BA such as histamine and tyramine, a BA for longtime neglected in food research, can be found in fermented milk and meat products due to microbial decarboxylation activities. However, the identification of responsible MO, the regulation of tyrosine decarboxylation and dependence from food intrinsic factors, tyramine concentrations in these foods, tyramine and total BA exposure of consumers and the toxicity itself are not clearly identified which would facilitate EFSA and Swiss authorities to define limit concentrations for BA in food. The final objective of this project is to generate knowledge to be applied for tyramine reduction in Swiss cheese and fermented meat. The specific objectives are
A) to identify dominant tyramine producing MO in fermented food from Swiss market or directly producers with high tyramine concentrations such as different cheeses and fermented salami-type meat and to verify or neglect the hypothesis that Enterococcus spp. are the relevant tyramine producers in cheese or whether other MO contribute to the tyramine production in cheese and fermented sausages.
B) to characterize mechanisms of tyramine production in responsible dominant MO, with Enterococcus isolates as model MO, also under food processing and storage conditions leading to high tyramine contents
C) to search for lactic acid bacteria supplying tyramine-degrading capacity, elucidation of the mechanisms, especially tyramine catabolic proteins
D) to deliver a synthesis of our data and data from others which enable Swiss Food Safety authorities to propose measures and recommendations for tyramine reduction or even concentration limits in food
