Reference Number: 609
Year: 2008
Link: Link to original paper
Health: Key Research Papers
Nutrition: Gluten
Yeast: Lactobacillus sanfranciscensis
Summary
Forty-six strains of sourdough lactic acid bacteria were screened for proteolytic activity and acidification rate in gluten-free (GF) flours. The sourdough cultures consisted of Lactobacillus sanfranciscensis LS40 and LS41 and Lactobacillus plantarum CF1 and were selected and used for the manufacture of GF bread. Fermentation occurred in two steps: (i) long-time fermentation (16 h) and (ii) fast fermentation (1.5 h) using the previous fermented sourdough as inoculum (ca. 43%, wt/wt) with Saccharomyces cerevisiae (baker’s yeast). GF bread started with baker’s yeast alone was used as the control.
Gluten was added to ingredients before fermentation to simulate contamination. Initial gluten concentration of 400 ppm was degraded to below 20 ppm only in the sourdough GF bread. Before baking, sourdough GF bread showed phytase activity ca. sixfold higher than that of GF bread started with baker’s yeast alone. Atomic absorption spectrophotometric analysis revealed that the higher phytase activity resulted in an increased availability of free Ca2, Zn2, and Mg2.
The concentration of free amino acids also was the highest in sourdough GF bread. Sourdough GF bread had a higher specific volume and was less firm than GF bread started with baker’s yeast alone. This study highlighted the use of selected sourdough cultures to eliminate risks of contamination by gluten and to enhance the nutritional properties of GF bread.
Significance of the study
Overall, the paper highlights the potential of sourdough fermentation to combat gluten contamination and increase the nutritiousness of gluten-free bread. Although the exploitation of sourdough in GF systems is still in its infancy, these results indicate that sourdough may be useful as a technological tool for preventing risks associated with gluten contamination and for improving the nutritional, texture, and flavour characteristics of GF bread.
