Determination of oxygen transmission barrier of microcapsule wall by crocetin deterioration kinetics

Microencapsulation was a widely used technique for the unstable materials because the wall prevented the core from contacting with oxygen. To improve the stability of crocetin and maximize the protection afforded by the wall, in the present study, microencapsulation was applied for crocetin by spray-drying the first time with three wall materials (beta-cyclodextrin, gum arabic and maltodextrin). The oxygen transmission barrier was proposed to evaluate the potential gas barrier of these wall materials, and it was measured by the deterioration kinetics of crocetin. To enhance the oxygen transmission barrier of the wall, the major conditions of spray-drying and the storage were investigated. Results showed that the deterioration rate followed the first kinetic model closely. Spray-drying was applicable to microencapsulating crocetin with the microencapsulation efficiency of 77.91-85.03 % under the inlet air temperature 210 A degrees C. The oxygen pressure in the microcapsule was reduced to < 0.114 +/- A 0.005 atm for all the three wall materials. The oxygen transmission barrier of the wall microencapsulated by the three materials was qualified by thermodynamic parameter activation energy (29.436 +/- A 0.080, 58.813 +/- A 0.312 and 49.376 +/- A 0.125 kJ/mol, respectively). Gum arabic was the most suitable agent for microencapsulating crocetin, and a dry environment was preferred for its storage because the low relative humidity was beneficial to the stable structure of the microcapsule. This study would be helpful to the industrial application of crocetin.