Effect of oil in emulsion and homogenization pressure on the microencapsulation of basil oil

摘要

Microencapsulation of flavors is the technology of converting liquid flavor materials into easy-to-handle solids. It also provides protection against degradation reactions and prevents the loss of volatiles compounds. The capsule wall material along with the emulsion properties (i.e. viscosity and droplets size) and the drying process conditions are some of the responsible factors for the flavor retention during the encapsulation process. The objective of this work was to evaluate the influence of oil concentration and homogenization pressure on the emulsion properties and oil retention during the microencapsulation of basil essential oil by spray drying, using gum Arabic as wall material. Experiments were planned according a 2~2 central composite design. The independent variables were total oil concentration with respect to total solids (10 – 25%) and homogenization pressure (0 – 100MPa) and the analysed responses were droplet size, emulsion viscosity and oil retention in the microcapsules. The increase in the homogenization pressure up to 50 MPa decreased the emulsion droplet size. However, the use of pressures above 85MPa resulted in the formation of droplets with larger size. The homogenization pressure, as well as the oil concentration, had no effect on viscosity. Since the use o gum Arabic as wall material results in the formation of emulsions with low viscosity (in the order of 0.08 Pa.s), no significant reduction in emulsion viscosity is obtained with the use of different homogenization pressures. Oil retention was positively affected by the homogenization pressure and negatively affected by the oil content. Higher flavor loads resulted in poorer flavor retention. Microencapsulation of basil essential oil using gum Arabic as wall material showed to be a suitable process to obtain powdered flavors. It is possible to obtain higher oil retention with the use of lower oil concentration in the emulsion and higher pressure.