Organic Acids and Bacterial Communities of Backslopped Sourdough Prepared with Japanese Pear (Pyrus pyrifolia Nakai) Infusion

Addition of fruit during sourdough preparation can lead to the development of distinctive bacterial communities and fermentation characteristics. However, sourdough preparation with Japanese pear infusion remains understudied. We prepared sourdough with Japanese pear infusion and evaluated its organic acid composition and bacterial community. Sourdough was passaged for up to 56 generations. pH decreased rapidly during the initial generations of backslopping and subsequently stabilized at 3.5 and 3.7. High-performance liquid chromatography analysis revealed that lactic and acetic acid were the major organic acids. The fermentation quotient in the 55th and 56th generations ranged from 0.64 to 0.70, indicating an acetic acid-dominant profile. Bacterial community analysis targeting the V3–V4 region of the 16S rDNA gene revealed Furfurilactobacillus rossiae and Acetobacter pasteurianus as the dominant taxa. Average nucleotide identity analysis identified the representative isolates as Furfurilactobacillus milii and Acetobacter pasteurianus subsp. pasteurianus, respectively. This descriptive study is limited by a small sample size, lack of a control group, initial bacterial community data, and limited statistical analysis. Nevertheless, under the experimental conditions of this study, relatively high acetic acid levels were observed in the analyzed sourdoughs, together with a bacterial community dominated by the genera Furfurilactobacillus and Acetobacter were observed as predominant genera.