Formulation and Optimization by Experimental Design of Low-Fat Mayonnaise Based on Soy Lecithin and Whey

The main objective of this study is to develop a new formula for a diet mayonnaise-like sauce without cholesterol. Emulsifying power is provided by the use of soy lecithin and the total fat content was limited to 16%. Droplet size measurement of employed mayonnaise samples at different times show that the largest diameter of fat does not exceed 18.5 µm with a yield stress of 56.1 Pa. Results of stability to centrifugation reveal that the absence of the supernatant oily layer ensures the stability of the emulsion. Using the experimental design method, the number of trials can be limited to a number of 16 experiments, and best formulation of the mayonnaise (without cholesterol) was obtained

Spectres de diffusion Raman du monocristal de thiourée dans les phases para-et ferroélectrique constantes de forces intermoléculaires

Polarized Raman spectra of oriented single crystals of thiourea have been recorded in the paraelectric phase (V) and in one of the two ferroelectric phases (I). The fundamentals of the crystal have been assigned. Strong changes are induced by the phase transition. Intermolecular force constants have been calculated for some vibrational states of the molecule in the lattice.Nous avons obtenu les spectres de diffusion Raman en lumière polarisée du monocristal de thiourée dans la phase paraélectrique (V) et une de ses phases ferroélectriques (I). Les vibrations fondamentales du cristal ont été interprétées à l'aide de la méthode de corrélation. Le changement de phase s'accompagne de modifications très importantes du spectre. Les constantes de forces intermoléculaires ont été calculées pour divers états vibrationnels de la molécule dans la maille cristalline

A risk assessment approach to evaluating food safety based on product surveillance

This paper outlines a risk assessment approach to food safety evaluation, which is based on testing a particular type of food, or group of similar foods, for relevant microbial pathogens. The results obtained are related to possible adverse effects on the health of consumers. The paper also gives an example of the way the risk assessment approach may be used in practice. The proposed system seeks to provide information on the exposure of consumers to microbial pathogens when the food is consumed. It reflects the successful application of good manufacturing practices and HACCP principles on the part of the producer, as well as the effect of consumer handling of the product, on the exposure rate. The information obtained on factors affecting exposure to microbial hazards and their impact on consumers would allow risk management and communication to be carried out effectively. A practical example is presented concerning the risk assessment of Bacillus cereus in pasteurized milk. © 1998 Elsevier Science Ltd. All rights reserved

Extension of linear stability analysis for the dynamic stretching of plates: Spatio-temporal evolution of the perturbation

International audienceBeing able to predict fragment distributions in terms of speed and size, following the fracture of thin metallic shells subjected to dynamic expansion, is of major importance for civil and military applications. For ductile metals, this fracture process is initiated by plastic flow instability resulting in necking, i.e. the occurrence of local thinnings where the plastic deformation is localized. Since decades, linear stability analyses have been carried out to study the multiple necking formation via a perturbation of the fundamental state. The underlying assumption related to the linear stability analyses developed so far is the time scale separation (meaning that the development of the instability is much faster than the evolution of the fundamental state), see Fressengeas and Molinari (1994) or Shenoy and Freund (1999). The aim of the work is to propose an extended linear stability analysis which can tackle situations where the time scale separation hypothesis is no more satisfied (i.e. at very large strain rates). The proposed methodology is exemplified by considering the dynamic extension of a plate under plane strain condition; the material behavior being modeled adopting various constitutive laws from rate insensitive to thermo-viscoplastic ones. The role of initial perturbation (or defect) is discussed. While the role of the initial conditions is important at the early stage of the deformation process, their influence on the growth rate and on the dominant mode are negligible at large strain for moderate loading rate. One main feature of the proposed model is the estimation of the amplitude development of each mode. A strong difference in the amplitude predictions is revealed between the new model and the classical linear stability analysis of the literature, even if the growth rates are comparable for both approaches at late deformation stage. However, history effect related to the amplitude of a given mode, originating from the early stage process, may lead to strong amplitude differences which remain visible at the late stage. The benefit of the new theory is the fact that the spatio-temporal evolution of the mechanical and thermal parts of the perturbation can be captured naturally, even for cases where the plastic flow is initially stable and becomes unstable as the deformation progresses

Synergistic temperature and ethanol effect on Saccharomyces cerevisiae dynamic behaviour in ethanol bio-fuel production

International audienceThe impact of ethanol and temperature on the dynamic behaviour of Saccharomyces cerevisiae in ethanol biofuel production was studied using an isothermal fed-batch process at five different temperatures. Fermentation parameters and kinetics were quantified. The best performances were found at 30 and 33°C around 120 g l-1 ethanol produced in 30 h with a slight benefit for growth at 30°C and for ethanol production at 33°C. Glycerol formation, enhanced with increasing temperatures, was coupled with growth for all fermentations; whereas, a decoupling phenomenon occurred at 36 and 39°C pointing out a possible role of glycerol in yeast thermal protection

Extension of 1D linear stability analysis based on the Bridgman assumption. Applications to the dynamic stretching of a plate and expansion of a ring

International audienceThe analysis of multiple necking phenomenon during dynamic stretching of a metallic plate is investigated. For that purpose, a new 1D linear stability analyses is proposed to capture the perturbation evolution. The multidimensional aspect of the stress field within the neck region is taken into account with a Bridgman correction factor. The novelty of the 1D approach is to let the time evolution of the perturbation determined by the linearized field equations. So, no predefined time dependency is assumed as in classical 1D linear stability analysis of the literature, see Zhou et al., An elastic-visco-plastic analysis of ductile expanding ring, Int. J. Impact Eng., 2006. The proposed model, named hereafter 1D-XLSA (standing for 1D-eXtended Linear Stability Analysis), can also be viewed as the restriction to 1D of the 2D-XLSA model developed in Xavier et al., Extension of linear stability analysis for the dynamic stretching of plates: Spatio-temporal evolution of the perturbation, European Journal of Mechanics-A/Solids, 2020. A comparison for a thermo-viscoplastic material with strain hardening is proposed for three possible routes : a 1D model based on the frozen coefficient theory named 1D-CLSA (standing for 1D-Classical Linear Stability Analysis), the proposed 1D-XLSA and 2D-XLSA models. It is shown that while growth rates in late deformation stage are similar, a strong difference in amplitude exists due to large discrepancies in the early deformation stage. The comparison also illustrates the importance of the modeling of multiaxiality of the stress field within the neck region and of initial defects. While differences between models are limited for perturbations with small wavenumbers, large discrepancies are observed for perturbations with large wavenumbers. Our model is also derived for the case of the extension of a cylindrical bar which is representative of the ring expansion during dynamic loading

Etude prospective du coude de la gymnaste de haut niveau par IRM : à propos de 26 cas

Dépistage des lésions du coude chez les gymnastes (syndrome d'hyperutilisation du coude). L'IRM permet une évaluation claire des traumatismes épiphysaires, mais ne dépiste pas les lésions à un stade infraradiologique

Calibration procedures of the Tore-Supra infrared endoscopes

International audienc