Assessment of antifungal activity of aqueous extracts and protein fractions from sourdough fermented by Lactiplantibacillus plantarum

In the search for sustainable alternatives to preserve food safety, the characterization of organic acids, peptides, and antifungal protein fractions from lactic acid bacteria fermentations emerges as a promising strategy. This study analyzes the antifungal capacity of organic acids and protein fractions derived from sourdough fermented with Lactiplantibacillus plantarum NRRL B-4496. During the heterofermentative fermentation of the wheat dough, lactic acid (189.17 mM) and acetic acid (36.78 mM) were mainly formed. Four protein fractions were obtained and tested; fraction A (MW > 10 kDa) presented the highest amount of protein, followed by fraction B (MW > 30 kDa). These fractions demonstrated strong antifungal capacity. Aqueous extracts and protein fractions inhibited the evaluated fungi (>90 %); their neutralization and hydrolysis caused a considerable decrease in antifungal activity, evidencing the direct relationship between organic acids and protein fractions. Proteinaceous compounds >30 kDa showed strong antifungal activity, while fractions (MW < 30 or < 10 kDa) showed weak activity. These findings suggest that protein species, as well as organic acids derived from sourdough fermentations with Lactiplantibacillus plantarum, could be promising natural antifungal agents for food applications, contributing to the reduction of synthetic preservatives and the promotion of sustainable practices in food production.