Wako 1st grade

The co-precipitation method using β-CD was applied according to the methodology described by Ayala-Zavala et al.⁵¹ with a few modifications. A total of 2.5 g (±0.01 g) of β-CD (Wako 1st Grade, FUJIFILM Wako Chemicals, Japan) were dissolved in 50 mL of a co-solvent of ethanol and distilled water (1 : 2 v/v) mixture at 55 °C (±2 °C) and 700 rpm on a hot stirrer plate. In addition, another co-solvent was prepared with 0.1 g (±0.01 g) oil-in-water emulsifier gum Arabic (referred-to as “GA” hereafter) (AMC. CO., Japan) added with the aim of increasing the dispersibility of EOs in the co-solvent. After cooling the co-solvent to 45 °C, 2 mL of the eeHCP(SEEP) was added dropwise using a syringe. Subsequently, the mixture was stirred at 45 °C (±2 °C) for 2 h and then maintained overnight at 4 °C (±2 °C). The cold precipitates (supposed to be β-CD-eeHCP(SEEP) and β-CD-GA-eeHCP(SEEP) capsules) were recovered via the suction filtration and rinsed with 60% ethanol to remove the residual eeHCP(SEEP), and then the capsules were dried in a desiccator at 23 °C for 72 h and stored in an airtight glass at 23 °C before subsequent characterization. As a control, blank β-CD capsules without the addition of eeHCP(SEEP) were prepared in the same condition and steps as mentioned above.