1 Histidine decarboxylase-positive lactic acid bacteria strains and the formation of histamine in ripened cheeses Luis J. del Valle 1, Marta Ginovart 2, Elena Gordún 3, Rosa Carbó 3* 1 Departament d’Enginyeria Química, Centre de Biotecnologia Molecular (CEBIM), EEBE, Universitat Politècnica de Catalunya, Barcelona, Spain 2 Department of Mathematics, Universitat Politècnica de Catalunya, Barcelona, Spain 3 Department of Agri ‐ Food Engineering and Biotechnology, Universitat Politècnica de Catalunya, Barcelona, Spain Correspondence Rosa Carbó, Department of Agri‐Food Engineering and Biotechnology, Universitat Politècnica de Catalunya, Campus Baix Llobregrat, Esteve Terradas 8, 08860 Castelldefels, Barcelona, Spain. Email: rosa.carbo@upc.edu