1. Department of Food Science and Technology, University of California Davis, 1 Shields Avenue, Davis, California 95616; NSF Center of Biophotonics Science and Technology, University of California Davis, 2700 Stockton Blvd., Suite 1400, Sacramento, California 95817; Department of Chemistry, University of California Davis, 1 Shields Avenue, Davis, California 95616; and Nestle Research Center, Lausanne, Switzerland