The effects of pH on tyramine production in fermented sausages

Three types of fermented sausages were produced using the same sausage batt er but with pH adjusted to 3 different levels: (A) natural pH of sausage ba tter 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 Lac tobacillus acidophilus, or not inoculated. The results showed that as the p H of both inoculated and uninoculated fermented sausages was lower, tyramin e content in the finished product was higher. This phenomenon cannot be exp lained only by differences in viable counts of the tyramine-producing organ isms, as tyramine contents and final bacterial numbers were uncorrelated in most cases. Rather, it can be attributed tu the enhancing effects of low p H on either the tyrosine decarboxylase productivity of these organisms, or on the enzyme activity itself, or on both.