Interactions and antioxidant stability of sesamol in dry-emulsions
Abstract
Dry emulsions prepared from saccharose (SAC),
Labrafil M 1944 CS, sesamol (SEOH), and hydroxypropylmethylcellulose
(HPMC) or sodium caseinate (SC)
by grinding or dissolution, and different desiccation techniques
(spray (SD)- or freeze (FD)-drying, or heating at
60 C) were investigated to determine possible interactions
between mixture components. The goal of this study was to
determine the best formulation which will regenerate perfectly,
after water dilution of dry emulsions, the initial liquid
emulsion with the same characteristics that before drying.
The morphological state of SAC and dry emulsions were
determined by scanning electron microscopy analysis (SEM)
analysis. Glass transition temperature, and melting (endothermic),
decomposition (endothermic), oxidation (exothermic)
peak temperatures and enthalpies were measured by
differential scanning calorimetry (DSC). The antioxidant
activity of emulsions was evaluated through their ability to
reduce 1,1-diphenyl-2-picrylhydrazil (DPPH) free radical.
SEM analysis showed that SD-prepared, SC-containing dry
emulsions formed better spherical particles with smooth
surface at about 5 lm diameter as compared to emulsion
containing HPMC. These former emulsions also showed
more thermal stability by DSC. The combined results of the
three analytical techniques emphasized the importance of the
dry emulsion process regarding the efficiency and the thermal
stability of antioxidant substances. A specific physical
and/or chemical combination (such as hydrogen bond) sufficiently
stable, at about 150 C, could be suggested when the
technique used for dry emulsion preparation was SD. After
water dilution, this dry emulsion obtained from quaternary
mixture: SAC, Labrafil, SEOH and SC, will regenerate the
initial liquid emulsion with the same characteristics that
before drying.