*2.1. Reagents and Apparatus*

ImjectTM Alum Adjuvant (No. 77161) was obtained from Thermo Scientific Inc. (Pittsburgh, PA, USA). Ovalbumin (OVA) was obtained from Sigma-Aldrich Inc. (Saint Louis, MO, USA). BCA protein assay kit was obtained from Beyotime Biotechnology Co., Ltd. (Shanghai, China). Goat anti-mouse IgE antibody and HRP-labeled donkey anti-goat IgG antibody were obtained from Abcam Inc. (Cambridge, UK). DAB peroxidase substrate kit was purchased from Solarbio Co., Ltd. (China). The HPLC-grade acetonitrile, methanol, ammonium formate and formic acid were obtained from Fisher Scientific (Pittsburgh, PA, USA). Ultrapure water was collected from Millipore Milli-Q system (Bedford, MA, USA). Cellulase (400 U/mg), pectinase (500 U/mg) and papain (800 U/mg) were obtained from Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Ultrafiltration centrifugal tube (15 mL, 10 kDa) was purchased from Millipore Inc. (Bedford, MA, USA). Other reagents were purchased from Sigma-Aldrich Inc. (Saint Louis, MO, USA).
