatments was found on the milk yield and composition. Interestingly, milk urea content (p < 0.0001) and somatic cell counts (p < 0.001) decreased as the level of polyphenols inclusion in the diet increased. The inclusion of phenols (0.2% of dry matter) in the diet of sheep was effective in increasing the vaccenic (C18:1 trans-11) and rumenic acid (C18: cis-9 trans-11) levels, which are beneficial for human health. Finally, the recovery of polyphenols via spray-drying technology and their incorporation into a new fortified feed can be a valid strategy for naturally improving the nutritional value of milk while valorizing an oil industry byproduct, reducing environmental impact, and promoting waste reuse that is in line with circular economy principles.

Should extra virgin olive oil production change the approach? A systematic review of challenges and opportunities to increase sustainability, productivity, and product quality

Extra virgin olive oil is constantly gaining interest for its outstanding health and nutritional properties. However, the production process generates roughly four times more waste than the quantity of oil. For this reason, improvements in extra virgin olive oil production and in the valorisation of olive mill by-products are urgently needed, thus motivating this work. The first aim of this review is to summarise current knowledge regarding machines, plants, and processes in extra virgin olive oil production. The second aim is to suggest specific innovations and improvement strategies to increase sustainability, productivity, profitability, and quality. This review clearly highlighted the copious advantages of modern production plants, which can control oxidation processes, avoid temperature increases, and significantly improve the quality of extra virgin olive oil. However, the production chain must face the monumental environmental sustainability challenge. In this direction, this review highlighted that scientific and technological research has made great strides in managing olive mill by-products, suggesting several strategies related to the recovery of polyphenols and applications in agriculture, feed, and food. However, to succeed in this ambitious project, harmonious teamwork between European policies, states, regions, and private companies is needed.

Recovery and valorization of food industry by-products through the application of Olea europaea L. leaves in kombucha tea manufacturing

The present study investigated the application of a sustainable production model to the manufacturing technology of kombucha. In order to comply with the principles of circular economy, a newly-formulated beverage, obtained through the use of olive mill by-products as a fermentation substrate, was examined. The total polyphenol content, antioxidant activity and sensory profile of the final product was analyzed with the intention of evaluating the bioactive and sensory contribution made by olive leaves, when used in substitution of tea for kombucha fermentation. The initial level of oleuropein (394.7 mg/L) obtained in the olive leaves extract did not inhibit the natural fermentation process of Symbiotic Culture of Bacteria and Yeast (SCOBY). The addition of increasing percentages of the by-product during the fermentation produced several kombucha samples rich in secoiridoid bioactive compounds with a concentration of oleuropein and hydroxytyrosol ranged from 306.4 mg/L to 91.2 mg/L and from 29.0 mg/L to 9.3 mg/L, respectively. Since tea stands out as one of the main cost items in kombucha tea manufacturing, this study demonstrated that the use of olive leaves, as a polyphenol-rich substrate, may represent a viable strategy to valorize the agro-industrial waste, reduce production costs, preserve the antioxidant properties of kombucha and enrich its sensory profile.

High-rate in-vessel continuous composting of olive mill byproducts

The increasing production of agro-industrial organic residues in modern society is extremely concerning. One of the most polluting procedures in the agricultural industry is the production of olive oil. This process creates a large amount of waste with high organic load and phytotoxic components. In this study, composting of two-phase olive pomace (OP), olive leaves (OL) and dewatered anaerobic sludge (DAS) from an olive mill wastewater anaerobic digestion process was conducted in a pilot-scale in-vessel high-rate continuous composter. Five different feed scenarios were studied with different OP/OL ratio in the feed material, while the effect of the addition of pine tree bark pieces (PB) and DAS was examined. The OP:OL 95:5 % w/w ratio exhibited the best results in terms of product quality, while OL proved capable of acting as a bulking agent for the better aeration of the material. The final product in the optimum feed ratio was free of Salmonella spp., was stable in terms of static respiratory index (lower than 0.5 g O2 kg−1 VS h−1) but contained elevated E. coli levels (3.5 × 104 CFU g-1 with a limit of 1 × 103 CFU g-1), which was the only EU proposed compost quality criteria not met. The addition of a more easily degradable material in the feed mixture is expected to lead to elevated composting temperature and amend the presence of pathogens.

Effect of Processing on Phenolic Composition of Olive Oil Products and Olive Mill By-Products and Possibilities for Enhancement of Sustainable Processes

The bio-functional properties of olive oil products and by-products rely greatly on the proportions and types of the endogenous phenolics that may favorably/unfavorably change during various processing conditions. The olive oil industrial activities typically produce (i) olive oils, the main/marketable products, and (ii) olive mill by-products. The mechanical processing of olive oil extraction is making progress in some areas. However, the challenges inherent in the existing system, taking into consideration, the susceptibilities of phenolics and their biosynthetic variations during processing, hamper efforts to ascertain an ideal approach. The proposed innovative means, such as inclusion of emerging technologies in extraction system, show potential for sustainable development of olive oil processing. Another crucial factor, together with the technological advancements of olive oil extraction, is the valorization of olive mill by-products that are presently underused while having great potential for extended/high-value applications. A sustainable re-utilization of these valuable by-products helps contribute to (i) food and nutrition security and (ii) economic and environmental sustainability. This review discusses typical processing factors responsible for the fate of endogenous phenolics in olive oil products/by-products and provides an overview of the possibilities for the sustainable processing to (i) produce phenolic-rich olive oil and (ii) optimally valorize the by-products.

Monitoring Cocomposting of Agro-Wastes from Olive Mill By-Products and Poultry Manures

The potential of treating agro-wastes by recovering organic amendments for agricultural soils is promising for Mediterranean countries that produce olive oils. In this study, olive mill by-products...

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.

Exploiting Olive Mill Byproducts and Other Waste for Organic Weed Management

Weed management represents one of the most serious and costly challenges in organic crop production systems. Agricultural waste/byproducts might present phytotoxicity that can be exploited to control weeds. Two experiments were designed to study the effects of four concentrations of olive vegetation water (OVW) and a control water treatment (with no OVW) on cheeseweed (Malva parviflora L.) seed germination in petri dishes and pots. In a third experiment, two rates of four composts (crop residue mix (CR), olive pomace (OP), dairy/horse manure (DM), and an OP/DM mix) were mixed into a clay‒loam soil at 0.10 or 0.20 L L−1, to assess their effects on weed number and biomass, in addition to bell pepper (Capsicum annuum L.) growth. In the petri dish experiment, the three highest OVW concentrations completely prohibited germination during the five-week duration of the study. For the pot experiment, 25 mL application of OVW significantly delayed and reduced cheeseweed germination, with the reduction being proportional to the concentration of OVW. In the third experiment, composts reduced weed dry matter (composed mostly of purslane (Portulaca oleracea L.)), with the CR compost being the most effective, reducing total weed biomass by 67% compared to the control. CR10 and DM10 tended to increase bell pepper yields, although none of the plant parameters was significantly affected by the compost treatments.

Hydrogen enriched syngas production via gasification of biofuels pellets/powders blended from olive mill solid wastes and pine sawdust under different water steam/nitrogen atmospheres

In this work, we study the gasification of pellets produced, after densification, by blending olive mill solid wastes, impregnated or not by olive mill waste water, and pine sawdust under different steam/nitrogen atmospheres. The charcoals necessary for the gasification tests were prepared by pyrolysis using a fixed bed reactor. The gasification technique using steam was chosen in order to produce a hydrogen-enriched syngas. Gasification tests were performed using macro-thermogravimetric equipment. Tests were carried out at different temperatures (750 °C, 800 °C, 820 °C, 850 °C and 900 °C), and at different atmospheres composed by nitrogen and steam at different percentages (10%, 20% and 30%). Results show that the mass variation profiles is similar to the usual lingo-cellulosic gasification process. Moreover, the increase of temperatures or water steam partial pressures affects positively the rate of conversion and the char reactivity by accelerating the gasification process. The increase of the gasification yields demonstrates the promise of using olive mill by-products as alternative biofuels (H2 enriched syngas).

Effects of olive wastewater and pomace extracts, lecithin, and ascorbyl palmitate on the oxidative stability of refined sunflower oil

In this study, the effects of olive mill wastewater (OMW) and olive pomace (OP) extracts (1 and 2 mg/g), lecithin (L, 1–5 mg/g), and ascorbyl palmitate (AP, 0.2 mg/g) on the oxidative stability of refined sunflower oil (SFO) and its purified triacylglycerols (TAGs) were investigated under accelerated oxidation conditions. Induction period of TAGs increased from 6.84 to 11.27 hr, with OMW methanol extract (1 mg/g), while OP extracts provided less protection (9.79 hr) at 90°C in Rancimat. The K232 values of the SFO with extracts (1 mg/g) and AP (0.2 mg/g) was lower than those of butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and α-tocopherol containing oil samples at 60°C. Binary combinations of extracts with AP (0.2 mg/g) or L (5 mg/g) also effectively decreased the K232 and K270 values of TAGs during oxidation. In conclusion, OMW and OP extracts can be synergistically used with L or AP for stabilization of SFO against oxidation. Practical applications Generally, edible oils contain high amount of unsaturated fatty acids which are susceptible to oxidation during heat required food processes. Natural antioxidants are preferably used for increasing oxidative stability of edible oils. Olive mill byproducts contain valuable phenolic compounds that have high antioxidant capacity. In this study, we studied antioxidant efficiencies of the olive wastewater and pomace extracts in sunflower oil in combinations with lecithin and ascorbyl palmitate. These combinations can be successfully used to increase the oxidative stability of sunflower oil.

Efficient production of lignin-modifying enzymes and phenolics removal in submerged fermentation of olive mill by-products by white-rot basidiomycetes

The ability of seven distinct species of white-rot basidiomycetes (WRB) to produce lignin-modifying enzymes (LME) and reduce high phenolic content was assessed during submerged fermentation of oil mill by-products. Cerrena unicolor strains appeared to be the outstanding producers of laccase (56.3–78.5 U mL−1) and MnP (1.03–2.76 U mL−1) in the fermentation of olive pomace (OP), and laccase (26.9–93.8 U mL) in the fermentation of olive tree sawdust. Diluted 50% olive mill wastewater (OMW) can be used as a nutrient medium for laccase and MnP production but its supplementation with additional carbon and nitrogen sources and Cu2+ and Mn2= promoted the 3-, 28- and 18-fold increase of C. unicolor biomass and volumetric laccase and MnP activities, respectively, as well as 3- and 17-fold increase of Pleurotus ostreatus biomass and laccase activity, respectively. The tested fungi successfully reduced the phenolics content in the submerged fermentation of OP (72.0–81.3%) and OMW (62.4–83.5%). The laccase role in the OP phenolics reduction was proved through the treatment of 10% (wet weight) OP with commercial and lab-generated laccases preparations and reduction of total phenols by 66–70% during 24 h incubation. This work indicated that the olive mill by-products fermentation by individual substrate-specific WRB is an economically feasible and promising alternative for the simultaneous production of LME, cellulase, xylanase and detoxified materials suitable for further exploitation in biotechnological and agronomic applications.

Effect of addition of organic materials and irrigation practices on soil quality in olive groves

Abstract The effect of addition of organic materials (shredded pruning residues, composted olive mill by-products) on spatial distribution of soil chemical and microbial properties in irrigated and rainfed olive groves was investigated. Most of the soil parcels were subjected to reduced tillage or no tillage practices. Soil sampling took place in 40 olive groves in the region of Messinia, south-western Peloponnese, Greece during a 5-year period (2012–2017). The results showed significant increases in soil organic matter, humic acids and nitrate content at the end of the study period, compared to the first year of the soil sampling campaign. On the other hand, the relatively low amount of fresh organic materials that was applied to the soil produced unfavorable results. Differences between irrigated and rainfed soil parcels were not significant, for most of the soil properties, since the area receives much higher loads of rain than the average rainfall, as registered in the main olive growing regions of Greece. The area underneath the tree canopy favors an environment that enhances soil fertility, compared to the area out of the tree canopy. Changes of soil properties according to depth showed that the surface soil in olive orchards has the potential to sequester carbon and nutrients.

Toward an Increased Functionality in Oyster ( Pleurotus) Mushrooms Produced on Grape Marc or Olive Mill Wastes Serving as Sources of Bioactive Compounds.

Pleurotus ostreatus, P. eryngii, and P. nebrodensis were cultivated on nonconventional substrates containing grape marc (GMC) or olive mill byproducts (OMB); wheat straw (WHS) served as control. GMC-based media demonstrated equal/better mushroom productivity than WHS for P. eryngii and P. nebrodensis, while the cultivation performance of P. eryngii was improved in OMB-based media. Both GMC and OMB substrates led to large increase of fruit-bodies content in phenolic acids, resveratrol, triterpenic compounds, and ergosterol; in particular, P. eryngii mushrooms presented significantly more total phenolics and exhibited much higher antioxidant activity (2- to 8-fold increase). Furthermore, substrates containing GMC or OMB presented up to 27% increase in mushroom β-glucans. Overall, Pleurotus species responded in a different and mostly substrate-specific manner by selectively absorbing organic compounds. Phenolics and squalene content of substrates correlated very well with mushrooms antioxidant activity and ergosterol, respectively; the same was observed for triterpenics' content of substrates and mushrooms.

Direct and Rapid Profiling of Biophenols in Olive Pomace by UHPLC-DAD-MS

Olive mill by-products are effluents generated during olive oil production process. The two-phase centrifugation system produces a semi-solid olive pomace called “alperujo.” This by-product is a combination of liquid and solid wastes derived from the three-phase manufacturing process. A direct and fast analytical method by ultra-high-pressure liquid chromatography-DAD coupled with ESI/MS-MS has been developed for the profiling of phenolic compounds. Thirty-five metabolites belonging to phenyl alcohols, secoiridoids, flavonoids, and iridoids were identified as the main constituents of alperujo in 12 min, including p-coumaroyl aldarate and a verbascoside derivative found for the first time in alperujo and a new ligstroside derivative. Six quantitatively significant components were determined at concentrations ranging from 17.7 mg/L for p-coumaric acid to 370.7 mg/L for hydroxytyrosol. Our data confirm that alperujo is an interesting source of phenolic compounds that could be extracted for use as nutraceuticals.

Integrated biovalorization of wine and olive mill by-products to produce enzymes of industrial interest and soil amendments

An integral and affordable strategy for the simultaneous production of lignin-modifying and carbohydrate active enzymes and organic amendment, with the aid of a saprobe fungus was developed by using olive oil and wine extraction by-products. The polyporal fungus Trametes versicolor was cultivated in soy or barley media supplemented with dry olive mill residue (DOR) as well as with grape pomace and stalks (GPS) in solid state fermentation (SSF). This strategy led to a 4-fold increase in the activity of laccase, the principal enzyme produced by SFF, in DOR-soy media as compared to controls. T. versicolor managed to secrete lignin-modifying enzymes in GPS, although no stimulative effect was observed. GPS-barley media turned out to be the appropriate medium to elicit most of the carbohydrate active enzymes. The reuse of exhausted solid by-products as amendments after fermentation was also investigated. The water soluble compound polymerization profile of fermented residues was found to correlate with the effect of phytotoxic depletion. The incubation of DOR and GPS with T. versicolor not only reduced its phytotoxicity but also stimulated the plant growth. This study provides a basis for understanding the stimulation and repression of two groups of enzymes of industrial interest in the presence of different carbon and nitrogen sources from by-products, possible enzyme recovery and the final reuse as soil amendments.