Effects of addition of probiotic bacteria on biogenic amines content in fermented milk during fermentation and storage

This study aimed to investigate the formation of biogenic amines (BAs) during fermentation and storage in fermented milk. The traditional culture was used as a control, and three different probiotics were added to the above culture as different experimental groups. Results revealed that the degree of protein hydrolysis in fermented milk increased during fermentation but decreased during storage, reaching a maximum value (14.8%–17.3%) at the end of fermentation. The trend of total amino acid content and total BAs content were similar to those of the degree of hydrolysis. The total amino acid content reached a maximum value (2.83–3.22   mg/mL) after 24   h of post-ripening. Fermented milk had the highest tyramine content, but it was always below 10   mg/L. The total BAs content in fermented milk during fermentation and storage ranged from 9.04 to 15.2   mg/L and 6.37 to 14.0   mg/L, respectively. These levels consistently remained below the threshold considered harmful to humans. The pH reduction rate, the total bacterial cell number, the degree of hydrolysis, and the total amino acid content in fermented milk all affected the formation and content of BAs. This study provides a foundation for assessing potential public health impact of BAs in fermented milk.