Bulg. J. Phys. vol.31 no.3-4 (2004), pp. 96-110

Evaluation of Short-Term and Long-Term Stability of Emulsions by Centrifugation and NMR

S. Tcholakova1, N. Denkov1, I. B. Ivanov1, R. Marinov2
1Laboratory of Chemical Physics & Engineering, Faculty of Chemistry, Sofia University, 1164 Sofia, Bulgaria
2Laboratory "Liquid Crystals", Institute of Solid State Physics, Bulgarian Academy of Sciences, 72, Tzarigradsko Shaussee Blvd., 1784 Sofia,
Abstract. The effect of storage time on the coalescence stability and drop size distribution of egg yolk (EY) and whey protein concentrate (WPC) stabilized emulsions is studied. The emulsion stability is evaluated by centrifugation, whereas the drop size distribution is measured by means of NMR and optical microscopy. The experimental results show that there is no general relation between the emulsion stability and the changes in the mean drop diameter upon shelf-storage of protein emulsions. On the other hand, it is shown that the higher short-term stability, measured by centrifugation immediately after emulsion preparation, corresponds to higher long-term stability (after their self-storage up to 60 days) for emulsions stabilized by the same type of emulsifier. In this way, we are able to obtain information for the long-term stability of emulsions in a relatively short period of time.

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