1. Dept.Agricultural Eng., Michigan State University, East Lansing, MI 48824-1323.
2. Corresponding author. E-mail: steffe@egr.msu.edu Phone: 517/353-4544. Fax: 517/353-8982.
3. Dept. Food Sci. and Human Nutrition, Michigan State Univ., East Lansing 48824-1323.