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This article investigates the effect of sucrose addition on the formation of casein gels by acidification and/or renneting of pure micellar casein. Gelation kinetics and gel properties were followed by rheological methods, and microscopy and syneresis measurements were used to obtain a more complete characterization of the structures formed. Sucrose content has been identified as a key parameter for controlling the kinetics of aggregation and the strength of the final gels. Results have shown that the effect of sucrose on gelation can vary such that effects can be completely reversed depending on the gelation route used. During acid gelation, addition of up to 30% (wt/wt) sucrose causes gels to form more rapidly and at higher pH values, and to have higher viscoelastic moduli and a more homogeneous microstructure than those without sucrose. By contrast, gels formed by renneting in the presence of sucrose are weaker and have longer gelation times. It is proposed that sucrose reduces solvent quality and causes the collapse of the "hairy" kappa-casein brush on the surface of the casein micelles. This may explain why sucrose increases the possibility of gel formation during acidification and reduces the degree of kappa-casein hydrolysis during renneting.

Phase equilibria of milk protein/locust bean gum systems in high levels of sucrose were investigated to understand the behaviour of these components in diary products and also to look at the particular effect of sucrose. Two milk protein systems were investigated, skimmed milk (SMP) and native phosphocaseinate (PCN). The main advantage of using this latter sample is that it is representative of the casein micelles of milk and allows understanding of what happens in a model system with controlled sugar and salt content. At a temperature of 5°C, pH 6.8, and at an ionic strength of 0.08 M, these mixtures tend to phase separate because of high incompatibility. The similarity between the behaviour of SMP/LBG and micellar casein/LBG systems is evident, suggesting that the incompatibility between skimmed milk and locust bean gum is largely attributable to the incompatibility of micellar casein and locust bean gum. Ternary phase diagrams, in the absence or presence of 20%, 30% or 40% (w/w) sucrose, were established and compared. Sucrose has only a slight influence on the thermodynamic compatibility. The addition of sucrose leads to a concentration effect on the protein phase and dilution of the locust bean gum phase. Some rheological and turbidity measurements, as well as observations using confocal laser scanning microscopy and electron microscopy, were carried out and demonstrated that for the concentrations, temperatures and times investigated, there is no interaction between the components. The microstructures of mixtures have also been investigated in order to study the concentration effect of each biopolymer as well as the sucrose effect. It was clearly demonstrated that the microstructure is driven by the phase volume ratio and this probably leads to a difference in mechanical properties.

The stability of dairy emulsions containing both proteins and polysaccharides is mainly controlled by the nature of the protein–polysaccharide interaction. This work describes the behaviour of a micellar casein/locust bean gum (LBG) model system, and examines the effect of adding sucrose. For such systems a very high incompatibility has been demonstrated leading to thermodynamic separation into two distinct phases, one rich in protein and the other in polysaccharide. The second virial coefficient approach described by Edmond and Ogston was adopted to clarify the effect of sucrose on the micellar casein/LBG phase diagrams.

Oxidation of hydrogen (0.1–2.0% v/v) in air over supported palladium catalysts at 300–625 K and atmospheric pressure has been investigated using a microcalorimetric method. The kinetics are influenced by reactor design, with activated processes at low temperatures and diffusion-limited rates at high temperatures. The mechanism involves a surface layer of PdO and weakly adsorbed H 2 . Water causes inhibition and reversible deactivation, particularly at low temperatures. The reaction is strongly inhibited by bromomethane (0.1–1.0% v/v) which competes with hydrogen for adsorption sites.

Polysaccharides are widely used in the dairy industry as stabilising, thickening and gelling agents and locust bean gum (LBG) is one of the most commonly used. Together with the milk proteins, they form a pseudoternary milk protein-polysaccharide-water solution. The aim of this study was to build up a more detailed thermodynamic and kinetic understanding of molecular interactions between milk protein and LBG and to look especially at the effect of sucrose. Ternary phase diagrams in absence or in presence of sucrose (20, 30 or 40% w/w) were established and compared. For such a system, a very high degree of incompatibility has been demonstrated leading to thermodynamic separation into two distinct phases, one rich in protein and the other in polysaccharide. The similarity of a Skimmed milk (SMP/LBG and a micellar casein/LBG system suggests also that the incompatibility between skimmed milk and LBG is largely attributable to the incompatibility of micellar casein and LBG. Sucrose appears to have only a modest influence on the thermodynamics of these mixed systems, leading to a concentration effect within the protein phase and a dilution within the locust bean gum phase. Data on the effect of sucrose on the individual components suggests, however, an improved solvent effect for LBG. It has been clearly demonstrated that the microstructure of these systems is driven by the phase volume ratio.

α-Galactosidase I from Vicia faba seeds binds to potato starch and sheep erythrocytes. With the aid of fluorescence microscopy and using 4-methylumbelliferyl α- D -galactoside as the substrate it has been demonstrated that the binding is via the lectin sites of the enzyme leaving catalytic sites free and detectable. The lectin site is specific for D -glucose/ D -mannose residues.