Preparation of microemulsion of chitosan and green tea extract

Abstract

The water-in-oil (w/o) emulsion of green tea extract was prepared by dispersing the extract in mineral oil mixed with a mixture of two surfactants at the ratio of Span 80 to Tween 80 of 9:1 having an HLB value of 5.3, using a homogenizer with a stirring speed of 13,000 rpm, homogenizing time of 5 min to form a stable emulsion which was later stabilized by Tween 80. The emulsion of green tea extract was mixed with chitosan solution (MW 1.2 x 10⁵, 3.7x 10⁵ or 8.5 x 10⁵ Dalton at 87-88% deacetylation) at 1, 2 and 3% w/v. The mixture was mechanically stirred for 60 min. It was found that the viscosity of the chitosan emulsion increased as a function of chitosan concentration and molecular weight. The average size and zeta potential were found in the range of 124-275 nm and 16-51 mV, respectively. The hair surface was coated with chitosan emulsion. It was shown that the emulsion of green tea extract with chitosan at 3% w/v (MW 3.7 x 10⁵ Dalton) could coat hair surface as smoother as those obtained from the concentration of 1% and 2% w/v. The property of hair slip and ease of combing was determined by Texture Analyzer (TA) and Instron, respectively. It was found that 3% w/v (MW 3.7x 10⁵ Da) chitosan emulsion was the best condition for hair coating which yielded the highest slip and the easiest combing on hair surface. Besides, the higher the molecular weight of chitosan is, the lower slippery, feel, and ease of combing on hair surface.