The Preparation And Properties Of Three Types Of Micro Encapsulations Of Sweet Orange Oil Using Alginate-Chitosan As Wall Material

In this study, three kinds of microencapsulations of sweet orange oil was prepared through orifice method with sodium alginate and chitosan as wall materials. Tested and compared microencapsulations’ morphology, encapsulation efficiency (EE), loading capacity (LC) and release characteristic, and analysis ing the influences on the structure and property of microencapsulations after adding chitosan respectively.Firstly, the preparation of calcium alginate (CA) gel beads. At first, the influences of sodium alginate concentration, CaCl2 concentration, ratio of wall material to core material on microencapsulations’ morphology was analysised through pre-single factor experiment, and selected the optimum range of them. And then, the preparation conditions were optimized by orthogonal experiments L9 (34) using encapsulation efficiency (EE) as the target index. The result showed that the optimum sodium alginate concentration, CaCl2 concentration, ratio of core material to wall material and kind of emulsifying agent were found as 2%(w/v),1.5% (w/v),1.5:1,0.1%(w/v) tween 80 with 0.1%(w/v) glyceryl monostearate respectively, for which the EE was highest to 76.1%.Secondly, under optimization of the calcium alginate (CA) gel beads’preparation, added chitosan to prepare chitosan-coated calcium alginate (CCCA) and chitosan-calcium alginate complex (CCAC) gel beads according to complex coacervation. Designed pre-single factor experiments for CCCA and CCAC gel beads respectively, which was about the influences on microencapsulation’s surface smoothness and pitting of acetic acid concentration and chitosan concentration. The result showed that:to some extent, the smoothness of CCCA and CCAC gel beads increased with increasing chitosan concentration, while the pitting increased with increasing acetic acid concentration.Finally, the structural characterization and properties characterization of three kinds of microencapsulations. These microcapsules had a closely size, about 1.9mm, and having a smooth surface. The surface smoothness in descending order were CCAC, CA, CCCA gel beads successively, and all of them had a smaller size after dried. For CCCA and CCAC gel beads, there are also pitting on their surface. The EE in descending order and the release rate in increasing order were CCAC, CCCA and CA gel beads, while the LC in descending order was CA, CCAC and CCCA gel beads.The result showed that:sodium alginate could be used to embedding sweet orange oil to prepare microencapsulation with high EE, regular shape and good release characteristic. Chitosan had a great influence on microencapsulation’s structure and property. So, through controlling parameter, these three types of microencapsulations could be choosed and used in chewing gum, puffed food and other food products to control release and prevent volatilization because of their different characteristic or property.