Optimization of nanocapsules preparation by the emulsion-diffusion method for food applications

The aim of this work was to establish the conditions to obtain polymeric nanocapsules containing food ingredients by the emulsification-diffusion method. The Response Surface Methodology was used to optimize the process. The variables studied were shear rate (3070-18,920 s(-1)), polymer-wall concentration: poly-epsilon-caprolactone (PCL, 100-300 mg), and stabilizer concentration: polyvinyl alcohol (PVAL, 25-100 g/L). The analyzed responses were particle size (PS), polydispersion index (PM), density (rho(nc)), and zeta potential (zeta). The results of rho(nc) and micrographs confirmed the presence of capsular structures. The most efficient conditions to obtain nanocapsules were 10,917 s(-1), 50 g/L of PVAL and 256 mg of PCL, predicting a response of PS = 250 nm, rho(nc) = 1.021 g/cm(3), PDI = 0.045, and zeta = -20.02. It was concluded that keeping the same preparation conditions, the formation of nanocapsules is also possible from other food oily materials with similar characteristics (predicting values PS approximate to 300 nm and zeta approximate to -25). The proposed nanocapsules may have application in food preservation and storage. (C) 2010 Elsevier Ltd. All rights reserved.