Zein as a water insoluble excipient for spray dry encapsulation of hydrophilic bioactives

Anti-solvent precipitation of zein was employed in conjunction with spray drying to reduce the usage of ethanol and to encapsulate the aqueous extract of green jelly leaf (Cyclea barbata Miers) antioxidants. Different concentrations of zein (0.35, 0.7, 1.05 and 1.4% w/v) and Hydroxypropylmethyl cellulose (HPMC) (5, 10, 15, 20% w/w) in several different formulations were investigated. The spray dried powders were characterised in terms of their encapsulation efficiency, morphology, average particle size and the antioxidant release. Result shows that encapsulation of green jelly leaf antioxidants using zein were possible with encapsulation efficiency between ~50 and 70%, where a higher concentration of zein in feed solution had favoured better encapsulation efficiency. The spray dried powder produced were relatively small (~6–10 μm) with spherical structure. The addition of HPMC also aided in delaying the agglomeration of zein nano-precipitates in the feed solution through its interaction with zein via hydrogen bonding. These results suggested that zein protein could have a potential application to encapsulate water soluble antioxidant for application in high water content food products.