Produção de materiais de referência para avaliação de métodos microbiológicos em alimentos: estafilococos coagulase positiva e Listeria spp. em leite em pó

The quality of assays performed at food microbiology laboratories is an important factor with regard to international trade of products and ensuring food safety in order to avoid risk to consumers’ health. We emphasize the importance of conducting studies on the production of reference materials (RM) for proficiency testing in this area. The aim of this study was to produce and evaluate the quality of two RM lots containing Staphylococcus aureus and Listeria innocua in milk by freeze-drying technique with sucrose as a cryoprotector agent. The RM was considered homogeneous and stable at temperature -70°C for approximately eight months. It was concluded that the use of sucrose and freeze-drying technique were satisfactory for the MR production.