Preparation and characterization of water-in-oil emulsions loaded with high concentration of L-ascorbic acid

The present study was conducted to encapsulate higher concentration of L-ascorbic acid up to (30 g 100 mL(-1)) in the dispersed phase of water-in-oil (W/O) emulsions. Their continuous phase contained refined soybean oil or Moringa oleifera oil and a food-grade hydrophobic emulsifier. The volume fraction of the dispersed phase was fixed as to 30%. W/O emulsions with L-ascorbic acid retention greater than 95% were prepared using rotor-stator homogenizer at 7000 rpm for 5 min. The prepared W/O emulsions under this operating conditions had average droplet diameter of 2.0-3.0 mu m and coefficients of variation of 13%-22%. All the W/O emulsions were stable for more than 30 days at 4 degrees C or 25 degrees C with slight increase in average droplet diameter and without phase separation. Their L-ascorbic acid retentions were 50 g 100 g(-1) at 4 degrees C and 30 g 100 g(-1) at 25 degrees C after 30 days of storage. L-ascorbic acid retention ratio of the prepared W/O emulsions followed first-order kinetics with a good fit. (C) 2012 Elsevier Ltd. All rights reserved.