1. Phytonutrients Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville Maryland 20705; Chemistry Research Unit, CMAVE, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida 32608; Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, Pennsylvania 19038; and Agronomy Department, University of Florida, Gainesville, Florida 32611