Alginate/Shellac beads developed by external gelation as a highly efficient model system for oil encapsulation with intestinal delivery

Abstract

The aim of this study was to evaluate the potential of the alginate/shellac combination as wall material (WM) to develop an oil encapsulation system by external gelation. The Taguchi method, a powerful process optimization tool, was used to determine the optimal process conditions in which to prepare beads with a high oil encapsulation efficiency (EE). The effect of the variables: sunflower oil concentration in the emulsion (E[oil]: 30 and 50 %w/w), emulsion/wall material ratio (E/WM: 80/20 and 20/80 %v/v) and concentration of calcium chloride (CaCl2: 5 and 15 g/L) on the EE were evaluated. The bead morphology, the total oil content of beads (OCB), mean particle size, sphericity factor (SF) and swelling degree (Sw) were also investigated. Finally, the optimal alginate/shellac beads were submitted to in vitro digestion. The results showed that the beads formed under optimal conditions reached an EE value of 98.7% and OCB of 38.6%. The oil concentration in the emulsion was the variable that most affected the oil EE. The beads obtained were semi-spherical, smooth-surfaced, non-aggregated, with a particle size of 2.13 mm and SF of 0.08. The Sw of the developed alginate/shellac beads was unaffected at acid pH values; however, beads showed swelling under basic conditions (pH 7). The optimal beads showed more oil released during intestinal digestion than during gastric digestion. These findings have important implications for oil encapsulation and the design of delivery systems of oil soluble compounds, which are useful in the food industry for developing novel products containing health-promoting bioactive compounds.