1. Department of Food Science, The Queen's University of Belfast, Belfast BT9 5PX, U.K., Department of Agriculture for Northern Ireland, Newforge Lane, Belfast BT9 5PX, U.K., Teagasc, The National Food Centre, Dunsinea, Castleknock, Dublin 15, Ireland, and Istituto di Scienza e Tecnologia degli Alimenti, Facoltà di Medicina Veterinaria, Università di Parma, via del Taglio 8, 43100 Parma, Italy