Enhancement of Quality and Safety of Low-Salt Pixian Douban Fermentation with Paenibacillus polymyxa M17 27-6

Traditional <i>pixian</i> douban is characterized by elevated salt concentrations, often exceeding 12%. Given the established correlation between high-salt diets and various health disorders, the necessity for effective salinity reduction becomes evident. However, the reduction in salt content may result in quality deterioration. To address the adverse effects associated with decreased salt concentration, the strain <i>Paenibacillus polymyxa</i> M17 27-6, which possesses the capability to produce antimicrobial compounds, was used in the fermentation of low-salt <i>pixian</i> douban. Additionally, we employed low-salt uninoculated and high-salt uninoculated groups as fermentation controls, with the entire fermentation cycle lasting 35 d. In terms of safety, microbial diversity sequencing and the content of biogenic amines and aflatoxin B1 were conducted. Microbial diversity sequencing analyses indicated the presence of potentially pathogenic <i>Escherichia</i> and <i>Shigella</i>, as well as the spoilage-causing <i>Trichosporon</i> and <i>Issatchenkia</i>, in the uninoculated low-salt group, whereas no contaminating bacteria were detected in the inoculated group. Relative to the uninoculated low-salt group, levels of aflatoxin B1 and biogenic amines were significantly reduced. In terms of quality and volatiles, compared to the uninoculated high-salt group, concentrations of amino acid nitrogen and total acids increased to 0.93 g/100 g and 1.21 g/100 g, respectively, alongside significantly enhanced levels of organic acids and antioxidant activity. At the same time, volatile compound content and abundance increased. In conclusion, the incorporation of <i>P. polymyxa</i> M17 27-6 in the production of low-salt broad-bean paste effectively enhances quality and safety and provides a theoretical basis for developing low-salt <i>pixian</i> douban products.