1,721,082 research outputs found
Modelling of polyphenol recovery from olive pomace by response surface methodology
No full textFactorial design and Response Surface Methodology (RSM) were used to model the
recovery of polyphenols from olive pomace (OP) by solvent extraction. Experiments carried out
according to a Central Composite Design (CCD) allowed evaluation of the effects of temperature
(T), extraction time (E), solvent composition (C) and liquid-to-solid ratio (R) on the yield of
polyphenol extraction. Statistical analysis of the results showed that T was the most influential
factor, followed by E, R and C. A reduced polynomial model was developed by the stepwise
regression method. The model was checked by performing validation experiments both inside and
outside the factorial region. A very good agreement was observed between experimental and
calculated extraction yields, thus supporting the use of the model to quantitatively describe the
recovery of polyphenols from OP
Response surface methodology analysis of polyphenol recovery from artichoke waste
No full textLarge amounts of a solid waste consisting mainly of outer bracts and stems are produced from the industrial processing of artichokes. In this study, the recovery of polyphenols from the two waste components was investigated. Extraction experiments were carried outby an environmentally friendly procedure using aqueous ethanol as solvent. The total polyphenol content, expressed as mg of GAE per g of dry weight, was 10.23±0.68 mg/g for bracts and 16.36±0.85 mg/g for stems. To evaluate the effect of Temperature (T), Extraction time (E) and liquid-to-solid Ratio (R) on the extraction yields, a central composite design coupled with response surface methodology was used. Under the best conditions (T = 50°C, E = 110.4 min and R = 20 mL g-1), extraction yields between 90 and 93% were obtained. Statistical analysis of the data showed that E was the most influential factor, followed by T and R. Simplified polynomial models were developed to describe the effect of individual factors and their interactions on the extraction yield of polyphenols. Overall, the results of this study support the potential of using artichoke waste as a source of natural phenolic antioxidants and give useful directions on how to improve recovery by proper selection of extraction conditions. © 2014 Science Publication
Optimization of polyphenol recovery from espresso coffee residues using factorial design and response surface methodology
No full textBackground and objectives: From the production of instant coffee or espresso beverages a solid waste known as spent coffee grounds (SCG) is generated. SGC are a rich source of antioxidant compounds, mainly polyphenols, which can be easily recovered by solvent extraction. However, little attention has been paid to investigating the extraction process in a systematic way. In this study, a rigorous approach based on response surface methodology is used to optimize the recovery of polyphenols from SCG and to evaluate the properties of the dry phenolic extracts obtained under optimal process conditions. Methods: Polyphenols were recovered from SCG by an extraction procedure using aqueous ethanol as the solvent. A central composite design coupled with response surface methodology was used to evaluate the effect of temperature (T = 20-60 °C), extraction time (E = 30-150 min), liquid-to-solid ratio (R = 10-50 mL/g) and ethanol concentration in the solvent (C = 10-90 vol%) on the extraction yield (y). A mechanically-stirred extractor operated under optimized conditions was used to obtain dry phenolic extracts. Results: All the factors examined had a positive effect on polyphenol recovery, with T and R being the most influential. The following optimal conditions were found: T = 47.1 °C, E = 150 min, R = 47.98 mL/g and C = 57.7%, with ymax = 97.8%. The antioxidant activity of the dry phenolic extract, determined by the ABTS assay and expressed as Trolox equivalents (TE), was 1583 ± 57 μmol TE/g. Conclusions: The obtained results show that SCG from the production of espresso coffee beverages are a rich source of polyphenols. High extraction efficiencies can be achieved by optimization of the extraction process, which can be used to produce dry phenolic extracts with very high antioxidant activity
Recovery of flavonoids from three-phase olive pomace by aqueous ethanol extraction
Full text linkA three-phase olive pomace (OP), the solid by-product originating from the production of olive oil, was investigated as a potential source of flavonoids. Flavonoids were extracted by an environmentally friendly procedure using aqueous ethanol as solvent. The flavonoid content of OP, expressed as quercetin equivalents (QE) per unit weight of dry material, was 25.28 ± 0.93 mg QE/g. To evaluate the effects of temperature (T), extraction time (E), liquid-to-solid ratio (R) and solvent composition (C) on the yield of flavonoid extraction (y), a Central Composite Design (CCD) coupled with Response Surface Methodology (RSM) was used. Statistical analysis of the results showed that T was the most influential factor, followed by E, R and C. A reduced polynomial model was developed by the stepwise regression method which provided an accurate description of the extraction process. Maximization of the response variable gave: ymax = 90.5% at T = 69.9 °C, E = 212 min, R = 36.7 mL/g and C = 43.7%. Overall, the obtained results support the use of three-phase OP as a source of flavonoids and give useful indications on the influence of process variables on their recovery
Preparation and characterization of magnetically responsive biosorbents from coffee industry residues
No full textSpent coffee grounds (SCG) and coffee silverskin (CS), the two main coffee industry residues, were magnetically modified by contact with an aqueous ferrofluid containing magnetite nanoparticles. The materials were characterized by SEM-EDX analysis, X-ray diffraction and FTIR spectroscopy. Batch adsorption experiments were performed to assess their suitability as biosorbents, using methylene blue as a model pollutant. Adsorption equilibrium data were analysed by the Langmuir model, which allowed estimation of the maximum adsorption capacity. The magnetic biosorbents were easily regenerated by treatment with hydrochloric acid. © (2013) Trans Tech Publications, Switzerland
Improved lycopene extraction from tomato peels using cell-wall degrading enzymes
Full text linkFour commercial enzyme preparations with pectinolytic, cellulolytic and hemicellulolytic activities were tested for their ability to enhance lycopene extraction from tomato peels. Screening experiments were performed at 25 degrees C by subjecting the peels to a 4-h enzyme incubation followed by 1-h hexane extraction. Peclyve EP and LI were the most efficient, with an almost 20-fold increase in extraction yield. Peclyve LI was used to evaluate the influence of solvent type and enzyme incubation time on lycopene recovery. Hexane, ethyl acetate and the mixture hexane/acetone/ethanol 50:25:25 (v/v) were used as solvents. Under the best extraction conditions (1-h enzyme incubation followed by a 3-h solvent extraction at 40 degrees C) up to 440 mg of lycopene per 100 g of dry tomato peels were obtained. The percentage recoveries were in the range of 3-30%, for the untreated peels, and 77-98% for the enzymatically treated material
Stability and degradation kinetics of lycopene in vegetable oils
Full text linkThe stability of lycopene in sunflower seed oil (SSO), grape seed oil (GSO) and rice bran oil (RBO) was investigated in the temperature range of 10-40 °C. Kinetic analysis of lycopene degradation showed that the process is first-order with respect to the carotenoid concentration, with apparent activation energies between 50.8 kJ mol-1 (RBO) and 70.0 kJ mol-1
(GSO). The half-life of lycopene in the oils was dependent on the storage temperature and varied from 303 to 530 days, at 4 °C, and from 86 to 104 days, at 20 °C. Below 15-20 °C, stability increased in the order: RBO < GSO < SSO, while at higher temperatures such differences tended to disappear. This is likely due to the combined effects of endogenous antioxidants and
unsaturated triacylglycerols in the oils on the degradation pathway of lycopene.
2011 Praise Worthy Prize S.r.l. - All rights reserved
Chloramphenicol removal from wastewater by UV/H2O2 advanced oxidation process
No full textThe efficacy of the UV-H2O2 treatment to degrade the antibioticchloramphenicol (CHL) was investigated at 20°C using a low-pressure mercury lamp as UV source. A two-level factorial design was used to study the effects of initial CHL(c0 = 40-80 mg L-1) and H2O2(h0 = 20-50mM) concentrations, reaction time (t = 30-70 min) and irradiance level (I = 400-800 μW cm-2) on CHLdegradation. Under the best conditions (c0 = 40 mg L-1, h0 = 20 mM, t = 70 min, I = 800 μW cm-2), almost 96% of the antibiotic was degraded. No residual antibiotic activity was detected in the treated solution, thereby confirming the efficacy of the UV-H2O2 process. © (2013) Trans Tech Publications, Switzerland
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