A modified premix method for the emulsification of spearmint essential oil (Mentha spicata) by ceramic membranes

Abstract A versatile and innovative membrane emulsification system that utilizes a modified premix method was investigated for preparing oil/water emulsions from spearmint essential oil. The modified method (forced-air premix, FAP) is based on flowing air in parallel to the surface of the ceramic membrane at the permeate side, and it was compared to a traditional premix method (conventional premix, CVP) in which pressure was applied only to the feed stream. The influence of membrane pore size, transmembrane pressure, and airflow velocity on the oil emulsion properties was evaluated. In the FAP method, the air stream forces the early shearing and detachment of oil droplets right after the premix permeates the membrane. The results showed that the increase in the operating pressure resulted in the reduction of droplet size and span values for all membranes and methods evaluated. The higher surfactant concentration and presence of forced airflow influenced the reduction of the droplet size and dispersion of emulsions in the FAP method. Stable emulsions were obtained which 28 days of storage.