Abstract
ABSTRACTFactors influencing tyramine formation and the presence of tyrosine decarboxylase activity in natural microflora and starter (Pediococcus cerevisiae) fermented sausages were determined. Maximal levels of tyrosine decarboxylase were found during the period of rapid acid development in the natural microflora fermentations. Higher levels of decarboxylase were present in the natural fermented sausages compared to the starter fermented sausages. Tyrosine decarboxylase activity increased during the drying treatment in the natural microflora sausages but remained low in the starter fermented sausages. Greater tyramine contents were found in the natural microflora sausages which had free L‐tyrosine added prior to fermentation. Tyramine contents of the natural microflora and starter fermented sausages without added L‐tyrosine generally reached similar tyramine levels. In the starter fermented sausages, tyramine and tyrosine decarboxylase development comparable to the amounts found in natural microflora fermented sausages occurred only in a sausage which contained added L‐tyrosine that was inoculated with a tyrosine decarboxylase positive Streptococcus faecalis. The study indicated that the natural meat microflora developed during the aging of salted meat can develop tyrosine decarboxylase activity necessary for rapid conversion of tyrosine to tyramine. The use of a starter culture such as P. cerevisiae appears to decrease the possibility of development of a microflora during fermentation that would possess both tyrosine decarboxylase activity and proteolytic activity necessary to produce fermented sausages with potentially hazardous tyramine concentration.
Published Version
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