Development of a reference material for Staphylococcus aureus enterotoxin A in cheese: Feasibility study, processing, homogeneity and stability assessment

Staphylococcal food poisoning is caused by ingestion of enterotoxins which are excreted into foods by some strains of coagulase positive staphylococci, mainly Staphylococcus aureus. To protect consumers, Commission Regulation 1441/2007 specifies thresholds for the presence of these toxins in foods such as cheeses. In addition, the reference method to be applied for detection is defined (extraction, dialysis concentration, immunochemical toxin detection). In order to enforce legislation, it is indispensable to have suitable quality assurance tools such as reference materials (RMs) available to implement and safeguard reliable measurements. Anses and IRMM collaborate to develop a RM for Staphylococcal enterotoxin A (SEA) in cheese. First a feasibility study was conducted to establish a suitable processing procedure for producing large quantities of homogeneous and stable cheese powders. Three types of materials were made, and the following one proved to be most suitable: the blank material was prepared by cutting, grinding, freeze-drying, milling and mixing. For the spiked material, the cheese was converted into a slurry, spiked with a solution of SEA, freeze-dried, mixed, and diluted with blank material to the target SEA concentration level. Thereafter, large batches of three materials (blank, very low contaminated, low contaminated) were processed, and the materials' homogeneity and short-term stability were assessed using the reference method. The materials showed to be sufficiently homogeneous for the intended used, and storage at +18 ºC for 4 weeks did not indicate any detectable material degradation. These results provide the basis for the development of a RM for SEA in cheese.

ZELENY Reinhard;  EMTEBORG Hakan;  CHAROUD-GOT Jean;  SCHIMMEL Heinz;  NIA Yacine;  MUTEL Isabelle;  OSTYN Annick;  HERBIN S;  HENNEKINNE Jacques-Antoine; 

2014-09-23

ELSEVIER SCI LTD

JRC88997

0308-8146,   

http://www.sciencedirect.com/science/article/pii/S0308814614011042,    https://publications.jrc.ec.europa.eu/repository/handle/JRC88997,   

10.1016/j.foodchem.2014.07.066,