Effects of microfluidisation process on the amounts and distribution of encapsulated and non-encapsulated α-tocopherol microcapsules obtained by spray drying

The effect of microfluidisation on the amount of encapsulated and non-encapsulated α-tocopherol was evaluated in 21 different combinations of maltodextrin, gum arabic and α-tocopherol. A response surface design of two factors (α-tocopherol concentration: 17 to 28% and microfluidisation cycles: 0, 1 and 2) was applied for a purpose. It was determined that the initial amount of α-tocopherol showed a cubic effect on the maximum encapsulation efficiency according to the microfluidisation cycles used. A larger number of cycles in the microfluidiser decreased the size of the nanoemulsion at low initial concentrations (17-20%) of α-tocopherol. The distribution profile of α-tocopherol was also determined by Confocal Scanning Laser Microscopy, and the encapsulation efficiencies of all powders were correlated with their CIELAB parameter a* and resulted in a second-order relation. To the best of our knowledge, this is the first time that the image analysis is reported as useful non-destructive technique to correlate colour and encapsulated materials quantifications.