Encapsulation is the process by which one material or mixture of materials is coated with or entrapped within another material or system. The encapsulation of flavors serves to retain the aroma in a food product during storage, protect the flavor from undesirable interactions with food, minimize flavor/flavor interactions, guard against either light-induced reactions or oxidation, and to effect a controlled release. This occurs at a later state during processing, storage or final preparation prior to consumption.
Spray drying largely dominates the market for the encapsulation of flavors. Carbohydrates, such as hydrolyzed starches, emulsifying starches and gums (essentially gum acacia), serve as the most common carrier materials. Hydrolyzed starches include maltodextrins and corn-syrup solids. These materials are inexpensive, bland in flavor, very soluble (up to 75%), and exhibit low viscosity in solution. Their major shortcomings are a virtual lack of emulsifying capacity and marginal retention of volatiles.16 Hydrolyzed starches vary greatly in protecting encapsulated flavors from oxidation. There is a strong dependence of oxidative stability on the dextrose equivalent (DE) of the product. Because of this, oxygen uptake decreases as DE increases. They may be labeled natural only if produced via enzymatic hydrolysis.
Emulsifying starches have been partially hydrolyzed and derivatized to impart lipophilic properties. The lipophilic group added to the starch backbone comes from the reaction with 1-octenyl succinic anhydride at a 0.02 degree of substitution.12,5 These modified starches provide excellent volatile retention and emulsification properties.8,27 Their main drawbacks include potential off-flavors, higher cost, and poor flavor protection against oxidation.16 In addition, modified starches are not considered natural and may not be permitted for food use in some countries.