The effects of pH on tyramine production in fermented sausages

Abstract

Three types of fermented sausages were produced using the same sausage batter but with pH adjusted to 3 different levels: (A) natural pH of sausage batter was nor altered, (B) pH was artificially decreased by adding GDL and (C) pH was artificially increased by adding sodium bicarbonate. Each type of sausage batter was either inoculated with tyramine-producing strain of Lactobacillus acidophilus, or not inoculated. The results showed that as the pH of both inoculated and uninoculated fermented sausages was lower, tyramine content in the finished product was higher. This phenomenon cannot be explained only by differences in viable counts of the tyramine-producing organisms, as tyramine contents and final bacterial numbers were uncorrelated in most cases. Rather, it can be attributed tu the enhancing effects of low pH on either the tyrosine decarboxylase productivity of these organisms, or on the enzyme activity itself, or on both.