A fermented meat model system for studies of microbial aroma formation

A fermented meat model system was developed, by which microbial formation of volatiles could be examined. The model was evaluated against dry, fermented sausages with respect to microbial growth, pH and volatile profiles. Fast and slowly acidified sausages and models were produced using the starter cultures Pediococcus pentosaceus and Staphylococcus xylosus. Volatiles were collected and analysed by dynamic headspace sampling and GC-MS. The analysis was primarily focused on volatiles arising from amino acid degradation and a total of 24 compounds, of which 19 were quantified, were used for multivariate data analysis. Growth of lactic acid bacteria was comparable for model and sausages, whereas survival of S. xylosus was better in the model. Multivariate analysis of volatiles showed that differences between fast and slowly acidified samples were identical for model and sausage. For both sausage and model, fast-acidified samples had a high content of ketones, sulphides and methyl-branched acids, whereas slowly acidified samples had the highest content of methyl-branched alcohols, aldehydes, their ethyl esters, phenylacetaldehyde and methional. Furthermore, model repeatability with respect to pH, microbial growth and volatile profiles was similar to sausage production. Based on these findings, the model system was considered valid for studies of aroma formation of meat cultures for fermented sausage.