Effect of Sourdough Addition on Rheology of Whole Wheat and Gluten-Free Dough

Sourdough improves flavour, structure and nutritional value of baked goods and decreases the risk of gluten contamination in gluten-free bread. We investigated the effect of strain starter culture and the amount of added sourdough on whole wheat and gluten-free dough rheology. Wheat sourdough was fermented with Lactobacillus plantarum, Lactobacillus brevis or Leuconostoc mesenteroides mixed with Candida milleri in ratio 100:1 cfu/g, and gluten-free sourdough was fermented with Lactobacillus fermentum. Sourdough was added in bread dough at four levels: 7.5 ; 15 ; 22.5 or 30 %. We determined total titrable acidity, lactic and acetic acid concentration of sourdough, and bread dough rheology by texture analyser. Total acidity of sourdough samples was similar but acetic acid was significantly lower in Lb. plantarum sourdough. Wheat dough rheology was only affected by sourdough amount and did not differ between strains. In average, dough hardness, springiness and gumminess decreased by 46%, 17% and 45%, respectively, by adding 30% of sourdough. Similarly, dough rheology parameters negatively correlated to total acidity, lactic and acetic acid concentration in sourdough. In contrast, gluten-free bread dough rheology was less affected by sourdough addition. Springiness and gumminess of gluten-free dough decreased for 20% and 28% by adding 30% of sourdough. The results indicate that gluten-free dough tolerates much higher sourdough level than whole wheat dough.