Inhibitory mechanism of tyramine-degrading strains on reducing tyramine accumulation in Harbin dry sausage during fermentation

To reduce tyramine accumulation in Harbin dry sausage, two tyramine-degrading strains, Lactobacillus sakei and Staphylococcus epidermidis, were inoculated in Harbin dry sausage. Changes in pH, aw, protein degradation, microbial growth, and tyramine content during fermentation were determined. The results showed that two strains could increase the abundance of corresponding genera and form population dominance in the early fermentation stage. Particularly, L. sakei could significantly reduce the pH and aw of Harbin dry sausage (P < 0.05) and promote the degradation of myosin heavy chain and actin. The alpha-amino group content was increased due to L. sakei, which resulted in an increase in tyramine content in the early fermentation stage. After fermentation, the tyramine content in the compound fermentation group decreased to 31.91 mg/kg, which was 55% less than that in the spontaneous fermentation group (70.21 mg/kg). Therefore, co-inoculation with tyramine-degrading strains could reduce tyramine accumulation in Harbin dry sausage.