Influence of rice bran stearin on stability, properties and encapsulation efficiency of polyglycerol polyricinoleate (PGPR)-stabilized water-in-rice bran oil emulsions

Abstract

In the present study, rice bran stearin was used to improve the physical stability and encapsulation efficiency of water-in-oil (W/O) emulsions fabricated from rice bran oil and polyglycerol polyricinoleate ester (PGPR). In the absence of rice bran stearin, the emulsions were highly unstable to phase separation with an oil layer forming on their surfaces. Phase separation was delayed by increasing the PGPR concentration because this reduced the water droplet size. Phase separation could be completely inhibited by replacement of 30 to 45wt% of rice bran oil with rice bran stearin due to the formation of a semi-solid fat crystal network that prevented droplet movement. Moreover, addition of rice bran stearin delayed the release of ferrous sulfate from the W/O emulsions. These results demonstrate that rice bran stearin can be used to improve the stability and encapsulation efficiency of W/O emulsions and reduce the level of PGPR required to stabilize them.