1,721,060 research outputs found
Methylene blue adsorption using chabazite: Kinetics and equilibrium modelling
No full textThe adsorption of methylene blue from aqueous solution by a natural zeolite (chabazite) was studied. The effect of adsorbate concentration and pH were evaluated using raw and acid-treated chabazite. Fourier transform infrared spectroscopy analysis revealed surface modification of acid-treated chabazite, thus resulting in a decrease in adsorption capacity. The sorption kinetics and the equilibrium isotherms were evaluated. The pseudo-second-order model was found to be the most suited for kinetic results, and the Langmuir isotherm was chosen to better describe the sorption system. The results confirmed the efficacy of raw chabazite in removing almost all methylene blue fraction from the solution. The use of such a material, at low cost and easily available, can therefore represent a possible efficient way to remove dyes from effluent of many industries
The effect of citric acid on the phenolic contents of olive oil
No full textResponse surface methodology was used to optimise the combined effects of malaxation time (t) and
aqueous citric acid solution (CA) added at the beginning of the malaxation step on total polyphenols
(TP) and o-diphenols (OD) content and the antiradical power (ARP) of the olive oil extracted from the Italian
olive fruits of Coratina cultivar. Different tests were performed according to a 32 full factorial design,
varying t from 30 to 90 min and the CA from 5 to 15 ml/kgpaste. Overall optimal conditions identified by a
numerical optimisation for the three responses were found to be at t = 30 min and CA = 13.79 ml/kgpaste
under which the model predicted TP = 604.52 lgCAE/goil, OD = 80.44 lgCAE/goil and ARP = 28.73
lgDPPH/llextract. There were also linear correlations between TP (R2 = 0.8176) and OD (R2 = 0.8633) values
of olive oil and waste water. The results of this study demonstrate that considerably short malaxation
time and relatively small amounts of citric acid were required to enhance the quality of olive oil. The outcome
of our study will therefore be of great value for the commercial production of olive oil with high
level of polyphenols and o-diphenols
Effect of encapsulating agent on physical-chemical characteristics of olive pomace polyphenols-rich extracts
No full textDuring the last years, olive industry wastes are considered as a potential source of extracts with antioxidant properties rich in polyphenols. The recovery of these added-value compounds can be interesting both for their beneficial properties and from an environmental point of view and several studies have been performed for the optimization and characterization of the phenolic compounds present in olive pomace liquid extracts. However, dried forms of natural extracts are associated with several advantages over liquid forms, such as limited storage costs, higher concentration and stability of target compounds. Spray drying is one of the most common techniques for the transformation of a liquid extract, or food formulation, into dried powder, due to low operative costs respect to other methods, and high flexibility, related to the large number of operative parameters that can be optimized, such as coating agent type and concentration, inlet temperature, feed flow and aspiration rate. In this study, an ethanolic extract rich in phenolic compounds from olive pomace (Taggiasca cultivar) was obtained by high pressure and temperature extraction and spray dried with different ratios of gum Arabic and maltodextrin as coating agents (0:100, 20:80, 40:60, 60:40, 80:20 and 100:0 % w/w). The total amount of coating agent was maintained constant and equal to 10 % w/v (100 g/L). Inlet temperature, feed flow and aspiration rate were 160 °C, 5 mL/min and 30 m3/h, respectively. For all products, moisture content, water solubility index, total polyphenol content, antiradical power and microencapsulation yield were determined. The results of this study show that the coating agent and process conditions led to the production of microencapsulated powders with improved water dissolution rate and a minimal loss in phenolics during the drying phase. The obtained microparticles, due to their high content in bioactive compounds and ease of handling, can have potential industrial applications as functional components for foods or nutraceuticals purposes
Small diameter vascular grafts coated with gelatin
No full textIn the field of tissue engineering, there is an increased demand for small diameter vascular grafts to treat peripheral vascular pathologies and ischemic heart diseases. The limited availability of suitable autogenous veins and the drawbacks related to the use of synthetic materials, such as polyethylene terephthalate (Dacron®) and expanded polytetrafluoroethylene (ePTFE), especially when they are used as substitutes for small diameter vessels, have attracted several investigators turning their attention toward the fabrication of alternative biocompatible grafts. In this study, small diameter tubular grafts (2 mm), made of poly (Ïμ-caprolactone) (PCL) and poly (glycerol sebacate) (PGS) at a ratio of 1:1 (v/v) were obtained by electrospinning. With the aim to reduce water permeability, their surface was modified by dynamic coating of gelatin at 37 °C for 1 h, followed by UV-irradiation. Thickness, fiber diameters, porosity, mass loss, fluid uptake, water permeability, gelatin release, mechanical properties, cytotoxicity, and hemocompatibility of gelatin-coated electrospun scaffolds (GCS) were studied and compared with uncoated scaffolds (UCS). Scanning electron microscopy (SEM) images showed that the gelatin surface modification did not affect the 3D structure and pore interconnectivity of the scaffolds. A significant decrease in the water permeability was noticed when gelatin was used as coating agent. The results of this study highlighted the importance of a very low cost surface treatment with gelatin to improve the properties of PCL:PGS electrospun grafts. In conclusion, these gelatin-coated prostheses could be considered as a good candidate for vascular replacement in tissue engineering
Optimisation of olive oil extraction by means of enzyme processing aids using Response Surface Methodology
No full textThe aim of the present work was to optimise the oil extraction process of the Italian olive fruits of Coratina cultivar using a previously selected enzyme formulation
Chlorella vulgaris growth on digested urban sludge
No full textThe aim of this research was to investigate the effect of the addition of digested urban sludge on the growth medium of the microalga Chlorella vulgaris. The anaerobic digestion of biomass feedstock and/or the biodegradable fraction of wastes is widely recognized as a mature and cost-effective process for producing biogas, which is a valuable renewable primary-energy source. Anaerobically digested residues are effluents still rich in inorganic nutrients, with high chemical oxygen demand, which contribute to the eutrophication phenomenon. It is therefore necessary to further treat the effluent. Microalgae could potentially offer many advantages being able to use the organic carbon (heterotrophic growth) as well as inorganic nutrients such as nitrogen and phosphorus from the wastewater for their growth without an aerobic environment. In this study, an anaerobic digester (2.5 L), placed in a thermostatted water bath under mesophilic conditions (38 ± 1 °C) and pH 7.2–7.4, was employed. The mixed sludge (1.25 L) was daily fed with 30 mL of urbane sludge. Under pseudo-steady state conditions, the composition of biogas was nearly constant, and methane and carbon dioxide percentages ranged between 70.5–76.0 % and 13.2–19.5 %, respectively. The digested sludge was removed daily and centrifuged. The liquid phase was added in different percentages (100, 66 and 33 %) into the C. vulgaris medium to perform batch cultivations. The microalga concentration at the end of the experiments reached 2.72, 2.34 and 1.22 g/L when 66, 33 and 100 % of digested sludge liquid phase were used, respectively. These preliminary results suggest that combining microalgae production with municipal wastewater treatment could be made in an environmentally effective as well as economically viable way in a not distant future
UV-VIS spectroscopy for monitoring yogurt stability during storage time
No full textColor, texture and taste are key elements of a consumer's buying decision; thus, monitoring the stability of these features throughout the entire period of yogurt validity is fundamental for dairy product producers. Color, texture and taste deteriorations are due to changes in the physical, chemical and microbiological compositions of yogurt and they can be monitored using lab analyses (especially the microbiological ones) which are expensive and time consuming. In this study, ultraviolet-visible (UV-VIS) spectroscopy was applied as a rapid and alternative technique to traditional analytical methods, to monitor the stability of different commercial yogurt samples up to 49 days of storage at 4 °C. UV-VIS spectroscopy was employed with an integrating sphere for diffuse reflectance measurements and, for each yogurt, color stability during storage time was evaluated in terms of CIEL∗a∗b∗ color space values. Moreover, Partial Least Squares regression combined with Genetic Algorithms (GA-PLS) was performed for predicting the age of the yogurt samples from their UV-VIS spectra. In order to evaluate the texture and taste changes, flow curves and pH values of yogurt during storage were monitored once a week for the entire considered storage period. The UV-VIS and rheological datasets were elaborated by means of univariate and multivariate methods. It was interesting to notice that, in both datasets, the time-related information was not visible by simply comparing the profiles of signals, poorly visible in the principal component space, and clearly explained by three-way Principal Component Analysis (3-way PCA)
Production of chocolate powdered beverage with enhanced instant properties
No full textInstant properties of chocolate powder such as solubility and dispersibility are important factors for the quality and consequently consumer acceptance of the final powdered beverage. With the aim of producing a novel powdered chocolate beverage with enhanced instant solubility, we studied the effect of spray drying process on the components of the chocolate powder. Spray drying of chocolate beverage formulation (complete recipe provided and protected by Domori s.r.l., Italy) was performed using a mixture of cocoa powder and sucrose 30:70 (w/w). Liquid feed was prepared by dissolving 17.5 g of powder in 100 mL of deionized water at 60 °C and mixed until complete homogenization. The solution was fed to a mini spray dryer B-290 (Büchi, Huddersfield, UK). In this work an inlet temperature of 150 °C was used. Maltodextrin concentration (0, 3.5 and 7 % w/w) and drying air flow rate (22, 27 and 32 m3/h) were varied. Powders were stored at 4 °C in closed dark vessels before analysis. The results of full factorial design showed that operating at a drying air flow rate of 27 m3/h and a maltodextrin concentration of 3.5 % w/w, powder with solubility of 74.2 ± 6.8% and dispersibility of 58.7 ± 2.9% was achieved. At this operative condition, powder recovery yield was almost consistent with the industrial one (45.5 ± 2.5%). Therefore, spray drying presents a useful way to produce chocolate powder with better instant solubility, which can also be dissolved in less amount of water (70 mL instead of 120 mL)
Use of Supercritical Assisted Atomization to produce nanoparticles from olive pomace extract
No full textOlive pomace is one of the most interesting wastes containing bioactive compounds; the extraction of polyphenols can represent an innovative solution for the reduction of the environmental hazard of this solid and the simultaneous recovery of high-added value compounds. In this study, Supercritical Assisted Atomization (SAA) was employed for the encapsulation in maltodextrin of phenolic compounds extracted from olive pomace. The effect of the ratio of maltodextrin content to total solid content of the extract and drying temperature on physical characteristics, total phenolic content and antioxidant properties of the powdered product were studied. The results confirmed the efficiency of the SAA process to encapsulate phenolic compounds from olive pomace extract. Particles with average diameter of 712 nm with high total polyphenol content (105.0 ± 0.1 mgCaffeic Acid Equivalent/gDry Powder) and antiradical power (98.8 ± 3.0 mgDPPH/mLextract) were obtained. These particles rich in bioactive compounds can be used as functional component in formulations of new food, cosmetic or pharmaceutical products. Industrial relevance Olive pomace is considered to be a low-cost and renewable source of high-added value compounds, such as polyphenols which can be valorized by several methodologies. In this work, we assessed the efficiency of Supercritical Assisted Atomization (SAA) in order to encapsulate phenolic compounds extracted from olive pomace. The particles obtained by SAA have spherical morphology with average diameter of 712 nm. The polyphenol-rich nanoparticles produced using this technique can be potentially used in the formulation of novel food or nutraceutical products
Micro-modelling of IT-SOFC electrodes manufactured through electrospinning
No full textInfiltrated electrodes for intermediate temperature-solid oxide fuel cells (IT-SOFCs) are currently the subject of intense research. Focusing on electrodes with a fibrous microstructure typically obtained through the electrospinning technique, we analyze the role of infiltrations from a modelling point of view. The model includes the evaluation of i) charge transfer reaction occurring at the dopant particles and, possibly, at the electrode/electrolyte interface; ii) electron and/or oxygen-ion conduction along the fiber, and iii) additional charge conduction along the dopant nano-particles, if percolating occurs throughout the electrode structure. The model is applied to doped anodes and cathodes, considering infiltration loadings below and above the percolation threshold. The model allows evaluating the overall reciprocal electrode resistance 1/Rp and the electrochemically active thickness (EAT). Simulation results demonstrate good agreement with literature experimental data
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