Search results for "Mass Transfer"
showing 10 items of 171 documents
Transfer of aroma compounds in water-lipid systems: binding tendency of beta-lactoglobulin.
1998
Interactions of volatile aroma compounds with protein in aqueous solutions, especially whey proteins, have received significant attention in recent years. This work attempts to improve our understanding of the mass transfer in multiphasic systems, such as emulsions at the lipid−water interface, and to reveal the role of β-lactoglobulin in the release rate of solutes. For this purpose the rotating diffusion cell has been used. From a practical point of view it enables evaluation of the transfer through the aqueous phase, through the oil and the interfacial transfer. The effect of β-lactoglobulin, medium pH, and solute concentration has been investigated. Benzaldehyde and 2-nonanone have been…
Membrane Deformation and Its Effects on Flow and Mass Transfer in the Electromembrane Processes
2019
In the membrane processes, a trans-membrane pressure (TMP) may arise due to design features or operating conditions. In most applications, stacks for electrodialysis (ED) or reverse electrodialysis (RED) operate at low TMP (<
Study of mechanical properties and mass transfer of agglomerated cork stoppers for sparkling wine conservation.
2019
The agglomerated cork stopper plays a key role in the preservation of sparkling wines because the gas exchanges (CO2 and O2) between the wine and the external environment depend on the stopper. The objective of this work is to determine the mechanical and barrier properties of agglomerated cork stoppers in order to identify the formulation parameters that can impact these properties, and highlight several critical points, which must be controlled during the process.The characterization of the agglomerated cork structure has revealed a large intergranular porosity, which is greatly reduced when smaller cork granules are used and when the cork is compressed in the bottleneck.The study of the …
Contribution à la compréhension de l'influence des paramètres de formulation et de procédé sur la structure et les propriétés fonctionnelle de films …
2012
The aim of this study is the analysis of structure and transfer mechanisms through chitosan based food packaging materials with incorporated carvacrol as a model of antimicrobial active substance. Integration of composition parameters, structure, processing and drying of chitosan systems is correlated to its physico chemical and functional properties. Understanding and detailed analyses of processing parameters is crucial in production of active chitosan coatings applied on conventional materials such as polyethylene. So, the knowledge of composition and microstructure in association to environmental conditions, control the retention and the release kinetics of carvacrol from chitosan film.…
Oxygen transfer performance of unbaffled stirred vessels in view of their use as biochemical reactors for animal cell growth
2012
Cultivation of microorganisms, plants or animal cells requires liquid agitation in order to ensure oxygen and nutrient transfer and to maintain cell suspension. However, In such suspensions both mechanical agitation and sparging aeration can cause cell death. Many studies on animal cell damage due to mechanical agitation and sparging aeration have shown that mechanical damage of freely suspended animal cells is in most cases associated with bursting bubbles at the air–liquid interface (Barrett et al., 2010, Nienow et al., 1996). Gas bubbles are usually generated by direct air sparging to propagate oxygen in a culture suspension. Mechanical agitation may also introduce gas bubbles to the cul…
From macroscopic to molecular scale investigations of mass transfer of small molecules through edible packaging applied at interfaces of multiphase f…
2009
Abstract This paper presents a multi-scale approach to investigate mass transfer properties of edible films that integrates some published data and new original results. The transport of small molecules, such as water, between the different parts of multiphase food products leads to quality deterioration and thus requires the use of barrier edible films or coatings. Therefore, it is necessary to characterise the properties of both food and edible barriers, like the diffusivities of their respective migrants. Surface properties characterisation of edible films, composed of an iota-carrageenan matrix in association with a high melting point fat was investigated by goniometry and allows the de…
Application of headspace analysis to the study of aroma compounds-lipids interactions
1998
Taking into account interactions between aroma compounds and food components is necessary to better manage the flavoring of food products. These interactions occur at a molecular level and reflect changes, at a macroscopic level, in thermodynamic equilibria, such as solubility or volatility. The rate of transfer of an aroma compound from the liquid to the vapor phase can be affected as well. The behavior of aroma compounds in water and lipid solutions was studied in two complementary ways, a thermodynamic and a kinetic approach (head-space analysis). The transfer rate of volatiles at the liquid-water interface does not only depend on the hydrophobicity of the aroma compounds. Vapor-liquid p…
Extraction of short peptides using supported liquid membranes
2002
Studies of extraction of short peptides using supported liquid membranes containing Aliquat 336 as a carrier are presented. The extractions are carried out from an aqueous donor phase with pH ≥ 10 to an acceptor phase containing salt. The mass transfer is driven by the gradient of salt concentration between these phases. The extraction efficiency is dependent on the composition of water phases, the type and concentration of counter-ion in the stagnant acceptor phase and the flow rate of the donor phase. Moreover, it is also influenced by the concentration and structure of the examined peptides.
Influence of Thermal Annealing on the Thermodynamic and Mass-Transfer Kinetic Properties of d- and l-Phenylalanine Anilide on Imprinted Polymeric Sta…
1999
An investigation of the material, chromatographic, thermodynamic, and kinetic properties of thermally treated (i.e., annealed) polymeric stationary phases imprinted with l-phenylalanine anilide (l-PA) was carried out. The imprinting procedure of the solid phase used in this study was the same as for the untreated imprinted stationary phase studied previously. However, after polymerization, these new stationary phases were treated at elevated temperatures (50, 120, 140, and 160 °C) for 24 h. The treatment at 120 and 140 °C led to a larger decrease in the retention of l-PA than that of d-PA. The polymer treated at 160 °C could no longer resolve the d,l-PA racemate. The heat treatments were ac…
Continuous fractionation and solution properties of PIB. II. CPF optimization
1987
The quality of polymer fractionation depends on the choice of the mixed solvent as well as on the particular conditions of operating the continuous countercurrent extraction. With a polyisobutylene (PIB) sample of medium molecular weight Mw = 98,400 g/mol and U = (Mw/Mn) − 1 = 1.4 plus the mixed solvents toluene/2-butanone (TOL/MEK) and n-heptane/2-butanone (HEP/MEK) (both giving comparably good fractionation in equilibrium experiments), possible ways to optimize the CPF were tested. The mixed solvent HEP/MEK turns out to be superior to TOL/MEK for kinetic reasons. Due to the larger gap between its density and that of the pure polymer, the coexisting phases can still move through the column…