College of Food Science and Technology Henan University of Technology Zhengzhou 450001 China;
College of Food Science and Technology Henan University of Technology Zhengzhou 450001 China;
College of Food Science and Technology Henan University of Technology Zhengzhou 450001 China;
College of Food Science and Technology Henan University of Technology Zhengzhou 450001 China;
Sorghum; Tannin; Ferric ammonium citrate assay; Optimization;