**2. Materials and Methods**

#### *2.1. Materials*

Zein from corn (~98%) was purchased from J&K Chemical Ltd. (Shanghai, China). Sodium carbonate (Na2CO3, ~99.8%) was purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Pectin from citrus peel was purchased from Shanghai Sangong Bioengineering Co., Ltd. (Shanghai, China). Chitosan (low molecular weight, 50–190 KDa) and quercetin (≥95%, HPLC) were purchased from Sigma-Aldrich Co. (Shanghai, China). Ultra-pure water obtained using a Milli-Q direct water purification system equipped with Quantum TEX column (Molsheim, France) was used throughout all the experiments.
