1. Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
2. Department of Food Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
3. Corresponding author. Phone: 204-474-6480. Fax: 204-474-7630. E-mail: scanlon@cc.umanitoba.ca