Optimization of the production conditions of primary (W1/O) and double (W1/O/W2) nano-emulsions containing vitamin B12in skim milk using ultrasound wave by response surface methodology

The main objective of this study was to the fortification of skim milk with encapsulated vitamin B(12)in Water in Oil in Water (W-1/O/W-2) emulsions. Vitamin B(12)was loaded to the water phase of W-1/O emulsion formulated by 10-30% inner water phase (W-1) in W-1/O emulsion (Wt%) and 6-10% polyglycerol polyricinoleate (PGPR) in oil phase through sonication for 4-6 min. Then, 5-25% of primary W-1/O emulsions were dispersed into skim milk by sonication for 1-5 min to produce W-1/O/W(2)emulsions. The smallest droplets and the lowest polydispersity index (PDI) were obtained in the W-1/O emulsion formulated by 20% W(1)and 9% PGPR by sonication for 6 min. Optimization of W-1/O/W(2)emulsion formulations was carried out using response surface methodology (RSM) according to the results of encapsulation efficiency, droplet size and PDI. The 88.85% encapsulation efficiency was obtained in W-1/O/W(2)emulsion formulated 12% W-1/O in W-1/O/W(2)emulsion by sonication for 1 min, in which the droplet size and PDI were 57.144 nm and 0.19, respectively. Another optimized formulation of W-1/O/W(2)emulsion via 79.70% encapsulation efficiency, the droplet size of 65.29 nm, and PDI 0.21 produced by using 10% of W-1/O in W-1/O/W(2)emulsion through sonication for 2 min. No phase separation was observed in two optimized emulsions during 7 days storage at 37 degrees C. However, the droplet size, sedimentation index, and PDI of two optimized W-1/O/W(2)emulsions were increased, and their encapsulation efficiency was decreased during storage.