Influence of tyramine on bacterial growth and proteolysis in high milk protein model media.

摘要

High tyramine contents in fermented foods have been shown to contribute to suppression of growth of contaminating microflora; this effect is particularly evident in proteolytic microorganisms. Destruction of milk protein (in culture media containing 3.4% skimmed milk powder), by Serratia marcescens and Bacillus subtilis, was studied at room temp. for 36 h of cultivation in the presence of tyramine (0.25 mg/ml). Proteolysis decreased with increasing tyramine content, and test microbes diminished in broth or died after 24 h. Tyramine had a bacteriocin-like effect on proteolytic microbes and consequently a protective effect on milk protein. Suppressed bacterial growth was not connected with changes in pH, since pH levels of culture media almost always remained approx. neutral (6.5-7.5). Based on these results, the use of tyramine-tolerant starter cultures in inoculated food products was proposed.