1. Department of Food Science and Human Nutrition, Iowa State University, 2312 Food Sciences Building, Ames, IA 50011.
2. Department of Botany, University of Hong Kong, Pokfulam Road, Hong Kong. Corresponding author. E-mail: hcorke@yahoo.com Fax: +852 2858 3477.
3. Department of Food Science, University of Pretoria, Pretoria 0002, South Africa.
4. Cereal Quality Laboratory, Department of Soil and Crop Science, Texas A&M University, College Station, TX 77843.