The Effects of Starter Cultures on Biogenic Amine and Free Amino Acid Contents in Nham during Fermentation

Abstract

Fermented pork sausage, or Nham, is a Thai-style fermented food which relies mainly on adventitious microorganisms, normally found in raw materials. The fermented foods usually contain biogenic amines produced by the microorganisms which caused the reaction of amino acids decarboxylation. These compounds are associated with toxicological symptoms. The objective of this study was to study the influence of two decarboxylase negative starter cultures in the presence of biogenic amines and free amino acid contents in Nham. Derivative biogenic amines by dansyl chloride were determined by high performance liquid chromatography (HPLC). Cadaverine and tyramine were determined during ripening process. The highest concentrations of biogenic amines were found at the end of the ripening process in the control sausage with no starter culture. Starter cultures test showed that Lactobacillus sakei BCC102 and Debaryomyces hansenii BCC 106 were efficient in reducing the amine production since these strains caused a quick pH drop during sausage fermentation. Total free amino acids after fermentation process decreased and the high decreases in the contents were glutamine and arginine while tyrosine and lysine, precursors for tyramine and cadaverine, respectively, increased in all batches. This study suggested that the use of decarboxylase negative lactic acid bacteria as starter cultures, which produced a rapid decrease on the pH of the meat mixture, was important factor to be considered to reduce the levels of biogenic amines in Nham.