Optimization of the conditions for producing water-in-oil-in-water microemulsions and spray-dried microcapsule of tomato extract powder

Abstract The objective of this study was to investigate optimized conditions for producing water-in-oil-in-water (W/O/W) microemulsions and spray-dried microcapsules of tomato extracts. The condition of highest yield for W/O/W microemulsification was optimized by response surface methodology (RSM). The independent variables were ratio of tomato extract to MCT (X 1: 1:9-2:8), concentrations of emulsifier (X2: 0.50-1.00), and ratio of W/O to secondary aqueous coating material (X 3: 1:5-1:9). According to the RSM results, the ratio of tomato extract to MCT at 1.24:8.76 (v/v), concentration of emulsifier at 1.00% (w/v), and ratio of W/O phase to secondary aqueous coating material of 1.00:6.16 (v/v) were found to be the optimal conditions for producing microemulsion of tomato extracts. At these conditions, the yield of W/O/W microemulsion determined as approximately 99.69%. After optimizing the conditions for producing microemulsion of tomato extract by RSM, the emulsion was spray-dried. The average particle size ( D(4,3)) and zeta-potential value of the spray-dried microcapsules under optimized condition were approximately 5 µm and -29.68 mV, respectively. Results of the present study provide practical information on optimum conditions for producing W/O/W microemulsions and spray-dried microcapsules of tomato extracts.