Effects Of Ultrasound Parameters Research Articles

Interaction mechanisms of peanut protein isolate and high methoxyl pectin with ultrasound treatment: The effect of ultrasound parameters, biopolymer ratio, and pH.

Ultrasound could effectively change molecular structure of proteins, polysaccharides, and their interactions, and was used to treat the peanut protein isolate-high methoxy pectin (PPI-HMP) complexes in this study. Effects of different ultrasound parameters, PPI-HMP mixing ratio (40:1-5:2), and pH (2.0-8.0) on the PPI-HMP interactions were investigated. Turbidity, solution appearance, and Zeta-potential analysis revealed an electrostatic interaction between PPI and HMP from pH 2.0 to pH 6.0. Ultrasound changed the tertiary structure conformation of PPI according to the surface hydrophobicity analysis. Increased ultrasound power density and pH broke the hydrogen bonds between the complexes according to Fourier transform infrared spectroscopy analysis. Apparent viscosity and confocal laser scanning microscopy analysis showed that appropriate ultrasound treatment (5.43W/cm3, 25min, 25°C) reduced the viscosity of the complexes, and enhanced the electrostatic and hydrophobic interactions between PPI and HMP. These findings will contribute to the application of PPI-HMP complexes in the food industry.

Process intensification of acidolysis reaction catalysed by enzymes for synthesis of designer lipids using sonication

Designer lipids find a wide range of applications in food, pharmaceuticals and nutraceutical industries. The current work focuses on intensified production of designer lipids using ultrasound assisted enzymatic acidolysis reaction between long chain triglycerides from Linseed oil (LO) and MCFAs i.e. octanoic acid or decanoic acid. The synthesised designer lipids contain sn-1,3 position on glycerol backbone occupied by MCFAs and sn-2 position occupied by PUFAs, thus having the potential of numerous applications in food and pharma sector. Studies into effect of ultrasound parameters and reaction conditions on the yield demonstrated that the optimum operating conditions as molar ratio of LO: MCFAs of 1:5, temperature of 40 °C and Novozyme 435 dosage of 5% (based on substrate weight) as well as ultrasound conditions of 50% duty cycle and 90 min of irradiation time resulted in maximum yield as 96%. Comparison of ultrasound assisted synthesis with the conventional synthesis (less than 20% yield in 90 min and requirement of 26 h to reach equilibrium yield of 82.6%) demonstrated the intensification benefits as higher yield and lower reaction time for the ultrasound assisted approach. It was also elucidated that Novozyme 435 was effectively recycled for 12 cycles without much effect on the yield. Overall the work clearly demonstrated the efficacy of the ultrasound intensified approach for synthesis of designer lipids, also elucidating key design information for the optimum operating conditions.

Streaming-enhanced, chip-based biosensor with acoustically active, biomarker-functionalized micropillars: A case study of thrombin detection

Enzyme-linked immunosorbent assay is a widely used analytical technique for detecting and quantifying disease-specific protein biomarkers. Despite recent progresses in disease-specific protein biomarkers detection with microfluidic chips, many devices still suffer from the limited mass transport of target molecules, and consequently low detection efficiency or long incubation time. In this work, we present a novel strategy to significantly enhance the sensing efficiency of a chip-based biosensor by exploiting micro-streaming in an acoustofluidic device, which boosts intermolecular interactions and a hybridization chain reaction to increase the fluorescent signals. This device was made of a microfluidic chip that contains an array of PDMS micropillars in a ship-shaped microchannel. And the inner surface of the channel was functionalized with capture aptamers that bind with thrombin, chosen as a model target molecule. An ultrasonic transducer underneath the chip operating at 150 kHz generates circular micro-streaming flows around the pillars that significantly improves the binding efficiency of thrombin with capture aptamers by 1) increasing the retention time and 2) enhancing mass transport via local convection versus diffusion. The effects of ultrasound parameters, such as operating frequencies and voltages, on the distribution and magnitude of flows were optimized to obtain a better performance of the sensor chip. Under the optimized conditions, the detection limit was increased by one order of magnitude. Although this work has focused on the detection of thrombin as a model molecule, this streaming-enhanced, microstructure-based sensing strategy can be applied to detect a wide range of molecules or even cells.

Effects of power ultrasound on the activity and structure of β-D-glucosidase with potentially aroma-enhancing capability.

β‐d‐glucosidase can release aroma precursors to improve the flavor of plant food, but the hydrolysis efficiency of the enzyme is low; the purpose of this study was to improve the enzyme activity using ultrasound. The effects of ultrasound parameters on β‐d‐glucosidase activity were investigated, and the respective structures of enzyme activated and enzyme inhibited were further analyzed. Low temperature (20–45°C), low ultrasonic intensity (<181.53 W/cm2), and short treatment time (<15 min) led to the activation of β‐d‐glucosidase, whereas high temperature (45–60°C), high ultrasonic intensity (>181.53 W/cm2), and long treatment time (>15 min) led to its inhibition. Application of ultrasound lowered the optimum temperature for β‐d‐glucosidase activity from 50 to 40°C. Ultrasound did not change the primary structures of the enzyme, but changed the secondary structures. When ultrasound activated β‐d‐glucosidase, the α‐helix contents were increased, the β‐fold and irregular coil content were reduced. When ultrasound inhibited β‐d‐glucosidase, the contents of β‐folds were increased, the α‐helix and irregular coil contents were reduced.. In summary, activation or inhibition of β‐d‐glucosidase under ultrasound was determined by the ultrasound conditions. This study suggests that ultrasound combined with β‐D‐glucosidase can be used in aroma‐enhancing.

Optimization of Triton X-100 removal and ultrasound probe parameters in the preparation of multiwalled carbon nanotube buckypaper

A highly porous film composed of a three-dimensional network of multi-walled carbon nanotube (MWCNT), also known as buckypaper (BP), was prepared by vacuum filtration of a well-dispersed suspension of MWCNT/H20 with the aid Triton X-100 surfactant. The key contribution of this work is to achieve the best parameters during the preparation of the suspension and find the best way to remove the excess triton X-100 from the nanotube network. The stability of suspension in different pH, the adsorption capacity, and the reusability of MWCNT was also evaluated. The effects of ultrasound parameters on the BP properties were systematically investigated and characterized by Raman Spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and electric resistivity using a four-point probe technique. In addition, the results of using different solvents to wash the BP after filtration process were analyzed by Thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FT-IR), and Field emission gun scanning electron microscopy (FEG-SEM). The optimum condition employed in this work (25 min–40%) exhibited the ID/IG ratio of 2.17 and L002 of 5.597 nm, which suggests less damage to MWCNT. This study confirms that MWCNT-BP can be used to fabricate high-loading CNT/polymer composites with improved electrical properties.

The effects of ultrasound parameters and microbubble concentration on acoustic particle palpation.

The elasticity of tissue-an indicator of disease progression-can be imaged by ultrasound elasticity imaging technologies. An acoustic particle palpation (APP) has recently been developed-the use of ultrasonically driven acoustic particles (e.g., microbubbles)-as an alternative method of tissue deformation. APP has the potential to improve the resolution, contrast, and depth of ultrasound elasticity imaging; but the tissue displacement dynamics and its dependence on acoustic pressure, center frequency, and microbubble concentration remains unknown. Here, displacements of at least 1 μm were produced by applying ultrasound onto a microbubble solution (concentration: 10 × 106 microbubbles ml-1) placed within a tunnel surrounded by a 5% gelatin phantom. Displacements of more than 10 μm were produced using a 1, 3.5, or 5 MHz center frequency pulse with peak-rarefactional pressures of 470, 785, and 1210 kPa, respectively. The deformation of the distal wall varied spatially and temporally according to the different parameters investigated. At low pressures, the deformation increased over several milliseconds until it was held at a nearly constant value. At high pressures, a large deformation occurred within a millisecond followed by a sharp decrease and long stabilization. Ultrasound exposure in the presence of microbubbles produced tissue deformation (p < 0.05) while without microbubbles, no deformation was observed.

Acoustic intensity in ultrasound field and ultrasound-assisted gelling of surimi

The effects of ultrasound parameters, and of the container materials used for surimi, on acoustic intensity were investigated. The frequency of ultrasound significantly affected the acoustic intensity. However, the relationship between the acoustic intensity and the frequency of the ultrasound device was not linear. The acoustic intensity increased as the height of the media increased. In addition, the acoustic intensity increased initially, but then decreased, as the volume of the media increased. Two container materials were tested: polyvinyl chloride (PVC) film and an aluminum box. The acoustic intensity was decreased significantly by the use of either material. The barrier effect of the aluminum box was weaker than that of the PVC film at lower frequencies, whereas the barrier effect of the PVC film was weaker than that of the aluminum box at higher frequencies. The gel strength of surimi increased with as the acoustic intensity increased when the latter was above a certain level. Changes in the secondary structure of myofibrillar protein were found to cause the increase in the gel strength.

Experimental Design and Optimization of Ultrasound Treatment:Functional and Physical Properties of Sonicated Ice Cream Model Mixtures

The aim of this study was to determine the effect of high power ultrasound on functional properties of ice-cream model mixtures. Mixture composed of sucrose, glucose, whole milk powder, whey protein concentrates (WPC) and distilled water was ultrasonically treated according to different parameters. Amplitude of ultrasounds, percentage of WPC in the sample and time of treatment are the three variables considered. Effect of ultrasound parameters on rheological properties (measurement of coefficient of consistency), thermal properties (measurement of initial freezing point) and foaming properties (measurement of maximal foam capacity) was observed. Experiment was designed using model called Central Composite Design (CCD) permitting to consider the significant factors for each property, and results were analyzed and process was optimized through response surface methodology-RSM. Through study, optimal conditions of ultrasound treatment (amplitude, treatment time and percentage of WPC) by which experiment should be performed were obtained. The factor “percentage of WPC” is significant from a rheological and thermal point of view. Regarding foaming properties, the significant factor that is to say affecting most the value of the maximum foam capacity is the duration of ultrasound treatment.