Amaltheys: A fluorescence-based analyzer to assess cheese milk denatured whey proteins.

The cheese industry faces many challenges to optimize cheese yield and quality. A very precise standardization of the cheese milk is needed, which is achieved by a fine control of the process and milk composition. Thorough analysis of protein composition is important to determine the amount of protein that will be retained in the curd or lost in the whey. The fluorescence-based Amaltheys analyzer (Spectralys Innovation, Romainville, France) was developed to assess pH 4.6-soluble heat-sensitive whey proteins (sWP*) in 5 min. These proteins are those that can be denatured upon heat-treatment and further retained in the curd after coagulation. Monitoring of sWP* in milk and subsequent adaptation of the process is a reliable solution to achieve stable cheese yield and quality. Performance of the method was evaluated by an accredited laboratory on a 0 to 7 g/L range. Accuracy compared with the reference Kjeldahl method is also provided with a standard error of 0.25 g/L. Finally, a 4-mo industrial trial in a cheese plant is described, where Amaltheys was used as a process analytical technology to monitor sWP* content in ingredients and final cheese milk. Calibration models over quality parameters of final cheese were also built from near-infrared and fluorescence spectroscopic data. The Amaltheys analyzer was found to be a rapid, compact, and accurate device to help implementation of standardization procedures in the dairy industry.

Water behavior revisited at the air/ionic solution and silica/ionic solution interfaces. Extension to coadsorption of ions and organic molecules.

This paper reports on investigations about the adsorption at the air-water surface, and for the sake of comparison at the silica-solution interface, of two 1-2 electrolytes, Pb(NO(3))(2) and PbCl(2), at first alone and then from a mixture with carbofuran or with benzene; all of them were at concentrations below 10(-2) M. The limited domain, where the Debye and Hückel formalism for solutions and the Wagner-Onsager-Samaras (WOS) model for surfaces are correct, is then respected. This study was aimed at trying to identify the part played in the surface by the different particles of the system components and in particular the role of water. When aqueous solutions of nonorganic salts are dilute enough, their surface tensions are known to be salt concentration-independent; however, the zero value of the resulting relative adsorption has never been the subject of analysis about water behavior. By combining experimental relative adsorptions and Gibbs excesses calculated from the WOS theory, we will show that, in well-known solutions such as KCl ones, where the negative excess in salt can be very precisely modeled by the WOS theory, the resulting water excess Gamma(W) is negative. The same result can be obtained by taking into account the Ray-Jones effect. This observation drove us to wonder about the results of a similar analysis done on solutions of unsymmetrical electrolytes and on mixtures of salt and organic molecules. Experiments showed that, for all of the systems, Gamma(W) was negative. For a given salt, Gamma(W) was more negative in the presence of organic molecules, and carbofuran was a more efficient water repellent than benzene; water repulsion was greater with nitrates than with chlorides. From these data, it seems that water was repelled toward the solution bulk, whereas ions probably took place between the bulk and a layer of organic molecules. These observations called for a more detailed modeling.

Coadsorption of carbofuran and lead at the air/water interface. Possible occurrence of non-volatile pollutant cotransfer to the atmosphere.

The weak solubility of carbofuran allows adsorption at the air/water interface. Carbofuran-rich layers can then induce the coadsorption of metallic salts such as lead nitrate; on the other hand, when carbofuran is missing, no adsorption of this salt takes place. This phenomenon was quantitatively studied through surface tension measurements under concentration conditions close to the environmental ones. Heavy metal salt adsorbed about ten times more than carbofuran. Evidence was then provided that the simultaneous presence of both pollutants in water favours their adsorption and passing from water to the atmosphere through mechanisms such as bubbling.

Surface phase diagrams: evidence of molecular arrangements at the aqueous-solution/solid interface.

Surface state changes described as phase transitions or simple molecular rearrangements have become a key issue in modern science. Indeed, they have an impact on the development of numerous (nano)technologies; they are also involved in biochemical and chemical mechanisms at the molecular level and also in environmental phenomena. At last, they have been at the origin of flourishing statistical descriptions that have illuminated new and very interesting aspects of surface behaviors. Here, to obtain still lacking coherent sets of experimental data on systems in which molecular interactions and thermodynamic properties are different, the adsorption behaviors of three aqueous mixtures in contact with a dense and homogeneous silica were studied versus concentrations and temperatures. Of course, these mixtures displayed very different bulk phase properties. Their stairlike isotherms are interpreted through surface phase diagrams; each of them is very similar to the corresponding bulk phase diagram. Their comparison gives new insights into the different surface states, the role of solvent in the surface, and the probable molecular mobility.