1. Shaanxi Natural Carbohydrate Resource Engineering Research Center College of Food Science and TechnologyNorthwest University Xi'an 710069 P. R.China
2. Key Laboratory of Applied Surface and Colloid Chemistry Ministry of Education and School of Chemistry and Chemical EngineeringShaanxi Normal University Xi'an 710062 P. R. China
3. Department of ChemistryUniversity of Liverpool Liverpool L69 7ZD UK