Nanoliposomal thyme (Thymus vulgaris) essential oil: Effects of formulation parameters

Essential oils with antimicrobial or antioxidant activities have received extensive attention among customers, manufacturers, and food scientists, especially with rising worries about the safety of synthetic food preservatives. However, like other functional lipid compounds their incorporation into aqueous systems is challenging, due to their less water solubility. Furthermore, their susceptibility to light, moisture, heat, and oxygen origins their less chemical and structural stabilities. Consequently, the present research was aimed to encapsulate the thyme essential oil into nanoliposomes, using a thin layer hydration-sonication technique, which can be a proficient solution for revealed problems. The effects of phospholipid and stabilizing agents' concentrations, namely, lecithin, cholesterol, and glycerol, as main formulation parameters were investigated on characteristics of gained nanoliposomes, using a response surface method. Various empirical models were also developed to predict product characteristics by changing the formulation parameters. According to the numerical multiple optimizations, the best thyme oil nanoliposomes can be gained using equal concentrations of all three components as 1% with a mean particle size of 189.6 nm, PDI of 0.3487, the net zeta-potential of 42.48 mV, and DPPH radical scavenging of 12.72%. The prepared nanoliposomes had acceptable physical but limited chemical stabilities. The antibacterial action of manufactured essential oil nanoliposomes against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus has made them efficient candidates as natural food preservatives.