Stefania Mele

Quantitative characterization of phospholipids in milk fat via 31P NMR using a monophasic solvent mixture

The phospholipids (PL) occurring in both ewe and cow milk fat globule membrane were identified and quantitatively determined using 31P NMR spectroscopy with inverse gated decoupled sequences, which allowed a rigorous quantitative analysis. A strict relation between amount and distribution of PL and type of feeding was found. The method was calibrated over a mixture of PL standards. A recently introduced solvent constituted by a monophasic dimethylformamide/triethylamine/guanidinium hydrochloride solvent mixture was used. Compared to the traditional chloroform/methanol/water-EDTA solvent, the new solvent mixture shows very similar accuracy and precision from a quantitative point of view. The monophasic solvent overcomes the partition problems related to a biphasic system, and slightly enlarges the range of 31P NMR chemical shifts, thus improving the resolution. In addition, the new solvent apparently displays a lower chemical shift dependence on the various PL concentrations. The limit of the method is mainly determined by the formation of adducts between triethylamine and some PL, namely, PE, monomethylphosphati-dylethanolamine, phosphatidylethanolamine plasmalogens, and some lyso-PL. However, the new 31P NMR signals arising from these adducts could be easily quantified in the determination of PE.

Monoolein based liquid crystals to form long-term stable emulsions

Abstract In recent investigations of multicomponent systems it has been observed that, as almost a general rule, very stable emulsions can be obtained whenever a hydrophobic or a hydrophilic ‘solute’ is dispersed in a liquid crystalline matrix. Some examples are presented. Long-term stable w/o emulsions were prepared by dispersing water in the lamellar and reverse hexagonal phases formed by monoolein-based systems. All these three-phase emulsions (water, reverse hexagonal and lamellar liquid crystals) resulted kinetically stable, provided that the water solute was added gradually to a previously formed liquid crystalline phase.

Note: Fractionation of Sheep Milk Fat Via Supercritical Carbon Dioxide

Supercritical carbon dioxide (SC-CO2) was used for anhydrous ovine milk fat (AMF) fractionation. Two different fractions were obtained: a low molecular weight triacylglycerol (TAG), named fraction E, and a high molecular weight TAG, termed fraction R. Fractionation was performed at different pressure and temperature values. The effect of these parameters on the chemical composition of the two fractions were analysed in relation to the original AMF. Among the searched conditions, 250 bar and 40°C gave the best fractionation results.