1. Dept. of Agricultural, Food and Nutritional Science Univ. of Alberta Edmonton Alberta Canada T6G 2P5
2. Biological Systems Engineering Dept Washington State Univ P.O Box 646120 Pullman Wash 99164‐6120 U.S.A
3. College of Food Science South China Agricultural Univ Tianhe, Guangzhou 510642 P. R. China