Preparation of cinnamon essential oil emulsion by bacterial cellulose nanocrystals and fish gelatin

This study was aimed at preparing nanoemulsions with bacterial cellulose nanocrystals (BCNCs) and cinnamon essential oil (CEO) with and without fish gelatin. The effect of CEO concentration (0.2, 0.4, 0.8, 1.57, 2.34 and 3.1% v/w) and pH (3.5 and 5) on the droplet size, zeta-potential, morphology, and encapsulation efficiency (EE) of CEO/BCNC emulsions was investigated. It was observed that zeta-potential was approximately -25 mV for the BCNC emulsions, whereas it changed to positive values (from approximately 4 mV-12 mV) in the systems containing gelatin (3% w/w). In addition, in the presence of gelatin, emulsions exhibited larger droplets (450-1000 nm) than did the CEO/BCNC emulsions (350-550 nm), as demonstrated by transmission electron microscopy. TEM analysis also revealed the surfactant activity of gelatin, which displaced between the hydrophobic CEO nanodroplets and the more polar BCNCs. The effect of pH on EE was significant for the emulsions in the presence of gelatin in that EE was higher at pH 5 than at pH 3.5 up to a CEO concentration of 0.24% w/v. Finally, a direct relationship was established between CEO concentration and EE for emulsions with and without gelatin.