Assessment of the olive oil extraction plant layout implementing a high-power ultrasound machine

The objective of this study is to assess the effects of installation and operation of a high-power ultrasound machine (HPU) for the treatment of olive paste by using ultrasound technology in order to evaluate the best way installation and the best definition of the operating conditions of the machine. The study was conducted installing in an industrial olive oil mill a continuous processing ultrasound machine, which used a frequency of 20 kHz able to work at 3200 kg h⁻¹ as feed capacity. Checking of performance has been carried out by the assessment of the different operating and process conditions, assessing in particular the impact of the ultrasound treatment before and after the malaxation phase on performance indicators of the continuous olive oil plant (plant extractability, olive paste rheological characteristic) and on selected chemical properties of the olive oil extracted (quality parameters, antioxidant content, and volatile profiles). In the tested conditions, high-power ultrasound treatment did not produce significant effect on the legal parameters (free acidity, peroxide index and spectrophotometric indexes), while a significant increase in the content of phenolic compounds was generally observed; higher enhancements were more evident when the high-power ultrasound treatment was carried out before the malaxation phase.     

Influence of bleaching by ultrasound on fatty acids and minor compounds of olive oil. Qualitative and quantitative analysis of volatile compounds (by SPME coupled to GC/MS)

The effects of bleaching using high power ultrasound (20 kHz) on the quality of olive oil were considered in this study, in order to verify the modifications that can occur in fatty acid composition and minor compounds. During the treatment of olive oil under ultrasonic waves, a rancid odour has been detected. Treated olive oils show no significant changes in their chemical composition but the presence of some volatile compounds, due to ultrasonic treatment. Some off-flavour compounds (hexanal, hept-2-enal and 2(E),4(E)-decadienal) resulting from the sonodegradation of olive oil have been identified. A wide variety of analytical techniques (GLC, HPLC and GC/MS) were used to follow the quality of bleached olive oils with ultrasonic waves by the determination of the amounts of certain minor compounds such as sterols and tocopherols. Steradienes, resulting from the dehydration of sterols, were detected with small quantities especially in severe conditions of sonication. Solid phase micro-extraction (SPME) coupled to gas chromatography was known to be a sensitive technique to follow changes in the oxidative state of vegetable oils by measuring the amount of volatile materials produced during the refining process.     

Working towards the development of innovative ultrasound equipment for the extraction of virgin olive oil

Malaxation has been recognized as one of the most critical points in the mechanical extraction process for virgin olive oil (VOO). It is a low and continuous kneading of olive paste at a carefully monitored temperature. Through this essential technological operation the small droplets of the oil formed during the milling merge into large drops that can be easily separated with a decanter centrifuge. During this technological phase, a complex and necessary bioprocess takes place in order to determine the quality and composition of the final product. The malaxer is a heat exchanger characterized by a low overall heat transfer coefficient because the ratio of surface area to volume is disadvantageous, so it is important to find an innovative technology to improve heat-exchange. As matter of fact, the malaxing step is the only discontinuous phase in a continuous extraction process. In the next future, the essential challenge of VOO industrial plant manufacturing sector is to design and build advanced machines in order to transform the discontinuous malaxing step in a continuous phase and improve the working capacity of the industrial plants. In order to reduce the malaxing time enhancing the quality of the product, two ultrasound-assisted virgin olive oil extraction processes were tested against the traditional method. The sonication treatment was applied on olives submerged in a water bath (before the crushing) and on olive paste (after the crushing). The ultrasound technology provides a reduction of the malaxing duration improving VOO yields and its minor compounds content. Better extractibility and higher minor compounds contents were obtained by sonicating the olives submerged in a water bath than olive paste. After experimental trials the results were employed to suggest innovative scaling up solutions of the process and new applications of ultrasounds in the VOO industry.     

The ultrasound application does not affect to the thermal properties and chemical composition of virgin olive oils

In this work, the effects of high power ultrasound treatment (40 kHz) on virgin olive oil (VOO) for different times (0, 15, 30 min) were studied, in order to verify if extent modifications in their chemical composition and thermal properties. The effects of the different ultrasound treatments on VOOs were determined considering the following parameters: quality index (free acidity, K₂₃₂ and K₂₇₀), lipid profile (fatty acids and triglycerides composition) minor components (phenols, tocopherols, pigments and volatiles) and thermal properties (crystallization and melting) by Differential Scanning Calorimetry (DSC).During the ultrasound treatments, bubbles growth was present in the VOO due to the phenomenon of cavitation and a slight increase of the temperature was observed. In general, the ultrasound treatments did not cause alterations on VOO parameters evaluated (oxidation state, lipid profile, minor components and thermal profiles). However, a slight decrease was observed in some volatile compounds.     

Inhibitory activity and conformation changes of soybean trypsin inhibitors induced by ultrasound

The inhibitory activities, sulfhydryl bonds and far-UV circular dichroism (CD) spectra of Kunitz and Bowman–Birk soybean trypsin inhibitors (KTI and BBTI) were measured before and after ultrasound treatments. The differences between KTI and BBTI in conformation changes and resistance to ultrasound were observed. The secondary structures of KTI were found to be composed of β-sheet (22.5%), β-turn (16.2%) and random coils (61.4%) while that of BBTI composed of only β-sheet (52.6%) and random coils (47.4%). KTI lost its inhibitory activity more quickly than BBTI, proportionally to the ultrasound amplitudes and sonication durations used. Relevant synchronous phenomena observed included the inactivation of KTI, significant rise in sulfhydryl content and corresponding conformation changes, in which there were dramatic decreases in both β-turn and random coil contents and increase in the β-sheet structure over the entire sonication duration and ultrasonic amplitude scale used by the study. Ultrasound affected the activities and conformations of KTI and BBTI by exerting an influence on their disulfide bonds. For KTI, up to 55% of inhibitory activity could be inactivated, at which about 71.5% of disulfide bonds were altered and the [θ]_200nm value was changed from native −2545 deg cm² dmol⁻¹ to −1827 deg cm² dmol⁻¹. Whereas for BBTI, far-UV CD spectra, β-sheet and random structures were barely affected, only about 5.29% of disulfide bonds were found altered and the [θ]_200nm value was changed only from native −797 deg cm² dmol⁻¹ to −700 deg cm² dmol⁻¹. It is concluded that ultrasound inactivates KTI by inducing a reduction in the disulfide bonds and then changes the conformations.     

Direct enrichment of olive oil in oleuropein by ultrasound-assisted maceration at laboratory and pilot plant scale

The possibility to improve the nutritional value of olive oil by enriching it in phenolic compounds from olive leaves (e.g., oleuropein) by ultrasonic maceration was studied. The experimental design used led to the following optimal extraction conditions: ultrasonic power of 60 W, temperature of 16 °C and sonication duration of 45 min. The high total phenolic content (414.3 ± 3.2 mg of oleuropein equivalent/kg of oil), oleuropein (111.0 ± 2.2 mg/kg of oil) and α-tocopherol (55.0 ± 2.1 g/kg of oil) concentrations obtained by optimized ultrasound-assisted extraction (UAE) proved the efficiency of this process when compared with the conventional solid-liquid extraction. Histochemical analyses showed that this efficiency is due to specific alteration of the phenol-containing leaf structures. Furthermore, the radical-scavenging activity of the processed oil (DPPH test) and its stability toward lipid autoxidation (heating test) confirmed its enrichment in antioxidants. Sensory evaluation of the enriched olive oil showed a slight increase in bitterness but an overall acceptability. Finally, the enriched olive oil was characterized by clear green color (L^∗, a^∗, b^∗ parameters).     

Sonolytic degradation of hazardous organic compounds in aqueous solution

Benzene, chlorobenzene, 1,2-, 1,3-, 1,4-dichlorobenzene, biphenyl, and polychlorinated biphenyls such as 2-, 4-chlorobiphenyl and 2,2′-dichlorobiphenyl in aqueous solutions have been subjected to sonolysis with 200 kHz ultrasound at an intensity of 6 W cm⁻² under an argon atmosphere. 80–90% of initial amount of these compounds were degraded by 30–60 min of sonication when the initial concentrations were 10–100 μmol l⁻¹. The degradation rate of these compounds increased with increase in their vapor pressures. In all cases of sonolysis of chlorinated organic compounds, an appreciable amount of liberated chloride ion was observed.     

Magnetic properties of Sm–Co–B-based nanocomposite magnets

The magnetic properties of nanocomposite melt-spun magnets with composition Sm_16−xCo_68+xB₁₆ (x=0–10, 2 at% interval) and Sm₈Co_92−yB_y (y=10–18, 2 at% interval) have been studied systematically. Several ribbons were fabricated with a wheel speed of 50 m/s, followed by annealing in the temperature range of 700–800°C for 2.5–40 min. XRD results and magnetization versus temperature curves showed that almost all of the samples were composed of the tetragonal Sm₂Co₁₄B and rhombohedral SmCo₁₂B₆ phases which are not magnetically hard at room temperature. However, a relatively high coercivity in the range of 3.5–5.5 kOe has been obtained in these samples. The highest coercivity of 5.5 kOe and a very promising β value of −0.28%/°C were obtained in Sm₈Co₇₄B₁₈ ribbons annealed at 750°C for 5 min. The high coercivities are attributed to the small grain size of the 2 : 14 : 1 phase, in which the large surface areas enhance its effective anisotropy, and make it uniaxial type.     

Sonochemical removal of trihalomethanes from aqueous solutions

In this research, ultrasound irradiation was employed to degrade the trihalomethanes, THMs: CHCl₃, CHBrCl₂, CHBr₂Cl, CHBr₃, and CHI₃. The kinetics reaction rates and removal efficiencies of the THMs compounds, as a sole component in the aqueous solutions, were studied. Batch experiments were conducted at an ultrasonic frequency of 20 kHz and acoustic intensity of 3.75 W/cm². The first-order degradation rate constants and the sonolysis efficiencies followed the decreasing order of CHCl₃ > CHBrCl₂ > CHBr₂Cl > CHBr₃ > CHI₃. Up to 100% of the CHCl₃ was removed, while only 60% of the CHI₃ was sonodegraded, after 180 min sonication. The THMs vapor pressure was found to be the most important parameter affecting the sonodegradation kinetics and efficiency, while the bond dissociation energy and hydrophilic/hydrophobic characteristics of the THMs compounds were found to be of secondary importance.     

Engineering design and prototype development of a full scale ultrasound system for virgin olive oil by means of numerical and experimental analysis

The aim of the virgin olive oil extraction process is mainly to obtain the best quality oil from fruits, by only applying mechanical actions while guaranteeing the highest overall efficiency. Currently, the mechanical methods used to extract virgin oils from olives are basically of two types: the discontinuous system (obsolete) and the continuous one. Anyway the system defined as “continuous” is composed of several steps which are not all completely continuous, due to the presence of the malaxer, a device that works in batch. The aim of the paper was to design, realize and test the first full scale sono-exchanger for the virgin olive oil industry, to be placed immediately after the crusher and before the malaxer. The innovative device is mainly composed of a triple concentric pipe heat exchanger combined with three ultrasound probes. This mechanical solution allows both the cell walls (which release the oil droplets) along with the minor compounds to be destroyed more effectively and the heat exchange between the olive paste and the process water to be accelerated. This strategy represents the first step towards the transformation of the malaxing step from a batch operation into a real continuous process, thus improving the working capacity of the industrial plants. Considering the heterogeneity of the olive paste, which is composed of different tissues, the design of the sono-exchanger required a thorough fluid dynamic analysis. The thermal effects of the sono-exchanger were monitored by measuring the temperature of the product at the inlet and the outlet of the device; in addition, the measurement of the pigments concentration in the product allowed monitoring the mechanical effects of the sono-exchanger. The effects of the innovative process were also evaluated in terms of extra virgin olive oil yields and quality, evaluating the main legal parameters, the polyphenol and tocopherol content. Moreover, the activity of the polyphenol oxidase enzyme in the olive paste was measured.     

The IR spectra of Mg5C(CO) complexes on the (0 0 1) surfaces of polycrystalline and single crystal MgO

The FTIR spectroscopy of carbon monoxide adsorbed on polycrystalline MgO smoke has been investigated as a function of the CO equilibrium pressure at constant temperature (60 K) (optical isotherm) and of the temperature (in the 300–60 K range) at constant CO pressure (optical isobar). In both cases the spectra fully reproduce those of CO adsorbed on the (0 0 1) surface of UHV cleaved single crystals [Heidberg et al., Surf. Sci. 331–333 (1995) 1467]. This result, never attained in previous investigations on dispersed MgO, contribute to bridging the gap which is commonly supposed to exist between surface science and the study of “real” (defective) systems. Depending on the surface coverage θ the main spectral features due to the CO/MgO smoke interaction are a single band shifting from 2157.5 (at θ→0) to 2150.2 cm⁻¹ (at θ=1/4) or a triplet, at 2151.5, 2137.2 and 2132.4 cm⁻¹ (at θ>1/4). These manifestations are due to the ν(CO) modes of Mg_5C²⁺· · · CO adducts formed on the (0 0 1) terminations of the cubic MgO smoke microcrystals. The formation of the CO monolayer is occurring in two different phases: (i) a first phase with CO oscillators perpendicularly oriented to the surface (2157–2150 cm⁻¹) and (ii) a second phase constituted by an array of coexisting perpendicular and tilted species (triplet at 2151.5, 2137.2 and 2132.4 cm⁻¹). A much weaker feature at 2167.5–2164 cm⁻¹ is assigned to Mg_4C²⁺· · · CO adducts at the edges of the microcrystals. The heat of adsorption of the perpendicular Mg_5C²⁺· · · CO complex in the first phase has been estimated from the optical isobar and results to be 11 kJ mol⁻¹.     

Preparation of tantalum oxide thin films by photo-assisted atomic layer deposition

Tantalum oxide thin films were prepared by photo-assisted atomic layer deposition (Photo-ALD) in the substrate temperature range of 170–400 °C using Ta(OC₂H₅)₅ and H₂O as precursors. The constant growth rates of 0.42 and 0.47 Å per cycle were achieved for the films grown by normal ALD and Photo-ALD, respectively. The increased growth rate in Photo-ALD is probably due to the reactive surface by photon energy and faster surface reaction. In Photo-ALD, however, the constant growth rate started at lower temperature of 30 °C and one cycle time shortened up to 5.7 s than that of normal ALD. The films grown by normal ALD and Photo-ALD were amorphous and very smooth (0.21–0.35 nm) as examined by X-ray diffractometer and atomic force microscopy, respectively. Also, the refractive index was found to be 2.12–2.16 at the substrate temperature of 190–300 °C, similar to that of the film grown by normal ALD. However, the remarkably low leakage current density of 0.6×10⁻⁶ A/cm² to 1×10⁻⁶ A/cm² at applied field of 1 MV/cm is several order of magnitude smaller than that of normal ALD, probably due to the presence of reactive atom species.     

Trajectory-property relationships in MOD-derived YBCO films

A study of the physical and chemical changes during processing in MOD-derived YBCO films was performed. Fully processed films were 70–85% of theoretical density. The sintering rate increased substantially in the compositional range F/Ba = 1.8–1.5. The activation energy for sintering decreased above a P(H₂O) dependent threshold temperature. XRD indicated this temperature/composition threshold also corresponded to YBCO nucleation, suggesting ex situ YBCO forms in contact with a melt. The ramp rate and P(H₂O) were used to control F/Ba trajectories, which were correlated to performance. The nucleation of YBCO was strongly dependent on processing conditions. Nucleation temperature was varied by at least 60 °C in the study. The optimal YBCO nucleation temperature in the 300–800 nm films was around 725 °C. a-axis grains dominated the microstructures of films where YBCO nucleated at <700 °C. Large second phases, but no a-axis grains, were found when the nucleation temperature was >750 °C.     

Application of ultrasound as pretreatment for extraction of podophyllotoxin from rhizomes of Podophyllum peltatum

The effect of high-power ultrasound pretreatment on the extraction of podophyllotoxin from Podophyllum peltatum was investigated. Direct sonication by an ultrasound probe horn was applied at 24 kHz and a number of factors were investigated: particle size (0.18-0.6 mm), type of solvent (0-100% aqueous ethanol), ultrasonic treatment time (2-40 min), and power of ultrasound (0-100% power intensity, maximum power: 78 W). The optimal condition of ultrasound was achieved with 0.425-0.6 mm particle size, 10 min sonication time, 35 W ultrasound power, and water as the medium. There was no obvious degradation of podophyllotoxin with ultrasound under the applied conditions, and an improvement in extractability was observed. The SEM microscopic structure change of treated samples disclosed the effect of ultrasound on the tissue cells. The increased pore volume and surface area after ultrasonic treatment also confirmed the positive effect of ultrasound pretreatment on the extraction yield of podophyllotoxin from the plant cells.     

Effect of exposure parameters on cavitation induced by low-level dual-frequency ultrasound

In order to quantify the effects of exposure parameters under therapeutic conditions such as sonodynamic therapy, it is necessary initially to evaluate the inertial cavitation activity in vitro. In this study, the dependence of cavitation activity induced by the low-level dual-frequency ultrasound irradiation on exposure parameters has been studied. Experiments were performed in the near 150 kHz and 1 MHz fields in the progressive wave mode. It has been shown that at constant ultrasound energy the fluorescence intensity for continuous sonication is higher than for pulsed mode. With increasing the duty cycle of pulsed field, the inertial cavitation activity is increased. The activity of cavitation produced by simultaneous combined sonication by two ultrasound fields is remarkably higher than the algebraic sum of effects produced by fields separately (p-value < 0.05). This study shows that simultaneous combined dual-frequency ultrasound sonication in continuous mode is more effective in producing inertial cavitation activity at low-level intensity. Therefore, it is concluded that investigations in this combined ultrasound sonication can be useful in sonodynamic therapy for superficial tumors.     

Picosecond nonlinear optical response of Ba0.5Sr0.5TiO3 thin films fabricated by pulsed laser deposition

Well-crystallized Ba_0.5Sr_0.5TiO₃ thin films with good surface morphology were prepared on MgO(1 0 0) substrates by pulsed laser deposition technique at a deposition temperature of 800 °C under the oxygen pressure of 2 × 10⁻³ Pa. X-ray diffraction and atomic force microscopy were used to characterize the films. The full width at half maximum of the (0 0 2) Ba_0.5Sr_0.5TiO₃ rocking curve and the root-mean-square surface roughness within the 5 μm × 5 μm area were 0.542° and 0.555 nm, respectively. The nonlinear optical properties of the films were determined by a single beam Z-scan method at a wavelength of 532 nm with laser duration of 55 ps. The results show that Ba_0.5Sr_0.5TiO₃ thin films exhibit a fast third-order nonlinear optical response with the nonlinear refractive index and nonlinear absorption coefficient being n₂ = 5.04 × 10⁻⁶ cm²/kW and β = 3.59 × 10⁻⁶ (m/W), respectively.     

Electrode contact study for SiGe thin film operated at high temperature

A study on the electrode contact of the sputtered SiGe thin film is reported for application of devices working at high temperature. Surface morphological characterization with optical microscope and AFM (atomic force microscope) together with the electrical characterization by TLM measurements (transmission line method) were performed before and after aging at 500 °C for 24 h using various sputtered multilayer electrodes, Ti/Au/Ti, Ta/Pt/Ta and Ti/Pt/Ti, on 300-nm B-doped SiGe thin film deposited by magnetron sputtering and furnace crystallisation at high temperature. After aging at 500 °C for 24 h, the Ti/Au/Ti multilayer electrodes seriously degraded to be non-ohmic contact, showing rough surface morphology. The Ti/Pt/Ti metal layers showed the lowest specific contact, resistivity before and after aging, 1.46 × 10⁻³ Ω cm² and 1.68 × 10² Ω cm² respectively.     

Characterization of high-k gate dielectric/silicon interfaces

We have shown that, for thermally evaporated Ta₂O₅ or ZrO₂ thin films on Si(1 0 0), O₂ annealing at 300–500 °C causes the formation of an interfacial silicon oxide layer as thin as 1–2 nm which can be interpreted in terms of their high permeability to oxygen. And we have demonstrated how useful the energy loss spectra of photoexcited electrons from core levels such as O 1s are to measure the energy bandgaps of very thin insulators. With the combination of measured bandgaps and valence band lineups determined for X-ray photoelectron spectroscopy valence band spectra, we have determined the energy band alignments of Ta₂O₅ and ZrO₂ with Si(1 0 0) before and after the O₂ annealing at 500 °C. In addition, we have demonstrated that total photoelectron yield spectroscopy provides us direct information to quantify the energy distributions of both the defect states in the high-k dielectrics and the dielectric/Si(1 0 0) interface states over nearly entire Si bandgap.     

X-ray photoelectron spectroscopy investigation of the carburization of 310 stainless steel

The surface of 310 stainless steel (310SS) samples was investigated by X-ray photoelectron spectroscopy (XPS) after 500 h cyclic exposure to two carburizing atmospheres: CH₄ (2%)–H₂ (98%) at 800 °C, and CH₄ (10%)–H₂ (90%) at 1100 °C. The depth distribution of various elements in the surface region was obtained by XPS after successive cycles of argon etching. The microstructure of the alloy was observed by scanning electron microscopy (SEM) and the phases formed during the exposure were analyzed by X-ray diffraction (XRD). The results showed that the major phases that were formed within few micrometer depth during exposure at 800 °C include both iron and chromium carbides. (Mn, Cr) oxide was also formed as a result of the reaction with the residual oxygen of the atmosphere. A region of few microns width that was relatively depleted of chromium was formed under the surface as a result of the outwards diffusion of chromium. The exposure to the reducing atmosphere at 1100 °C led to the formation of various iron and chromium carbides. No oxide was formed during exposure. In all exposed samples, the surface was Cr enriched while nickel remained buried under the surface region that reacted with the atmosphere.     

The effect of thickness and annealing condition on the microstructure and magnetic properties of Fe/Pt multilayer thin films

[Fe(0.5 nm)/Pt(0.5 nm)]₄₀, [Fe(1 nm)/Pt(1.5 nm)]₂₀ and [Fe(3 nm)/Pt(3 nm)]₁₀ multilayer were prepared by DC magnetron sputtering. By conventional furnace annealing (CA) at 270–600 °C for various time, all of the films still remained the disordered structure with the soft magnetic phase. By rapid thermal annealing (RTA) at 500 °C for various time, we obtained the [Fe(1 nm)/Pt(1.5 nm)]₂₀ and [Fe(3 nm)/Pt(3 nm)]₁₀ films with L1₂ ordered FePt₃ phase which was almost ferromagnetic at room temperature. However, the [Fe(0.5 nm)/Pt(0.5 nm)]₄₀ films was still disordered state even under RTA. Compared with CA, RTA exposed an outstanding effect on accelerating the phase transition when the film thickness is over [Fe(0.5 nm)/Pt(0.5 nm)]₄₀.