ORIGINAL TITLE: INTERPRETATION OF MICROMIXING EFFECTS ON FAST CONSECUTIVE-COMPETITIVE REACTIONS IN SEMI-BATCH STIRRED TANKS BY A SIMPLE INTERACTION MODEL

Liquid-liquid equilibrium data for two ternary systems were obtained. The experimental data were measured for cyclohexane-toluene-sulfolane at 17, 25 and 50°C, and for hexane-toluene-sulfolane at 18 and 25°C. The NTRL and UNIQUAC models were used to correlate the experimental results and to calculate the phase compositions of the ternary systems. The agreement between the experimental results and the fitted values was equally good with both of the models.     

A SYSTEM FOR RECORDING DEFORMATIONS IN TEXTURE TESTS*

An instrumental technique is described for recording food deformation in texture tests. The time required for the applied force to change between two levels is accurately recorded in digital form. Constant deformation rates are used so that deformation is directly proportional to time. The new readout is demonstrated with springs and selected foods to indicate its performance and show the inaccuracies that occur when using strip-chart recorders to measure deformations. The response of the new system is adequate to test products with a deformability up to 3400 g mm^-1 at deformation rates up to 100 cm min^-1 with less than 3 % error.     

Fractionation of Anhydrous Milk Fat by Superficial Carbon Dioxide

Milk fat was fractionated with supercritical CO₂ (SC-CO₂) into 8 fractions at temperatures of 50° and 7O°C, over a pressure range of 100–350 bar. Two fractions (L1 and 2) were liquid, 3 fractions (11–3) were semi-solid and 3 fractions (Sl-3) were solid at 20°C. The peak melting temperature progressively increased (9.7° to 38.3°C) from fraction L1 to S3. The concentration of short chain (C24-C34) triglycerides decreased from fraction L1 to S3 while that of long chain (C42-C54) triglycerides increased gradually. The medium chain triglycerides were more concentrated in fractions L2 and 11–3. The proportion of short (C4-C8) and medium (ClO-C12) chain fatty acids decreased and that of long (C14-C18) chain fatty acids increased gradually from fraction Ll-S3. The weight average molecular weights and geometric mean-carbon number of milk fat fractions were in the range from 625.6 to 805.0 and 34.2 to 47.6, respectively, in comparison to 729.3 and 41.O, respectively, for native milk fat, suggesting SC-CO₂ effected a fair degree of molecular weight separation.     

MAGNETIC RESONANCE IMAGING STUDIES of the FREEZE-DRYING KINETICS of POTATO

Subzero temperature NMR Imaging of the nonfreezing water in potato cylinders is used to study freeze-drying kinetics. the analysis of the distribution of transverse relaxation rates of the samples between +5C and -25C is used to determine the state of water in potato tissue and establish imaging protocols. the evolution of the Residual Water Content, the diameter of the frozen core observed visually and of the nonfreezing water detected by NMR Imaging, are monitored as a function of the freeze-drying time. These results are interpreted with a theoretical model based on pure sublimation from the surface of a finite cylinder.     

Fatigue strength analysis of notched aluminium specimens using the highly stressed volume method

This paper describes a methodology to analyse the fatigue strength of notched aluminium 7075 T7531 specimens using the highly stressed volume method. A straightforward test setup was developed to load test samples with different stress concentrations in repeated bending at high frequency. The highly stressed volumes are precisely determined using static finite element analysis in combination with Matlab for post‐processing. Mean values of the local endurable stress amplitudes are calculated by means of the staircase method. The results indicate that the highly stressed volume can be used as an accurate and efficient design parameter to take the notch‐effect in aluminium components into account.     

MECHANISMS UNDERLYING THE ROLE OF FRICTION IN ORAL TEXTURE

The role of friction in food texture sensations are reviewed with the focus on results from our own laboratory, concentrating on texture sensations that are affected by the lubricative properties (e.g., roughness and creaminess), by the viscosity (e.g., melting and thickness) and by the used thickeners (e.g., airiness and heterogeneity). A food's lubricative properties are affected by its fat content, fat droplet size, particle size and shape and thickener. Foods with lower fat contents, larger fat droplets, larger particles and specific thickeners exhibited higher friction while their creaminess and fattiness sensations, associated with good lubrication, are reduced. Roughness and dryness sensations, associated with poor lubrication, are increased. Taste and flavor compounds also affected these texture sensations, albeit via a different mechanism. Specific compounds can affect the lubricative properties of saliva resulting in friction‐related sensations, such as astringency. Astringent compounds interact with proline‐rich proteins in saliva, causing precipitation that may be sensed as discrete particles and/or increased roughness. Alternatively, the compounds may precipitate dead cells and other debris present in saliva. Astringent compounds may also directly affect the surface properties of the oral mucosa.     

DESIGN AND OPTIMIZATION OF HEAT EXCHANGERS FOR BATCH HEATING BY THE NTU-EFFECTIVENESS METHOD

A design method has been developed for sizing external heat exchangers for batch processes based on the effectiveness-NTU method. The method is applicable to any heat exchanger configuration and design. Based on the specified process conditions a solution is obtained which directly specifies the required batch circulation rate and the associated heat exchanger effectiveness. This approach is particularly useful for those types of heat exchanger designs which permit explicit sizing.