2.3.2. Loading Efficiency and Loading Capacity of Quercetin

Quercetin-loaded hollow zein and hollow zein-chitosan particles were centrifuged at 2000× *g* for 15 min to remove unencapsulated quercetin, and the supernatant and samples were diluted 50-fold in ethanol for the measurement of quercetin absorption at a λmax of 373 nm using a UV1800 UV-Vis spectrophotometer (Shimadzu Corporation, Tokyo, Japan) with a standard curve constructed from 1 to 20 μg/mL of quercetin dissolved in ethanol (a correlation coefficient of 0.999, Figure S4), adopting the method of Wang et al. [22]. Samples were prepared in triplicates for each measurement. Loading efficiency and capacity of quercetin in the particles were determined by the following equations.

$$\text{Loading efficiency} \left( \% \right) = \frac{\text{Queretion in supernantant}}{\text{Total added queue}} \times 100 \tag{1}$$

$$\text{Loading capacity} \left( \% \right) = \frac{\text{Quercetin entrapped in particles } \left( \mu \text{g} \right)}{\text{Zein and chipsan } \left( \mu \text{g} \right)} \times 100 \tag{2}$$
