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A new application of a high sensitivity magnetoelastic resonator able to measure period and damping constant of low frequency torsional oscillation is described and validated by experimental tests. The sensitive parameter is the amplitude of resonant magnetoelastic waves in the soft ferromagnetic core (Fe 62.5 Co 6 Ni 7.5 Zr 6 Cu 1 Nb 2 B 15 amorphous ribbon). The theoretical model of the device has been developed, correlating torsional oscillations to the friction force applied by the fluid in which they occur. Thus, an accurate indirect evaluation of fluid viscosity has been demonstrated. The main prerogative of the proposed sensor is to work without contact with the oscillating mechanism. As experimental validation, viscosity of UHT milk was measured versus different fat content. The experimental comparison with a standard rheometer demonstrates the new device competitiveness in the measure of low viscosity fluids at low share rate. Moreover, the detected behaviors at increasing temperature are in agreement with previous literature. In perspective, the new magnetoelastic resonators application can be very ductile and effective in on-line monitoring of viscosity change with time to control composition, degradation or contamination of liquids.

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The objective of this work is to better understand how the structural parameters (particle content, particle size and serum viscosity) influence the rheological properties of apple purees. An apple puree (called “native”) was ground to obtain dispersions with three different particle size distributions. This mechanical treatment induced the separation of parenchyma irregular cell clusters into regular single cells, modifying both the morphology and the particle size distribution of purees. A separation–reconstitution step made it possible to obtain samples with a wide range of insoluble solids (8–24 g/kg). Pectin was added to some of the samples in order to increase the viscosity of the continuous phase. The rheological behaviour and structural properties of the modified apple purees were investigated using flow and oscillatory rheological measurements, particle size measurements and confocal laser scanning microscopy. Rheological properties such as apparent viscosity, yield stress and elastic modulus decreased as particle size decreased and they increased as insoluble solids content increased. Modelling of rheological properties with master curves made it possible to take into account the apparent relative volume occupied by the particles of different sizes.

This work presents the continued development of an autonomous portable system for measuring the Wobbe number (calorific content) of gases for the purpose of determining the quality of natural gas. Past research has shown the Wobbe number can be determined if the dynamic viscosity is known. The sensor described here operates on this principle and is essentially a gas viscometer. The sensing components are integrated into single low temperature co-fired ceramic (LTCC) device making the sensor compact and low cost. The sensor was placed within a compact enclosure with data acquisition electronics and was connected to a PC from which a LabVIEW program controls the sensors operation and records the data. It is an evolution of previous work where the sensor concept was proven using a non-integrated system. Preliminary results show the sensor could operate autonomously and was stable when measuring the viscosity of air.

An enzymatic membrane reactor based on an enzymatic membrane elaborated by immobilizing a lipase on a ceramic support was used to perform interesterification between castor oil triglycerides and methyl oleate. As substrates solution is highly viscous, viscosity was reduced by injecting supercritical CO2. After the validation of the concept, the influence of different operating parameters as regards performance has been checked. The effect of the pore size of the ceramic support on which the enzyme is deposited has been looked at. Operating pressure was proved to be a key parameter as it highly influences productivity. The objective of this work is to report attractive results on this process which opens interesting prospects in a field where at the present time there are very few valuable technologies. © 2007 Elsevier B.V. All rights reserved.

Dehydration of meat by soaking in a concentrated solution of water, salt and corn syrup (DE21) generally results in a high water loss and moderate salt and sugar gains. This study was undertaken to better understand the role of corn syrup in the transfer of water and solutes, and particularly its limiting effect on salt impregnation. Corn syrup is composed of saccharides of molecular mass varying from 180 Da (glucose) to more than 1500 Da (oligo- and poly-saccharides), in variable proportion. In an attempt to clarify the role of these different saccharides on mass transfer, immersion trials in concentrated solutions of salt (constant molality = 3.0) and polyethylene glycol (PEG, used a model solute) of varying molecular mass and molality were carried out. The influence of solution viscosity was also studied through the addition of agar agar as a viscosity agent. Results showed that water loss increased while salt and PEG gains decreased with increasing molecular mass of PEG in the range of 200-600 Da. In addition, an increasing molality of PEG from 0.6 to 1.6 mol/kg water led to increases in water loss and PEG gain but a decrease in salt gain. Under the prevailing experimental conditions, no significant influence of solution viscosity on mass transfer was found. Moreover, immersion trials were carried out to compare corn syrup with three different combinations of PEG with molecular mass distributions similar to that of corn syrup. The mixtures closely reproduced corn syrup behaviour with respect to salt gain. However, their impact on water loss and PEG gain (as compared to sugar gain) was significantly different from that of corn syrup. Information gathered in this study was used to propose a schematic representation of the mechanisms involved in the transfer of water and solutes during the immersion of meat in a ternary solution. The model is based on the development of a barrier layer of solutes at the periphery of the product, this barrier playing a key role in the control of subsequent mass transfer. © 2006 Elsevier Ltd. All rights reserved.

Colour and texture are important features of amala, a traditional thick paste obtained from dry yam flour. Tubers from eight yam cultivars were blanched at 65 °C for 20 min and dried at 40 °C for 5 days to test biochemical, thermal and pasting changes occurring during traditional yam flour processing. Blanching reduced peroxidase activity and drying reduced polyphenoloxidase activity, but total phenol content and the brown index of flour and of amala increased dramatically during the latter operations. The brown index of amala was significantly correlated with the total phenol content of the flour (r=0.84) and the peroxidase activity of the fresh tubers (r=0.75). Amylose content and starch gelatinization enthalpy remained stable. For all cultivars, drying significantly increased the onset gelatinization temperature, suggesting the occurrence of starch annealing. The latter leads to a reduction in swelling power and solubility during pasting, and hence to a lower paste viscosity.

From the K-L model proposed by Lewellen [LEW 77], an analytical expression of turbulence macroscale L was established. This expression, obtained with the hypothesis of a zero horizontal pressure gradient can be used for inertial or Couette flow. This formulation is better than the classical linear expression and in good agreement with numerical computations. We obtain a new solution for the velocity profile which can be compared with the logarithmic profile.