Effect and mechanism of ferulic acid inclusion complexes on tyramine production by Enterobacter hormaechei MW386398 in smoked horsemeat sausages

Ferulic acid inclusion complexes (FA-HP-β-CD) effects on tyramine accumulation and gene expression of Enterobacter hormaechei MW386398 in traditional smoked horsemeat sausages were studied. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to identify the expression of tyrosine decarboxylase (TDC) clusters in the tyramine producing pathway. In addition, relevant parameters such as microbial growth , moisture content, pH, and tyramine accumulation in pure cultures and during fermentation of smoked horsemeat sausages were evaluated. Ferulic acid (FA) and FA-HP-β-CD inclusion complexes both significantly decreased tyramine accumulation, as well as significantly inhibited tyrosine decarboxylase (tdcA) and tyrosine/tyramine antiporter (tyrP) genes expression ( p  < 0.05). Furthermore, FA and FA-HP-β-CD inclusion complexes both reduced the number of Enterobacteriaceae in smoked horsemeat sausages, but did not alter the main microbiota . However, FA-HP-β-CD inclusion complexes exhibited stronger ability in hindering TDC related gene expression, reducing tyramine accumulation and antibacterial properties . These results indicate that FA-HP-β-CD inclusion complexes are able to reduce tyramine accumulation in smoked horsemeat sausages by inhibiting Enterobacteriaceae growth and gene expression.