Encapsulation of Menthol in Beeswax by a Supercritical Fluid Technique

Encapsulation of menthol in beeswax was prepared by a modified particles from gas-saturated solutions (PGSS) process with controlling the gas-saturated solution flow rate. Menthol/beeswax particles with size in the range of 2–50？μm were produced. The effects of the process conditions, namely, the pre-expansion pressure, pre-expansion temperature, gas-saturated solution flow rate, and menthol composition, on the particle size, particle size distribution, and menthol encapsulation rate were investigated. Results indicated that in the range of studied conditions, increase of the pressure, decrease of the gas-saturated solution flow rate, and decrease of the menthol mass fraction can decrease the particle size and narrow particle size distribution of the produced menthol/beeswax microparticles. An N2-blowing method was proposed to measure the menthol release from the menthol/beeswax microparticles. Results showed that the microparticles have obvious protection of menthol from its volatilization loss. 1. Introduction Natural menthol exists in peppermint and other mint oils, having minty odor. It is widely used as tobacco flavor to manufacture menthol cigarettes, inhibit stimulation from tobacco, and cover miscellaneous gases. However, the melting temperature of menthol is 42~43°C at atmospheric pressure, which makes it easy to sublimate. The high volatility not only means its short storage time and its pollution to the work environment and product line in the menthol cigarette production process but also suggests the flavor’s rapid loss with smoking. Obviously, the control and detection of menthol transfer is an important issue during the production, storage, and smoking of menthol cigarette. The encapsulation of menthol will not only provide coolness and refreshing taste from menthol but will also ensure controlled release of menthol; this may also improve the effectiveness, broaden the time range of menthol flavor, and ensure optimal dosage [1]. Hee [2] studied the transfer of menthol from tobacco to filter and the menthol percentages of different menthol cigarettes, indicating that adding menthol to the plate of paper instead of tobacco is the most effective method. Peng [3] studied the menthol composite particles by using phase separation-condensation method, and results showed that the composite particles with an encapsulation efficiency of menthol up to 58.7% could not only enhance the retention of menthol in the cigarette but also improve the smoke quality. In this study, the used wall material is beeswax, which has special fragrance of honey and