Use of ultrasound for the determination of flour quality

Within the baking industry, the control of dough properties is required to achieve final product quality and consistency. Traditional methods for dough testing are slow and off-line and do not provide fundamental rheological information. There is therefore a need for the development of fast and on-line instruments capable of providing relevant data for baking. Ultrasonics provide a non-destructive, rapid and low cost technique for the measurement of physical food characteristics.In this work, the water content of dough is investigated using ultrasonic techniques. The capability of ultrasound measurements for discriminating flours for different purposes is also studied. Doughs from more than 30 flours were characterised rheologically using a Chopin Alveograph and a Brabender Extensograph. Ultrasound measurements on the doughs prepared from these flours were also performed. The measurements were correlated, showing that ultrasound was an alternative measurement method to discriminate types of flours for different purposes.     

Ultrasonic study of wheat flour properties

In this work, the wheat flour properties are investigated using ultrasound techniques. Moreover, the flour samples were also characterized by means of well established techniques such as protein content, Alveograph and Mixolab®. A set of 35 dough samples, made of wheat flours with diverse physical and quality properties, were studied. The obtained results shown that ultrasound measurements can detect changes in the dough consistency induced by proteins and also by gelatinization of the starch. Furthermore, ultrasound measurements can be related to parameters indicative of the proteolytic degradation or softening of the dough due to protease activity. Thus, ultrasound can be considered a low cost and rapid tool, complementary to conventional test, for wheat flour characterization.     

Optimal design and experimental investigation of surfactant encapsulated microbubbles

The diagnostic capabilities of ultrasound imaging can be improved with contrast-specific nonlinear imaging modalities such as harmonic and subharmonic imaging. The nonlinear response of an encapsulated microbubble in an acoustic field is strongly influenced by the shell viscoelastic properties that are determined by the shell composition and thickness. In this paper, the subharmonic performance of a surfactant encapsulated microbubble was optimized by choosing the appropriate composition of shell material with the aid of theoretical model. To study the effects of viscoelastic properties of microbubble shell materials on the nonlinear scattered response of microbubbles, a theoretical model-modified Herring equation for the oscillation of encapsulated microbubbles in the ultrasound field was employed. Based on this model, a computer aided design system was developed to optimize and analyze the acoustic properties, particularly subharmonic responses, of microbubbles under different shell parameters. Furthermore, surfactant encapsulated microbubbles with different viscoelastic properties were prepared by changing the shell composition. Their shell viscoelastic behavior was measured indirectly as dilational modulus of monolayer film formed with surfactant molecular. Moreover, in vitro quantitative acoustic properties measurements of these microbubbles were carried out to evaluate their subharmonic performance. Both of the theoretical simulation and acoustic measurement showed that the surfactant encapsulated microbubbles with good subharmonic properties could be designed and prepared by adjusting the shell material composition with the guide of the computer aided design system.     

Effect of ultrasound-assisted resting on the quality of surimi-wheat dough and noodles

In this study, the influence of ultrasound-assisted resting at different power on the rheological properties, water distribution and structural characteristics of dough with 50 % surimi as well as the texture, cooking and microstructure characteristics of the surimi-wheat noodles were investigated. Compared with the fermentation control (FC) noodles, the microstructure, cooking and texture characteristics of noodles (≤24.00 W/L) were significantly (p < 0.05) improved after ultrasonic treating. As the increasing of ultrasonic power, compared to FC, the creep strain, recovery strain, semi-bound water, and free sulfhydryl (SH) contents of surimi-wheat dough decreased at first and then increased significantly (p < 0.05). The α-helix and β-turn content of dough increased at first and then decreased after ultrasonic treatment, while the β-sheet was reversed. The surimi-wheat dough network structure was improved by ultrasonic treatment, with the densest and continuous pore size in 21.33 W/L, but the dough structure was broken and loose (>21.33 W/L), which consisted of the hardness, elasticity, chewiness, resistant and cooked quality of surimi-wheat noodles. This work elucidated the effect of ultrasonic power on the performance of surimi-wheat dough, and the optimal ultrasound power was obtained, thereby improving the nutritional properties and the quality of surimi-wheat noodles.     

Assessment by MRI of local porosity in dough during proving. theoretical considerations and experimental validation using a spin-echo sequence

Proving is a key stage in the development of the final structure of bread, as invasive measurements may provoke dough collapse. Therefore, better understanding and better control of the nucleation and the growth of bubbles require the development of non-invasive methods of measurement. In the present work, a non-invasive method is presented for the measurement of local dough porosity from MR image analysis. For this, a direct relation between the gray level of a voxel and its gas fraction was established in the absence of heat and mass transfer. At whole dough scale for a one-dimensional expansion, the porosity estimated from the gray level was compared with the porosity estimated from total dough volume measurements in a range of [0.10, 0.74 m(3) of gas/m(3) of dough]. For short proving times (<30 min), MR image analysis underestimated porosity by a maximum of 0.03 m(3) of gas/m(3) of dough, but otherwise the difference between the two means of measurement was within the standard error of total dough measurements (+/-0.01 m(3) of gas/m(3) of dough). Maps of local porosity in dough during proving are also presented and discussed.     

Estimation of dynamic parameters of overthreshold parametric phase conjugation of ultrasound in magnetostrictive ferrites according to data of quasi-static measurements

A simple method for testing ferrite samples intended to be active elements of parametric phase conjugator of ultrasound was proposed and experimentally approved. The method allows one to estimate such dynamic parameters of parametric phase conjugator of ultrasound as the parametric amplification increment, threshold of absolute parametric instability, and optimum operating point position for a particular sample using results of measurements in a dc magnetic field. Results for two ferrite samples of different compositions and properties were compared to direct measurement data; their satisfactory agreement was obtained.     

Effect of ultrasound-assisted dough fermentation on the quality of dough and steamed bread with 50% sweet potato pulp

Ultrasound at an intensity of 17.5, 20.0, 22.5, 25.0 and 27.5 W/L was used to assist dough fermentation to prepare steamed bread with 50% sweet potato pulp (SB-50% SPP), which was compared with SB-50% SPP without ultrasonic treatment. The dough rheology, starch–gluten network, texture characteristics and sensory quality of steamed bread with different ultrasonic power densities (UPDs) were investigated. Dough samples at UPD of 22.5 W/L showed optimal viscoelasticity. The microstructure images exhibited that the content of starch particles wrapped in the gluten network increased significantly after sonication. In addition, the reduction in free sulfhydryl (SH) content and increase in wet gluten content after ultrasonic treatment led to significantly improved dough extensibility (p < 0.05). Results exhibited that the specific volume of SB-50% SPP increased by 13.93% and the hardness decreased by 21.96% compared with the control under UPD of 22.5 W/L. This study suggested that the application of ultrasound as a green technology to dough fermentation could lead to SB-50% SPP with good quality and sensory characteristics.     

Physicochemical properties of germinated dehulled rice flour and energy requirement in germination as affected by ultrasound treatment

Limited data are published regarding changes in the physicochemical properties of rice flours from germinated de-hulled rice treated by ultrasound. This work was undertaken to evaluate the effect of ultrasound treatment (25 kHz, 16 W/L, 5 min) on starch hydrolysis and functional properties of rice flours produced from ultrasound-treated red rice and brown rice germinated for up to 36 h. Environmental Scanning Electron Microscopy (ESEM) microimages showed that the ultrasound treatment altered the surface microstructure of rice, which helped to improve moisture transfer during steam-cooking. The flours from sonicated germinated de-hulled rice exhibited significantly (p < .05) enhanced starch hydrolysis, increased the glucose content, and decreased falling number values and viscosities determined by a Rapid Visco Analyzer. The amylase activity of the germinating red rice and brown rice displayed different sensitivity to ultrasonic treatment. The ultrasonic pre-treatment resulted in a significant reduction in energy use during germination with a potential to further reduce energy use in germinated rice cooking process. The present study indicated that ultrasound could be a low-power consumption method to modify the rheological behavior of germinated rice flour, as well as an efficient approach to improve the texture, flavor, and nutrient properties of steam-cooked germinated rice.     

Measurement of dynamic properties of viscoelastic materials

A new method for measurement of viscoelastic properties of materials, based on the exact solution of the problem of the forced oscillations of a flat sample loaded by inertial mass, is proposed. The device for these measurements is described. The elasticity modulus and loss tangent are measured within the frequency range from 100 Hz to 10 kHz at relative deformation of a sample below 1%. The approximate formulas for calculation of viscoelastic properties are derived, and the conditions of their applicability are determined. The methods for expansion of the frequency range and measurement of materials with extremely high loss tangent are proposed. The proposed method is compared with the current Standard. It is shown that the new method has the higher accuracy and expanded range of parameter measurements, and the construction of device is easy and reliable, since it does not require the knowledge on the oscillation properties of vibration source. The work was financially supported by the Russian Foundation for Basic Research (Grant No. 06-08-00193-a).     

Continuous monitoring of dough fermentation and bread baking by magnetic resonance microscopy

The consumer quality of baked products is closely related with dough structure properties. These are developed during dough fermentation and finalized during its baking. In this study, magnetic resonance microscopy (MRM) was employed in a study of dough fermentation and baking. A small hot air oven was installed inside a 2.35-T horizontal bore superconducting magnet. Four different samples of commercial bread mixes for home baking were used to prepare small samples of dough that were inserted in the oven and allowed to rise at 33°C for 112 min; this was followed by baking at 180°C for 49 min. The entire process was followed by dynamic T₁-weighted 3D magnetic resonance imaging with 7 min of temporal resolution and 0.23×0.23×1.5 mm³ of spatial resolution. Acquired images were analyzed to determine time courses of dough pore distribution, dough volume and bread crust thickness. Image analysis showed that both the number of dough pores and the normalized dough volume increased in a sigmoid-like fashion during fermentation and decreased during baking due to the bread crust formation. The presented magnetic resonance method was found to be efficient in analysis of dough structure properties and in discrimination between different dough types.     

Ultrasound response of viscoelastic changes of cellulose hydrogels triggered with Sono-deviced rheometer

Sono-deviced rheometer,which enabled viscoelastic properties under ultrasound operation, was used to investigate for cellulosic hydrogels. The viscoelastic behavior was compared in cellulosic hydrogels prepared at 0.5, 1 and 2 wt% concentration in the DMAc/LiCl solution. The sono-deviced equipment could measure the effect of changes in storage modulus G’ and loss modulus G” under 43 kHz ultrasound exposure. It was noted that the 43 kHz ultrasound significantly changed the values of the G′, meaning that the hydrogel was soften under the exposure within few seconds. When the ultrasound exposed 50 W of the out-put power at 1% strain, the G′ value of 4.2x10⁴ Pa was reduced to 4.0x10³ Pa during 5 min of the US interval. The declined lowering value of G’ then returned to the original moduli value when ultrasound was stopped. The values of both G’ and G” values were measured at applied strain % during viscoelastic measurements of the cellulosic hydrogels without and with ultrasound exposure. The comparison indicated that the ultrasound has reinforced the effect of the mechanical deformation of the hydrogel structure at the smaller mechanical strain values applied during the ultrasound operation. The ultrasound soften effect on the viscoelastic change efficiently occurred in the 0.5 wt% sample and easily induced the structural deformation probably due to the breakage of hydrogen bonds in the cellulose hydrogels.     

New image contrast method in magnetic resonance imaging via ultrasound

When applied to a sample, ultrasound (US) gives rise to a displacement of tissue and a flow in a liquid due to the acoustic radiation pressure. These movements depend on the viscoelastic properties of the sample and can be visualized precisely with an MRI scanner using diffusion- sensitive pulse sequences. In this paper, measurements will be presented, which show the visualization of the US under variation of its parameters in different liquids and in tissue.     

Estimation of shear wave velocity in gelatin phantoms utilizing PhS-SSOCT

We report a method for measuring shear wave velocity in soft materials using phase stabilized swept source optical coherence tomography (PhS-SSOCT). Wave velocity was measured in phantoms with various concentrations of gelatin and therefore different stiffness. Mechanical waves of small amplitudes (??10 ??m) were induced by applying local mechanical excitation at the surface of the phantom. Using the phase-resolved method for displacement measurement described here, the wave velocity was measured at various spatially distributed points on the surface of the tissue-mimicking gelatin-based phantom. The measurements confirmed an anticipated increase in the shear wave velocity with an increase in the gelatin concentrations. Therefore, by combining the velocity measurements with previously reported measurements of the wave amplitude, viscoelastic mechanical properties of the tissue such as cornea and lens could potentially be measured.     

Temperature mapping in bread dough using SE and GE two-point MRI methods: experimental and theoretical estimation of uncertainty

Two-dimensional (2D)-SE, 2D-GE and tri-dimensional (3D)-GE two-point T(1)-weighted MRI methods were evaluated in this study in order to maximize the accuracy of temperature mapping of bread dough during thermal processing. Uncertainties were propagated throughout each protocol of measurement, and comparisons demonstrated that all the methods with comparable acquisition times minimized the temperature uncertainty to similar extent. The experimental uncertainties obtained with low-field MRI were also compared to the theoretical estimations. Some discrepancies were reported between experimental and theoretical values of uncertainties of temperature; however, experimental and theoretical trends with varying parameters agreed to a large extent for both SE and GE methods. The 2D-SE method was chosen for further applications on prefermented dough because of its lower sensitivity to susceptibility differences in porous media. It was applied for temperature mapping in prefermented dough during chilling prior to freezing and compared locally to optical fiber measurements.     

Effect of ultrasound on structural and physicochemical properties of sweetpotato and wheat flours

Ultrasound technologies are increasingly used for modification of physicochemical properties of food systems. Effects of ultrasound (20 kHz, 750 W) up to 20 h on physicochemical properties of two varieties of sweetpotato flour were studied and compared with those of commercial wheat flour. Ultrasound induced structural modifications on starch granules mainly in the morphological changes of granules and reduction of the crystallinity. Longer treatment significantly decreased enthalpy change of gelatinization, pasting viscosities, gelling capacity, while increasing in vitro starch digestibility of raw flour. Besides, prolonged treatment reduced total phenolic contents and in vitro antioxidant activities of sweetpotato flours, mainly due to pyrolysis and release of hydroxyl radicals caused by cavitation. The extents of these changes were seen to depend on the treatment time and indicated degradation and modifications of the chemical components (e.g., starch and polyphenol) of flours. This study suggests that ultrasound processing as a non-thermal and energy-saving technique has potential to modify flour functionalities.     

Ultrasound-assisted fabrication of gluten-free dough for automatic producing dumplings

Nowadays celiac disease is becoming more common. It is the autonomic genetic disease that is accompanied by damage to the intestines due to a reaction to eating some proteins. People who are suffering from celiac disease cannot eat food containing gluten, including dough made from gluten-containing seeds. But the gluten-free dough has commonly bad rheological properties and cannot be used for automatic molding the dumplings. In this article, we propose the ultrasonic-assisted technology to fabricate the gluten-free dough with improved rheological properties acceptable for automatic molding of the dumplings. Application of ultrasonic treatment at a frequency of 35 kHz during the dough preparation leads to the homogenization of the dough structure and changing the rheological properties of the dough.The ultrasound induces mechanical, physical and chemical/biochemical changes of the dough components through cavitation. The sonication causes a doubled dough volume increase followed by an additional mass yield of the dumplings equal 2–10% per kilogram of dough. Besides extra beneficial economic effect, our technology provides an additional sterilization effect of the fabricated dough.     

Acoustic technique to monitor the kinetics of porous development phenomena in viscoelastic media

In this paper, the potential of a low frequency acoustic technique for the study and characterisation of viscoelastic porous media is investigated. This work was based on the limits of ultrasonic applications in highly absorbent porous media. In this context, fermenting dough was used as a model propagation medium. This type of product has a very complex matrix in terms of texture, openings and moisture. The basic theory of sound in such matter is recalled, especially the effects of the scattering of sound energy in matrices like that of the product under investigation. Depending on the properties of the openings, acoustic velocity and intensity of sound were chosen to represent the state of evolution of the matter. A tap-test acoustic technique was employed and allowed a quality indicator to be obtained. The results of the validation step using various technological parameters indicate that a high degree of sensitivity can be reached with non-destructive acoustic techniques.     

Studies on the use of power ultrasound in leather dyeing

Uses of power ultrasound for acceleration/performing the chemical as well as physical processes are gaining importance. In conventional leather processing, the diffusion of chemicals through the pores of the skin/hide is achieved by the mechanical agitation caused by the paddle or drumming action. In this work, the use of power ultrasound in the dyeing of leather has been studied with the aim to improve the exhaustion of dye for a given processing time, to reduce the dyeing time and to improve the quality of dyed leather. The effect of power ultrasound in the dyeing of full chrome cow crust leather in a stationary condition is compared with dyeing in the absence of ultrasound as a control experiment both in a stationary as well as conventional drumming condition. An ultrasonic cleaner (150 W and 33 kHz) was used for the experiments. Actual power dissipated into the system was calculated from the calorimetric measurement. Experiments were carried out with variation in type of dye, amount of dye offer, temperature and time. The results show that there is a significant improvement in the percentage exhaustion of dye due to the presence of ultrasound, when compared to dyeing in absence of ultrasound. Experiments on equilibrium dye uptake carried out with or without ultrasound suggest that ultrasound help to improve the kinetics of leather dyeing. The results indicate that leathers dyed in presence of ultrasound have higher colour values, better dye penetration and fastness properties compared to control leathers. The physical testing results show that strength properties of the dyed leathers are not affected due to the application of ultrasound under the given process conditions. Apparent diffusion coefficient during the initial stage of dyeing process, both in presence and in absence of ultrasound was calculated. The values show that ultrasound helps in improving the apparent diffusion coefficient more for the difficult dyeing conditions such as in the case of metal-complex dyes having bigger aggregate size compared to less difficult dyeing conditions.     

Rayleigh-Lamb wave propagation on a fractional order viscoelastic plate

A previous study of the authors published in this journal focused on mechanical wave motion in a viscoelastic material representative of biological tissue [Meral et al., J. Acoust. Soc. Am. 126, 3278-3285 (2009)]. Compression, shear and surface wave motion in and on a viscoelastic halfspace excited by surface and sub-surface sources were considered. It was shown that a fractional order Voigt model, where the rate-dependent damping component that is dependent on the first derivative of time is replaced with a component that is dependent on a fractional derivative of time, resulted in closer agreement with experiment as compared with conventional (integer order) models, such as those of Voigt and Zener. In the present study, this analysis is extended to another configuration and wave type: out-of-plane response of a viscoelastic plate to harmonic anti-symmetric Lamb wave excitation. Theoretical solutions are compared with experimental measurements for a polymeric tissue mimicking phantom material. As in the previous configurations the fractional order modeling assumption improves the match between theory and experiment over a wider frequency range. Experimental complexities in the present study and the reliability of the different approaches for quantifying the shear viscoelastic properties of the material are discussed.     

Sonographic evaluation of subacromial space

GOAL OF THE STUDY: The purpose of this study is to compare the accuracy of sonographic to radiographic measurements of subacromial space, and verify its variations in relation to acromial morphology, age, sex and rotator cuff pathologies. MATERIALS AND METHODS: As a result, we have compared a radiographic examination to sonographic examination, each measuring the subacromial space in 200 random shoulders, with a personal method. The sonographic examination was performed by using a HDI 5000 ultrasound scanner Sono-CT with 7.5 MHz linear array transducer. No stand-off pad was utilized. RESULTS: The statistical analysis of the data derived from the two measurements was not sufficient to conclude that the two techniques are different (p>0.8). They also correspond with the radiographic morphology of the acromion. The size of subacromial space was related to the acromial morphology, female gender, and rotator cuff pathology, however, it was not related to age. DISCUSSION AND CONCLUSIONS: Our results clearly show that sonographic measurements are very close to those obtained by X-ray (p>0.8). The Bland-Altman analysis showed that for all groups, the were small enough to give us confidence that the sonographic technique may be used in place of the radiographic one for clinical purposes. One-way ANOVA showed that sonographic measurements were statistically different among the four groups (p<0.05). The sonography demonstrated precision, accuracy and carefulness in the measurement of the subacromial space.