Sourdough-isolated Lactobacillus fermentum as a potent anti-mould preservative of a traditional Iranian bread

Abstract

Sourdough bread is an ancient method for making long microbial shelf life and strongly flavoured breads. Traditional sourdough bread-making has been practised for centuries in Iran. Although rural bread-making is still highly reliant on sourdough, urban bakeries usually use baker’s yeast and also sodium bicarbonate instead. In this study the anti-mould preservative effects of three lactic acid bacteria isolates were investigated on one of the popular traditional Iranian bread (Lavash). Starter cultures were prepared using 20 h cultures of three sourdough-isolated strains, Lactobacillus casei, Lactobacillus plantarum and Lactobacillus fermentum. Different concentrations (0.5%, 1%, 2%, 4% and 8%) of lactobacillus starter cultures were used to prepare a variety of sourdoughs. Lavash doughs were inoculated with 20% of each lactobacilli-fermented sourdough. After a 20 h incubation at 30 °C, a decrease in pH was observed in the different lactobacilli sourdoughs. However an 8% inoculum of L. fermentum resulted in a significant decrease in pH (3.87 to 2.70). Concentrations of 2% and higher of the three lactobacilli used in Lavash sourdough delayed mould growth during storage. However this preservative effect was more significant when an 8% inoculum of L. fermentum was used. These results tend to suggest that selected strains of lactobacilli have a beneficial role in prevention of bread waste by mould spoilage, and hence could extend bread shelf life.