1. Department of Crop Science, Box 7629, North Carolina State University, Raleigh, North Carolina 27695-7629; Department of Biological and Agricultural Engineering, Box 7625, North Carolin State University, Raleigh, North Carolina 27695-7625; and Market Quality and Handling Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Box 7624, North Carolina State University, Raleigh, North Carolina 27695-7624