Preparation and characterization of citrus essential oils loaded in chitosan microcapsules by using different emulsifiers

Citrus essential oils (CEOs) loaded in chitosan microcapsules (CS-CEOs) were prepared by 6 different emulsifiers (Tween 20, Tween 40, Tween 60, Tween 20/Span 801:1, Tween 20/SDBS1:1, Span 80) with emulsion-ionic gelation technique. Their rheological properties, embedding and release rate as well as microcapsules diameters were analyzed. The results indicated that emulsifier types significantly affected the size and embedding efficiency of microcapsules, obtaining sample groups of Tween 60, Span 80, Tween 20/Span 80 with typical diameters 289.3 nm, 3893.2 nm, 8843.2 nm, respectively. The structures and thermal properties of CEOs microcapsules were analyzed by using fourier transform infrared spectrophotometry (FT-IR), X-ray diffractometry and differential scanning calorimetry (DSC). Results demonstrated that CEOs oil were successfully embedded in the microcapsules and group of Tween 60 has the minimum particle size with the best embedding rate of 68.1%. The strength of the intermolecular interaction as well as exothermic peaks of microcapsules prepared with different emulsifiers were different, Tween 60 holds the lowest temperature value of exothermic peak for smallest internal energy is needed for melting, corresponds with its lowest particle size. Fourier transform infrared spectroscopy (FT-IR) provided profiles on the major functional groups of CS-CEOs. The results proved condition to prepare CS-CEOs microcapsules by using different emulsifiers.