1. Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, P. R. China
2. Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, P. R. China
3. Laboratory of Risk Assessment for Quality and Safety of Bee Products, Ministry of Agriculture and Rural Affairs, Beijing 100093, P. R. China
4. Key Laboratory of Bee Products for Quality and Safety Control, Ministry of Agriculture and Rural Affairs, Beijing 100093, P. R. China