Molecular encapsulation of citral or d-limonene flavor by spray drying

Lemongrass oil and d-limonene are typical flavor oils used in the food and cosmetic industries. Lemongrass oil displays some therapeutic properties such as analgesic, antimicrobial, fungicidal, deodorant, etc. Citral, the main active component of lemongrass oil, consists of a mixture of two isomeric acyclic monoterpene aldehydes: geranial and neral. Molecular encapsulation of these flavors was investigated by spray drying. Cyclodextrin (CD) and modified starch were used as encapsulants that made up the wall material of the spray-dried powders. CD can control flavor release rate and protect the encapsulated flavor from volatilization by the formation of inclusion complex. CD content in the wall material affected the morphology, flavor retention, and flavor stability of the spray-dried powders. d-Limonene and citral in lemongrass oil encapsulated within the matrix of CD were the most stable. However, the retention of dlimonene and citral was the highest in their respective wall materials of pure modified starch and highly branched cluster dextrin (HBCD). Microscopy of the spray-dried powders revealed that hollow structure of the powders was influenced by the content of cyclodextrin in the wall material. The inclusion complexation ability of β-CD could possibly remedy the inefficiency of Capsul in protecting the encapsulated citral against oxidation over time due to its “leaky” structure.