Descrição
Digital image processing (DIP) is a powerful tool that can be used to describe the loss of
emulsion stability by molecular diffusion or coalescence. The stability of salad dressings (lemon
juice and extra virgin olive oil) microencapsulated with biopolymers (without sorbitol) was
analyzed by fluorescence DIP for a 110 days period. The emulsions were stored both
refrigerated (4ºC) and at room temperature (27ºC). In addition, sorbitol was added to a
formulation stored under refrigeration and was monitored for 21 days. About 100 images were
processed and more than 5.000 objects were counted in each analysis. Throughout the
experiment time about 99% of the samples presented were roundness, ensuring that the
objects accounted by DIP were, in fact, micelles. The average diameter of the fresh emulsions
(EP) was higher than the reconstituted lyophilized emulsions (RLE). Moreover the RLE
maintained at room temperature presented an average diameter larger than the samples stored
at 4ºC throughout the 110 days. In fact, whereas approximately 45-65% of the micelles of the
emulsion stored at room temperature presented a diameter between 0.1 and 1.0 Cm, the
emulsions kept at 4ºC presented higher percentages for this size range, indicating an increased
stability of these samples. In both cases the majority of the micelles are in the sub-micron
range. Furthermore, the DIP showed a greater stability for the refrigerated RLE with time
throughout the experiment. Regarding the sorbitol influence, the emulsion containing sorbitol
presented smaller micelles (in diameter) than without, considering both EP and RLE. During the
studied period it was not possible to assure which destabilization (molecular diffusion or
coalescence) process occurred.
; Ferreira, E. C. 
