Effect of carrier blend proportion and flavor load on physical characteristics of nutmeg (Myristica frangrans Houtt.) oleoresin microencapsulated by spray drying

The effect of proportion of maltodextrin and gum arabic as carrier material and the percentage of nutmeg oleoresin as flavor load on microencapsulation by spray drying was studied. The proportions of 0, 20, 40 and 60 percent gum arabic (w/w) in the carrier blend and 10, 20 and 30 percent nutmeg oleoresin (w/w) as flavor load were studied. Emulsions were microencapsulated in a vertical co-current spray drier equipped with a rotary wheel atomizer operated at 18000 rpm. The inlet air temperature was set at 190 ± 2oC. The microcapsules formed were then analyzed for their physical characteristics. Flavor load was found to have no influence whereas blend proportion was found to influence the moisture content. True density increased until 40% gum arabic and decreased thereafter. Solubility increased with increase in flavor load and blend ratio. Though the highest encapsulation efficiency of 74.8% was obtained at a flavor loading of 10% at a carrier proportion of 40% gum arabic, further decrease was marginal with increase in flavor load up to 20%. Considering the product characteristics, a 40% gum arabic in the carrier blend and a flavor loading of 20% nutmeg oleoresin were found to be optimum. The micrographs of optimum combination showed uniform spherical powder without surface dents and a central void with microdrops distributed in the solid matrix.