Effect of ultrasound treatment on microstructure,colour and carotenoid content in fresh and dried carrot tissue

The aim of the study was to investigate the influence of ultrasound treatment on the carrot tissue microstructure, colour and carotenoids content. To avoid adverse effects of rinsing out substances contained in the raw material, carrot slices were vacuum-packed and treated with ultrasounds in an ultrasonic bath using 21 and 35 kHz frequency for 10, 20 and 30 min. Images of the carrot tissue made by scanning electron microscope were analysed by calculating the cross-section area for each cell. The colour was measured using CIE L^∗a^∗b^∗ method. To determine total carotenoid content spectrophotometric method was used. Obtained results indicate that the structural properties of carrots treated with ultrasound were significantly different from the samples without any treatment and it was clearly noticed during analysing images of scanning electron microscope. There was observed the influence of ultrasound treatment on colour L^∗, a^∗ and b^∗ parameters, especially for carrot treated with ultrasound for 30 min, independent of the applied frequency of the ultrasonic waves. Similarly, sonic treatment resulted in substantial increase of carotenoid in comparison to raw carrot, especially in the case of 35 kHz frequency ultrasounds. Probably, such significant increase is caused by the destruction of the original structure and thus higher extraction ability of these compounds.     

Measurement of microstructural changes promoted by ultrasound application on plant materials with different porosity

This research investigated the effects of ultrasound application (192 ± 6 W/L) on the microstructure of vegetables/fruits with different porosities, cell sizes and patterns (eggplants, beetroots, and apples), submitted to an immersion treatment in different liquids: distilled water, citric acid (1% w/v), and the vegetable/fruit juice, at 25 °C during 5 min. The ultrasound application did not significantly (p > 0.05) affect the size of the cells of the most porous material (eggplant) compared to the samples immersed without ultrasound assistance. The apple samples (with a middle-high porosity and the largest cells) were the most affected by ultrasound application. The median cell areas of samples treated with ultrasound in water and apple juice were 26 and 20% larger than those of samples treated without ultrasound, mainly because of cell wall disruption which caused the cells to merge into bigger clusters, but no effect was observed with the citric acid. Ultrasound application significantly (p < 0.05) increased the median cell area of the less porous raw matter (beetroot) only when the treatment was carried out in the vegetable juice (cells were 26% larger after treatment assisted with ultrasound than without it). Thus, the effects of ultrasound differ in materials with initially different characteristics.     

超声波对菠萝果蛋白酶活性和光谱的影响

以菠萝果为材料，用盐析法制备菠萝果蛋白酶粗酶，进一步经SephadexG-50和DEAE-纤维素柱层析纯化，其SDS—PAGE呈单一的电泳带，并获得了菠萝果蛋白酶结晶。一定参数的超声作用可以使酶活力提高，经光谱分析，超声处理后酶的吸收光谱不改变，而荧光发射峰由336nm红移到339nm，紫外差示光谱在一定的波长也呈现出明显的正峰和负峰。本文讨论了超声波影响菠萝果蛋白酶活性的机理。     

Effect of ultrasound on protein functionality

The review focus on the effect of ultrasound on protein functionality. The presence of transient ultrasonic mechanical waves induce various sonochemical and sonomechanical effects on a protein. Sonochemical effects include the breakage of chains and/or the modification of side groups of aminoacids. Sonomechanical modifications by enhanced molecular agitation, might lead to the transient or permanent modification of the 3D structure of the folded protein. Since the biological function of proteins depends on the maintenance of its 3D folded structure, both sonochemical and sonomechanical effects might affect its properties. A protein might maintain its 3D structure and functionality after minor sonochemical effects, however, the enhanced mass transfer by sonomechanical effects might expose internal hydrophobic residues of the protein, making protein unfolding to an irreversible denatured state. Ultrasound enhanced mass transport effects are unique pathways to change the 3D folded structure of proteins which lead to a new functionality of proteins as support shield materials during the formation microspheres. Enzymes are proteins and their reactions should be conducted in a reactor set-up where enzymes are protected from sonic waves to maximize their catalytic efficiency. In this review, focused examples on protein dispersions/emulsions and enzyme catalysis are given.     

超声波对固定化酶活性的影响

本文介绍了超声波对固定化酶的影响，同时对作用过程中的影响因素进行了阐述，并探讨了超声波影响固定化酶的可能机理。     

Effect of ultrasound on the immunogenic corn cob xylan

Changes in the structural, molecular and functional properties of the immunogenic corn cob xylan evoked by ultrasonication in water, 1% NaOH and 5% NaOH were investigated. The reduction of the high molar mass (MM) fraction was more intense than that of the medium MM fraction, depending on the sonic power, sonication time, and alkali concentration. The chain degradation was more effective in the alkaline media. The UV-absorbing component, accompanying the xylan polymers in the whole MM range, showed an accumulation in the high MM region as well as shiftening to higher sizes, particularly in 5% NaOH. The sugar composition and primary structure of the xylan was almost retained under all irradiation conditions studied. Although the biological activity of the xylan was affected by the ultrasound, no significant decrease of the biological response was found at short irradiation time and low sonic power.     

Effect of ultrasound-assisted freezing on the physico-chemical properties and volatile compounds of red radish

Power ultrasound, which can enhance nucleation rate and crystal growth rate, can also affect the physico-chemical properties of immersion frozen products. In this study, the influence of slow freezing (SF), immersion freezing (IF) and ultrasound-assisted freezing (UAF) on physico-chemical properties and volatile compounds of red radish was investigated. Results showed that ultrasound application significantly improved the freezing rate; the freezing time of ultrasound application at 0.26 W/cm² was shorten by 14% and 90%, compared to IF and SF, respectively. UAF products showed significant (p < 0.05) reduction in drip loss and phytonutrients (anthocyanins, vitamin C and phenolics) loss. Compared to SF products, IF and UAF products showed better textural preservation and higher calcium content. The radish tissues exhibited better cellular structures under ultrasonic power intensities of 0.17 and 0.26 W/cm² with less cell separation and disruption. Volatile compound data revealed that radish aromatic profile was also affected in the freezing process.     

Effect of ultrasound on the kinetics of anti-solvent crystallization of sucrose

The effect of ultrasound on the kinetics of anti-solvent crystallization of sucrose was studied. The influence of temperature, stirring rate, supersaturation and ultrasonic power on the anti-solvent crystallization of sucrose was investigated. The relationship between infrared spectral characteristic band of sucrose and supersaturation was determined with an online reaction analyzer. The crystal size distribution of sucrose was detected by a laser particle-size analyzer. Ultrasound accelerated the crystallization process, and had no impact on the crystal shape. Abegg, Stevens and Larson model was fitted to the experimental data, and the results were the following: At 298.15 K, the average size of crystals was 133.8 μm and nucleation rate was 4.87 × 10⁹ m⁻³·s⁻¹ without ultrasound. In an ultrasonic field, the average size was 80.5 μm, and nucleation rate was 1.18 × 10¹¹ m⁻³·s⁻¹. Ultrasound significantly reduced the average size of crystals and improved the nucleation rate. It was observed that the crystal size decreased with the increase of stirring rate in silent environment. When the stirring rate increased from 250 to 400 rpm, the average size decreased from 173.0 to 132.9 μm. However, the stirring rate had no significant impact on the crystal size in the ultrasonic field. In addition, the activation energy of anti-solvent crystallization of sucrose was decreased, and the kinetic constant of nucleation rate was increased due to the effect of ultrasound. In the ultrasonic field, the activation energy was reduced from 20422.5 to 790.5 J·mol⁻¹, and the kinetic constant was increased from 9.76 × 10² to 8.38 × 10⁸.     

Effect of reaction temperature on the size and morphology of scorodite synthesized using ultrasound irradiation

Synthesis of scorodite (FeAsO₄·2H₂O) using dynamic action agglomeration and the oxidation effect from ultrasound irradiation was investigated. The effect of different reaction temperatures (90, 70, 50, and 30 °C) on the size and morphology of scorodite particles synthesized under O₂ gas flow and ultrasound irradiation was explored because the generation of fine bubbles depends on the solution temperature. At 90 °C, the size of scorodite particles was non-homogeneous (from fine particles (<1 μm) to large particles (>10 μm)). The oxidation–reduction potential (ORP) and yield at 90 °C showed lower values than those at 70 °C. The scorodite particles, including fine and non-homogeneous particles, were generated by a decrease in the oxidation of Fe(II) to Fe(III) and promotion of dissolution caused by the generation of radicals and jet flow from ultrasound irradiation. Using ultrasound irradiation in the synthesis of scorodite at low temperature (30 °C) resulted in the appearance of scorodite peaks in the X-ray diffraction (XRD) pattern after a reaction time of 3 h. The peaks became more intense with a reaction temperature of 50 °C and crystalline scorodite was obtained. Therefore, ultrasound irradiation can enable the synthesis of scorodite at 30 °C as well as the synthesis of large particles (>10 μm) at higher temperature. Oxide radicals and jet flow generated by ultrasound irradiation contributed significantly to the synthesis and crystal growth of scorodite.     

Effect of ultrasound on the kinetics of cation exchange in NaX zeolite

In this study, we focused on the effect of ultrasound on ion exchange kinetics to obtain the Li-, Ca- and Ce-rich NaX zeolite. The results were compared to those obtained from the traditional batch exchange method under similar conditions. Contact time and initial cation concentration (fold equivalent excess) were studied. Ultrasound enhanced the replacement of Na⁺ ion with Li⁺, Ca²⁺ and Ce³⁺ ions in the extra-framework of zeolite up to 76%, 72% and 66%, respectively. The intraparticle diffusion is the rate limiting step in the ion exchange for both exchange methods. As compared to the traditional exchange method, the ultrasonic method applied in this study was found to be very effective on the exchange amount at equilibrium.     

Effect of intensifying additives on the degradation of thiamethoxam using ultrasound cavitation

The present study has investigated the degradation of thiamethoxam using ultrasound cavitation (US) operated at a frequency of 20 kHz and its combination with intensifying additives viz. hydrogen peroxide, Fenton and photo-Fenton reagent. At the outset, the performance of US (20 kHz) has been maximised by the optimization of process parameters. Highest rate of degradation of thiamethoxam was observed at the optimum ultrasonic power density of 0.22 W/mL, thiamethoxam concentration of 10 ppm and the pH of 2. The established optimum values of operating parameters were used further in case of combined treatment approaches. The effect of concentration of H₂O₂ on the rate of degradation of thiamethoxam in the case of US + H₂O₂ process has confirmed the existence of optimum concentration of H₂O₂ with the ratio of thiamethoxam: H₂O₂ as 1:10. US + Fenton process indicated the optimal molar ratio of FeSO₄·7H₂O:H₂O₂ as 1:15. The combined processes of US + H₂O_2, US + Fenton and US + photo-Fenton have resulted in the extent of degradation of 20.47 ± 0.61%, 34.41 ± 1.03% and 85.17 ± 2.56% respectively after 45 min. of operation. These combined processes lead to the synergistic index of 2.04 ± 0.06, 2.26 ± 0.07 and 2.42 ± 0.07 in case of US + H₂O₂, US + Fenton and US + photo-Fenton processes respectively over only US/stirring treatment with the additive. Additionally, the extent of mineralization and the energy efficiency of individual and combined processes have been compared. US + photo-Fenton process has been found to be the best strategy for effective degradation of thiamethoxam with a significant intensification benefit. The by-products formed during the ultrasonic degradation of thiamethoxam have been identified by using LC-MS/MS analysis.     

Effect of ultrasonic far-infrared synergistic drying on the characteristics and qualities of wolfberry (Lycium barbarum L.)

This study investigated the effects of ultrasonic frequency, ultrasonic power, irradiation height and temperature on the drying characteristics, quality and microstructure of wolfberry by ultrasonic-assisted far-infrared drying. By fitting five commonly used thin-layer drying mathematical models, it was found that the coefficient of determination (R²) of the Weibull model was 0.99400–0.99825, the root mean square error (RMSE) was 1.2162 × 10^-4–4.5209 × 10^-4, and the reduced chi-square (χ²) was 0.00207–0.00663, which was the best fit. Under the application of ultrasound, the average drying rate of wolfberry increased. Compared with natural drying, the polysaccharide content increased by 33.2 % at 250 mm irradiation height, and the total phenol content increased by 44.9 % at 40 kHz ultrasonic frequency. The antioxidant activity was the strongest, and the total flavonoids content was the highest (2.594 mg/g) at 24 W ultrasonic power. By comparing the microstructure of wolfberry under different drying methods, such as a fresh sample, natural drying, hot air drying, and ultrasonic-assisted drying, we found that the ultrasonic assistance increased the number of micropores on the surface of wolfberry, reduced the damage to epidermal cells, reduced the mass transfer resistance of the drying process and accelerated the drying process. This study shows that ultrasonic-assisted far-infrared drying technology played a significant role in the heat and mass transfer of wolfberry drying, and had great potential in the commercial processing of wolfberry.     

Effect of ultrasound on the techno-functional properties of food components/ingredients: A review

Ultrasound (US) has been used in many food systems and model systems, such as starch, whey protein concentrates and soy, to modify their chemical and techno-functional properties. At present, the use of ultrasound has yielded diverse results, ranging from potentiating the technological and functional properties of various foods to different operating conditions. Similarly, the results that were obtained vary according to the ultrasonic equipment used and the power, frequency and times of sonication, as well as the characteristics of the food system used. However, not all results have been favourable because US can cause damage to the structure of some food components, such as starch, and affect the technological and functional properties of the food. In the literature, there is little research on the effect of sonication on fibre; this gap in the literature is worrisome because fibre is found in a wide variety of foods and provides health benefits. Such research would represent an opportunity for researchers to make use of this technology for the generation of knowledge and improve the techno-functional properties in fibre, which could benefit the human population and the food industry. In this review, we present current results obtained with US in different treatments affecting processes of strong importance in the food industry, emphasizing the effects in the different model systems.     

Effect of surfactant addition on removal of microbubbles using ultrasound

It is difficult to control the bubble in a liquid by the external operation, because the behavior of the bubble is controlled in buoyancy and flow of liquid. On the other hand, microbubbles, whose diameter is several decades μm, stably disperse in static liquid because of their small buoyancy and electrical repulsion. When an ultrasound, whose frequency was 2.4 MHz, was irradiated, the milky white microbubbles suspended solution became rapidly clear. In this study, the effects of surfactant addition on the removal of microbubbles from a liquid in an ultrasonic field were investigated. The efficiency of removal of microbubbles decreased with surfactant addition. Surfactant type influenced the size of agglomerated microbubbles, and the efficiency of removal of microbubbles changed. The surface of microbubble was modified by surfactant adsorption, and the steric inhibition influenced the removal of microbubbles.     

Effect of ultrasound on the dissolution kinetics of phosphate rock in HNO3

Ultrasound is known to enhance solid/liquid reactions. This paper deals with the investigation of the dissolution of phosphate rock in nitric acid, in the absence and presence of ultrasound. The reaction is first-order with respect to H⁺ and activation energy equal to 16 kJ/mol in both cases. The effect of ultrasound is on the pre-exponential factor A. An empirical relation is given, which relates rate constant to ultrasound power.     

Effect of ultrasound on different quality parameters of apple juice

Fresh apple juice treated with ultrasound (for 0, 30, 60 and 90 min, at 20 °C, 25 kHz frequency) was evaluated for different physico-chemical, Hunter color values, cloud value, antioxidant capacity, scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical, ascorbic acid, total phenolics, flavonoids, flavonols and microbial characteristics. No significant effect of sonication was observed on pH, total soluble solids (°Brix) and titratable acidity of apple juice. Sonication significantly improved ascorbic acid, cloud value, phenolic compounds, antioxidant capacity, DPPH free radical scavenging activity and differences in Hunter color values. Moreover, significant reduction in microbial population was observed. Findings of the present study suggested that sonication treatment could improve the quality of apple juice. It may successfully be employed for the processing of apple juice with improved quality and safety from consumer’s health point of view.     

Effect of ultrasound and enzymatic pre-treatment on yield and properties of banana juice

Effect of ultrasound and enzymatic pre-treatments with cellulase and pectinase on yield and properties of banana juice were investigated. A two-level full factorial design was employed. The factors selected were ultrasonication time (0 and 30 min), cellulase concentration (0 and 0.2%) and pectinase concentration (0 and 0.2%). The responses studied were yield, viscosity, clarity, total soluble solids (TSS) and pH. It was observed that pectinase was more effective in increasing the yield of juice compared to cellulase. Ultrasonic pre-treatment alone did not significantly increase the yield of juice. When ultrasound was combined with pre-treatment with both the enzymes maximum yield of 89.40% was obtained compared to 47.30% in the control. The viscosity of the juice decreased with addition of enzymes and with application of ultrasound. The clarity of the juice was not affected by cellulase treatment, but improved with pectinase treatment. Ultrasonication alone was found to be more effective than pectinase or cellulase treatment in improving the clarity of the juice. The TSS increased with enzymatic treatment, ultrasonication and their combination. pH was not affected by treatment type, but was found to be lower for the treated juices. Significant correlations were observed between the various responses.     

Effect of viscosity on ultrasound wave reflection from a solid/liquid interface

A study of the simulated reflection of a wideband ultrasound shear wave from the solid/viscous fluid interface is presented. Various parameters affecting reflection factors including the material properties of the solid, fluid properties like density and viscosity, and the operating frequency are discussed. Simulated ultrasonic response waveforms are compared with the experimentally obtained data for NIST traceable calibration standards of viscosity. A good agreement was observed between the simulated and experimental waveforms at various viscosities and for different solid substrates.     

Effect of ultrasound-assisted sodium bicarbonate treatment on gel characteristics and water migration of reduced-salt pork batters

To study the potential usefulness of ultrasound (0, 30, and 60 min) and sodium bicarbonate (0 % and 0.2 %) combination on the reduced-salt pork batters, the changes in water holding capacity, gel properties, and microstructure were investigated. The pH, salt-soluble proteins solubility, cooking yield, and b* values of reduced-salt pork batters significantly increased (P < 0.05) with the increase in ultrasound time and the addition of sodium bicarbonate, leading to the hardness, springiness, cohesiveness, and chewiness significantly increased (P < 0.05). Furthermore, the use of ultrasound-assisted sodium bicarbonate treatment caused the reduced-salt pork batters to form a typical spongy structure with more evenly cavities. Due to the initial relaxation time of T₂₁ and T₂₂ were shorter, and the peak ratio of P₂₁ was increased and P₂₂ was decreased after ultrasound-assisted sodium bicarbonate treatment, implying that the mobility of water was reduced. Thus, the use of ultrasound-assisted sodium bicarbonate treatment enabled reduced-salt pork batters to have better gel characteristics and higher cooking yield.     

Effect of ultrasound irradiation on asphaltene aggregation and implications to rheological behavior of bitumen

The present work investigates the contribution of asphaltene aggregation to bitumen viscosity subject to ultrasound irradiation. A West-African bitumen with a viscosity of 12043 cP at room temperature was sonicated at low (38 kHz) and mild frequency (200 kHz) under controlled gas environment including air, nitrogen (N₂) and carbon dioxide (CO₂). The rheology of the bitumen, asphaltene content analyses as well as spectral studies were conducted. Herein was found that sonicating the bitumen at 200 kHz under air-environment reduces the initial viscosity up to 2079 cP, which was twice larger than that obtained when a low frequency was used. In respect of the gas environment, it was shown that ultrasound irradiation under N₂ environment could lower the bitumen viscosity up to 3274 cP. A positive correlation between the asphaltene content and the viscosity reduction was established. The results from the spectral analyses including Fast Fourier Infrared and the observations from Scanned Electron Microscope were consistent with the rheological studies and led to the argument that the viscosity reduction results from either the scission of long chain molecules attached to the aromatic rings (when the applied frequency was altered under fixed gas environment) or the self-aggregation of asphaltene monomers (when gas environment was changed at fixed frequency).