Effect of exogenous DPD on fermentation characteristics and flavour formation of Lactiplantibacillus plantarum HRB1 in vitro and in a dry sausage model: Insights from the quorum sensing system

The present study aimed to investigate the impact of 4,5-dihydroxy-2,3-pentanedione (DPD; 0, 300, 600, and 900 nmol/L), a crucial precursor in the LuxS/AI-2 quorum sensing system, on flavour formation by Lactiplantibacillus plantarum HRB1 both in vitro and dry-sausage model. Firstly, L. plantarum HRB1 was selected from 18 strains of lactic acid bacteria due to its superior AI-2 and protease activity. In vitro, DPD significantly increased the activity of the AI-2 and the protease activity of L. plantarum HRB1. In the fermented dry-sausage, free amino acid content was significantly higher in the treatment with 600 nmol/L DPD compared to the other treatments. Notably, the dry sausage treated with 600 nmol/L DPD exhibited the highest concentrations of aldehydes (558.50 μg/kg), ketones (192.41 μg/kg), alcohols (1175.56 μg/kg), acids (202.27 μg/kg), esters (1504.48 μg/kg), and terpenes (1319.82 μg/kg). Sensory analysis revealed that the dry sausage treated with 600 nmol/L DPD had the most pronounced fermented and fatty odour. These results suggest that 600 nmol/L DPD enhances the flavour formation of L. plantarum HRB1. This research provides a theoretical foundation for utilizing the LuxS/AI-2 QS to optimize microbial fermentation processes and improve fermented food quality, especially flavour.