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•Microwave pyrolysis of olive pomace was investigated.•Optimal processing conditions were determined to be 200 W for 180 s.•Energy requirement of 3.6 kJ/g pyrolysed 80% of OP and ...yielded 30% bio-oil.•Microwave power influenced textural and adsorption properties of bio-chars.•Bio-oils contained a high abundance of acetic acid.
Olive pomace is a widely available agro-industrial waste residue in Europe that has the potential to contribute towards a circular, low carbon bio-economy. This study demonstrated, for the first time, the ability to successfully pyrolyse olive pomace with microwaves for the production of bio-char and bio-oil. It was found that the energy requirement needed to pyrolyse up to 80% of the olive pomace was as low as 3.6 kJ/g and bio-oil yields up to 30% were produced. Microwave power did not influence the overall yields or the chemical composition of the obtained bio-oils, but did alter the textural properties of the generated bio-chars and their ability to remove methylene blue dye. Optimum processing conditions were found to be within the 3.6 kJ/g energy requirement with a microwave power of 200 W and processing time of 180 sec. These conditions produced a bio-oil fraction containing mainly acetic acid (71.9%) and a bio-char with a surface area of 392.3 m2/g, micropore volume of 0.15 cm3/g and a methylene blue removal efficiency of 40 qMB mg/g. The results acquired from this study reveal the superiority of microwave heating in a pyrolysis system and highlight a novel and prospective route for added value recovery from natural waste resources like olive pomace.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study fortified pasta was prepared through the replacement of durum wheat semolina with 0, 5 and 10 g/100 g of olive pomace (OP). OP was characterized by high total phenolic compounds (TPC) ...and a significant amount of fibre. Fortification with OP significantly increased the TPC and the antioxidant capacity, both in cooked and uncooked pasta. OP incorporation decreased the optimum cooking time while increasing the swelling index, the water absorption and the cooking loss. Firmness significantly increased with increasing levels of OP as well as the adhesiveness. OP incorporation affected the starch fractions, reducing the rapidly digestible starch and increasing the slowly digestible starch and the resistant starch, without significantly influencing the predicted in vitro glycaemic index. These results show that pasta fortified with OP could represent a healthy product and a potential technological alternative for the food industry by-products re-use.
•Olive pomace are high in total phenolic compounds and dietary fibre.•Pasta fortification with olive pomace powder was developed.•Olive pomace enhanced pasta total phenols and antioxidant capacity.•Olive pomace increased cooking loss, swelling index and water absorption.•Addition of olive pomace effects the starch digestibility of pasta.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The olive pomace (OP) is an underutilized byproduct from the olive oil extraction that has the potential to be used as a source of antioxidant phenolics for nutraceutical applications. The ...simultaneous use of enzymes (cellulase, pectinase, and tannase) and microwave processing was evaluated with respect to OP phenolic extractability and composition. Microwave-assisted extraction achieved similar phenolic extractability (272 mg GAE/g OP) to conventional solvent extraction using water as a solvent, a higher solids-to-liquid ratio (1:15 vs. 1:50, g/mL), and a shorter reaction time (17 vs. 120 min). The use of enzymes during microwave processing led to increased extractability of phenolics (341 mg GAE/g OP) at higher extraction temperature (60 °C) and faster heating strategy (5 min ramp time). Microwave-enzyme-assisted extraction and enzyme-assisted extraction produced phenolic extracts with a higher concentration of phenolic alcohols (22–48 mg/kg) and acids (including hydroxytyrosol) (17–26 mg/kg). Mixtures of pectinase, cellulose and tannase biotransformed OP phenolics thus leading to the production of elenolic acid at 1029 mg/kg.
•Microwave processing achieved higher phenolic extractability in shorter reaction times.•Microwave heating intensified enzyme activity and phenolic extraction.•Pectinase, cellulase and tannase biotransformed oleuropein into elenolic acid.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•9 commercial membranes were tested for OSN of extracts from wet olive pomace.•Industrially interesting phenolic compounds can be recovered by OSN.•High purification of valuable ...hydroxytyrosol and tyrosol has been achieved.•Molecular weight is not enough to predict rejection values in OSN.
Organic-solvent nanofiltration (OSN) has been applied to purify and fractionate the phenolic compounds present in wet olive pomace, which is the main by-product of olive mills. Nine commercial OSN membranes have been tested: DuraMem® 150, DuraMem® 300, DuraMem® 500, PuraMem® 600 (Evonik), NFS, NFX (Synder), oNF-1 and oNF-2 (Borsig) and NF270 (FilmTec). Their stability in ethanol/water 50:50 (v/v) and their effectiveness to treat a model solution of a solvent-based extract of wet olive pomace have been studied. To that end, a METcell cross-flow system (Evonik) has been utilized. DuraMem® 500, NFX and NF270 membranes displayed satisfactory values of permeate flux (10–100 L·h−1·m−2) compared to the other tested membranes. Measurements of the contact angle of the membranes after their conditioning and after the nanofiltration process allowed the comprehension of the interaction between the ethanol/water 50:50 (v/v) solution and the membrane. The solvent contact angle was also examined. AFM was employed to understand the modification of membrane morphology. To characterize the samples, liquid chromatography coupled to mass spectrometry (and/or refractive index detector) was employed. The selected membranes exhibited low rejection values for the aimed phenolic compounds (less than 10 % for hydroxytyrosol) and high rejection (50–100 %) of the undesired compounds, such as sugars and organic acids. Therefore, the purification of the target phenolic compounds was accomplished.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Olive pomace is an environmentally harmful waste from the olive oil industry, containing large amounts of bioactive compounds that could be used in several areas. In the present study, the olive ...pomace, by-products, was fractionated successively using organic solvents of increasing polarity (cyclohexane (CYHA), ethanol (EtOH) and distilled water) to determine their biochemical composition (total phenolic content, total flavonoid content, HPLC, and GC-MS) and biological activities (antioxidant and antibacterial activities). In addition, the olive pomace was extract directly by the distilled water to determine its physicochemical characteristics (pH, humidity and quantity of oil). The study proved that olive pomace has a low content of total phenolic content in the three extracts (from 0.81 to 2.24 mg GAE/g dry residue). Likewise, for the content of total flavonoids, it presents in the CYHA and EtOH extracts of 0.5 and 0.4 mg QE/g dry residue, respectively. GC-MS data showed the detection of 6 volatile compounds in the cyclohexane extract which contains two major compounds were hexadecanoic acid (2.23%) and 9-octadecenoic acid (8.67%). Moreover, HPLC data showed that chrysin compound was the major one among the four detected ones in the organic extracts of olive pomace. The results showed that the CYHA extract exhibited the best antioxidant power exceeds 50% on the other hand, it is less than 25% for the ethanoic and aqueous extract. In the aqueous extract there is a stronger antibacterial activity against the strain L. monocytogenes (13 mm) than the reference (ampicillin) and the bacterial strain B. cereus (11 mm) associated with their phenolic activity.
Liquid-enriched powder (LOPP) and pulp-enriched powder (POPP) obtained from olive pomace were incorporated into yoghurt, not only, to increase its content in dietary fibre, hydroxytyrosol and ...unsaturated fatty acids, but also to understand the lipids-phenolics interaction by simultaneous incorporation of olive oil. POPP (2%) and LOPP (1%) addition to yoghurt allowed fulfilling the condition of being a “source of fibre” and provided 5 mg of hydroxytyrosol and derivatives in a standard yoghurt (120 g), respectively. Yoghurts’ unsaturated fatty acids profile was positively influenced by the addition of only POPP and olive oil + LOPP or + POPP. All OP powder-fortified yoghurts exhibited higher total phenolic content and antioxidant activity than the control (p < 0.05). After in vitro digestion the bioaccessibility of total phenolics (more 25.58%) and hydroxytyrosol (more 68.71%) in LOPP-yoghurts was improved by the addition of olive oil. In conclusion, OP powderś incorporation gave additional and essential healthy properties to yoghurt.
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•Powders obtained from olive pomace exhibited potential as food ingredients.•Yoghurt with POPP (2%) fulfilled the nutritional claim “source of fibre”.•LOPP (1%) provides 5 mg of hydroxytyrosol and derivatives in a standard yoghurt.•POPP and olive oil addition enhanced yoghurts' profile.•Olive oil addition improved the hydroxytyrosol bioaccessibility in LOPP-yoghurts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•CO2 capture was performed using a low-cost adsorbent.•Olive pomace biochar was activated with KOH.•The adsorption capacity increases from 17 to 40 mg CO2/g biochar.•CO2 desorption ...was easily achieved at 60 °C.•The efficiency of biochar remains constant after five cycles of use.
The capture of CO2 directly from the air is one of the most promising methods under investigation in recent years to reduce the environmental concentration of this pollutant in order to mitigate its effects on climate change. In this work, the activation of olive pomace biochar with potassium hydroxide, KOH, has been studied for its use as a CO2 adsorbent. The effectiveness of biochar activated with KOH at 750 °C in an inert N2 atmosphere was evaluated, using different mass ratios of biochar/KOH, 1:0.5, 1:1, and 1:2. Various characterisation analyses of the biochar were performed to determine its chemical composition, specific surface area, pore size and volume, structure, morphology, and functional groups. The adsorption isotherm was determined at atmospheric pressure and a temperature of 10 °C. The experimental equilibrium results were fitted to the Langmuir, Freundlich, and Temkin models. Additionally, the kinetic behavior of biochar/KOH as an adsorbent was studied, and dynamic experiments were conducted at atmospheric pressure and 10 °C. The experimental data were fitted to various kinetic models (pseudo-first order, pseudo-second order, Avrami, and Elovich). Furthermore, the mass transfer mechanism during the adsorption process was evaluated using the intra-particle diffusion model. Finally, biochar regeneration was investigated for its subsequent reuse as an adsorbent. For this purpose, complete desorption of the captured CO2 in the biochar was easily carried out by modifying the temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Environmentally friendly polyphenolic extracts from grape and olive pomace were prepared.•Food by-products extracts possess antioxidant activity related with its polyphenolic content.•Extracts ...obtained by NADES have antiproliferative activity toward cancer cell lines.•Grape pomace is a source of DNA and RNA active compounds.•Extracts prepared with NADES probably could be used in products for human consumption.
To establish environmentally friendly polyphenolic extracts from grape and olive pomace, natural deep eutectic solvents (NADES) were used coupled with alternative energy sources – ultrasound and microwave irradiation. Obtained extracts were characterized by HPLC analysis, while antioxidant capacity was determined by ORAC method. Furthermore, in vitro cytotoxicity of prepared extracts was assessed by antiproliferation assay on two tumour cell lines, whereas for investigation of type of cell death or cell cycle arrest a flow cytometric analysis was applied. In addition, a detection of compounds with DNA/RNA-bindingaffinity in extracts was investigated by UV/Vis and circular dichroism spectroscopy. Grape pomace extract in NADES showed to be the best of all extracts tested, with regard to extraction of total polyphenolic compounds (p < 0.05) and related biological activities such as antioxidant and antiproliferative activity. Prepared polyphenolic extracts in NADES could be considered as ready-to-use in food and pharmaceutical industry without demanding and expensive downstream purification steps.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Olive pomace is a waste produced by the olive oil industry in massive quantities each year. Disposal of olive pomace is difficult due to high concentrations of phenolic compounds, which is an ...environmental concern. However, phenolic compounds have applications in the health industry. Therefore, extraction of phenolic compounds from olive pomace has the potential to remove an environmentally hazardous portion of pomace while creating an additional source of income for farmers and producers. Using advanced technologies including Ultrasound Assisted Extraction (UAE), combined with water as an extraction solvent, has recently gained popularity. The present study outlines the optimal UAE conditions for the extraction of phenolic compounds with high antioxidant activity from olive pomace. Optimal conditions were developed using RSM for parameters power, time and sample-to-solvent ratio. Total phenolic compounds determined by Folin Ciocalteu method and total major bioactive compounds determined by HPLC as well as antioxidant capacity (DPPH and CUPRAC) were investigated. The optimal conditions for the extraction of phenolic compounds with high antioxidant activity were 2 g of dried pomace/100 mL of water at 250 W power for 75 min. UAE improved the extraction efficiency of water and yielded extracts with high levels of phenolic compounds and strong antioxidant activity.
•The polluting effluent, olive pomace, is commonly dumped in landfill.•Novel method for extraction of phenolic compounds with high antioxidant capacity.•Water was used as an extraction solvent.•Ultrasound increased the phenolic compounds in the extracts by >20%.•Antioxidant activity of the extracts increased by >10%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The inclusion of crude and acid oils from olive pomace can lead to more unsaturated meat products and, especially in the case of olive pomace acid oil, achieve a more economically and environmentally ...sustainable swine production. The objective of this trial was to study the effect of dietary supplementation with crude and acid oils from olive pomace, which are rich in monounsaturated fatty acids (FAs) and have differing free FA content, on growth performance, digestibility, carcass parameters and FA profile of Longissimus muscle (LM) and backfat in growing-finishing pigs compared to the conventional crude palm oil. A total of 224 male and female pigs (Landrace × Large White) × Duroc were randomly distributed into 48 pens according to initial BW (58.7 ± 9.71 kg, mean ± SD) and sex. Four experimental treatments were randomly assigned (n = 12 pens/treatment; 4–5 pigs/pen) for the growing (0–42 days) and finishing (40–62 days) phases. Treatments consisted of a basal diet supplemented with 5% (as-fed basis) palm oil (PO), olive pomace oil (O), olive pomace acid oil (OA) or a mixture (M) of PO and OA at 50/50. No differences were found in the growth performance results between PO, O or M, but animals fed OA showed a lower gain to feed ratio than M (P = 0.008). No differences were found in apparent ileal digestibility among treatments, however, animals fed O and OA showed the highest values of total FA apparent total tract digestibility, while those fed PO had the lowest values, and M had intermediate values (P < 0.001). No differences were observed in carcass composition among treatments. In relation to backfat and the LM FA profile, O and OA treatments led to a higher unsaturated FA to saturated FA ratio and a lower content in saturated FA than PO. Moreover, O showed a higher intramuscular fat (IMF) content in LM than PO (P = 0.037). It is concluded that olive pomace oil is an interesting alternative fat source that can be included at 5% in growing-finishing pig diets, leading to meat products with more IMF, rich in monounsaturated FA, reaching high FA digestibility values and good pig performance parameters. Alternatively, olive pomace acid oil blended with conventional palm oil did not negatively impact fat utilisation nor performance. Including these fat by-products reduced feeding costs and led to a more efficient and environmentally sustainable production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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