Synthesis and Characterization of Peppermint Oil Loaded Complex Coacervates of Chitosan Phosphate/κ-Carrageenan and Evaluation of their Antibacterial Activity

Abstract

Peppermint oil has been in use as traditional medicine for several common ailments besides being used as flavourings in foods and beverages. Like other essential oils it is also susceptible to oxidative degradation on exposure to oxygen, light and heat, which results in its decreased shelf life. Complex coacervation is a commonly used technique to encapsulate essential oils to give protection against degradation as well as providing a carrier vehicle for sustained release. In present work, the peppermint oil was encapsulated in a complex coacervate from a chitosan derivative, chitosan phosphate and κ-carrageenan in the presence of glutaraldehyde as crosslinking agent. The reaction conditions were optimized .The highest yield of the coacervate was recorded at pH 4.6 of the reaction medium and at a ratio of 2:4 by volume of 0.3% (w/v) solution of chitosan phospahate and κ-carrageenan. The effect of the variation of amount of crosslinker on the morphology and swelling property of the coacervate was also investigated and both the properties were found to be affected. A maximum loading efficiency of 84.19% was observed. The swelling and release studies revealed that both were pH dependent and release of peppermint oil from the coacervate showed a sustained release profile over a period of 72 h. The peppermint oil loaded coacervates were investigated for their antibacterial activities against Micrococcus luteus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia and Proteus vulgarus and found to be mildly effective against all of them.