CONTROLLED RELEASE OF L-TRYPTOPHAN AND VITAMIN-B2 FROM MODEL WATER OIL-WATER MULTIPLE EMULSIONS

Stability and nutrient release from model water/oil/water (W/O/W) multiple emulsions based on kerosene oil, Span 80 and Tween 20 were studied. Multiple emulsion internal and external droplet sizes were approximately 1 and 7.5 mum respectively. The initial encapsulation yield was 92-98%. The apparent yield stability decreased to 85-87% after heating at 80-degrees-C for 20 min. The release of a nutrient. L-tryptophan (L-Trp) or riboflavine-5'-monophosphate (Vitamin B2), from the W/O/W multiple emulsions was found to conform to first order kinetics for studies performed at pH 2-10. The rate of release was generally greater near the isolectric point of L-Trp or Vitamin B2. The permeability coefficient for nutrient release was in the range 0.32-1.92 x 10(-10) cm/s. This was 10(5)-10(6)-fold lower than the estimated permeability coefficient for water transfer across a W/O/W multiple emulsion oil phase. Therefore, we conclude that processes of nutrient release and water transfer within a W/O/W multiple emulsion occur via different routes.