Epigallocatechin gallate egcg

Caffeine standards were purchased from Beijing Weiye Research Institute of Metrology and Technology (Beijing, China). The reference standards, decanoic acid ethyl ester, theanine, catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), epicatechin gallate (ECG), gallocatechin gallate (GCG), and epigallocatechin gallate (EGCG), were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Alkane standard solutions (C8–C40) for linear retention index (RI) calculations were obtained from TanMo Quality Testing Technology Co., Ltd. (Beijing, China). Internal standard solutions were prepared in dichloromethane prior to use. Ultrapure water was prepared with a Barnstead GenPure Pro system (Thermo Fisher Scientific, Waltham, MA, USA).

(−)-Epigallocatechin gallate (EGCG, 98% purity) was purchased from Yuanye Biotechnology Co. Ltd. (Shanghai, China). Mmembrane syringe filters (0.22 μm) were purchased from Dingguo Changsheng Biotechnology Co. Ltd. (Beijing, China). An ultrasonic dental scaler was from Guilin zhuomuniao Medical Devices Co. Ltd. (Guilin, China). A TA8120 digital luxmeter was purchased from Tasi Electronic Co. Ltd. (Suzhou, China). A MZ-2CNT diaphragm vacuum pump was from BRAND Trading Co. Ltd. (Shanghai, China) was used.

The compound preservatives were composed of epigallocatechin gallate (EGCG; purity ≥98%; Yuanye, Shanghai, China) lysozyme (LYS; ~70000 U/mg; Sigma–Aldrich, Shanghai, China). Gum tragacanth (GT) and sodium alginate (SA) were obtained from Aladdin, Shanghai, China. Glycerol, as a plasticizer for improving the flexibility of active coatings, was obtained from Macklin Biochemical Co, Ltd (Shanghai, China).