Microencapsulation of flax oil was investigated using zein as the coating material. Central Composite
Design e Face Centered was used to optimize the microencapsulation with respect to zein concentration
(x1) and flax oil concentration (x2) using spray drying. Also, freeze drying was carried out at two zein:oil
ratios. The quality of microcapsules was evaluated by determining encapsulation efficiency, flowing
properties (Hausner ratio), and evaluating the morphology with scanning electron microscopy. The
response surface model for microencapsulation efficiency showed a high coefficient of determination
(R2 ¼ 0.992) and a non-significant lack of fit (p ¼ 0.256). The maximum microencapsulation efficiencies
were 93.26 0.95 and 59.63 0.36% for spray drying and freeze drying, respectively. However,
microcapsules prepared by spray and freeze drying had very poor handling properties based on the
Hausner ratio. The bulk density decreased with an increase in zein concentration at the same flax oil
concentration. The morphology of the flax oil microcapsules depended on the zein:flax oil ratio and the
process used for microencapsulation. Flax oil microcapsules prepared by spray drying appeared to be
composed of heterogeneous spheres of various sizes at high zein:flax oil ratios. Microcapsules prepared
by freeze drying resulted in agglomerated small spheres. These microcapsules might find a niche as
functional food ingredients.
2