Development, characterization and in vitro antioxidant activity of chitosan-coated alginate microcapsules entrapping Viola odorata Linn. extract.

Viola odorata Linn or sweet violet has several biological activities due to the presence of flavonoids, tannins, alaloid, glycoside, and saponins. However, susceptibility of these compounds to harsh conditions and low solubility is a great challenge for their incorporation into food products. Therefore, encapsulation can be an effective approach in this respect. In the present study, chitosan-coated microcapsules loaded with Viola extract were prepared for the first time and the effects of independent variables (sodium alginate: 1-1.5%, calcium chloride: 0.6-1.5% and extract concentrations: 5-10%) on encapsulation efficiency (EE%) were investigated. After evaluation of the model, the optimum condition for preparation of microcapsules was selected as 1.47% sodium alginate, 5.02% extract and 1.42% CaCl2 with EE% of 83.21%. The microcapsules developed at this condition had an acceptable spherical shape and the results obtained in Fourier transform-infrared spectroscopy (FTIR) indicated the presence of the extract within the microcapsules. The mean diameters of the uncoated and chitosan-coated microcapsules were 73 and 141 μm, respectively. The in vitro release in acidic medium (pH 1.5) and phosphate buffer saline (pH 7) were 43.21% and 95.39%, respectively. The prepared extract-loaded microcapsules have potential to be used in food products providing acceptable antioxidant activity.