AN-PEP Successfully Degrades Gluten in Rye Sourdough Products

Celiac.com 09/24/2018 - A team of researchers recently set out to investigate the degradation of gluten in rye sourdough products by means of a proline-specific peptidase.

The research team included Theresa Walter, Herbert Wieser, and Peter Koehler, with the Deutsche Forschungsanstalt für Lebensmittelchemie, Leibniz Institut in Freising, Germany.

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Their team monitored gluten content of rye sourdough during fermentation using competitive ELISA based on the R5 antibody. The team noted a decrease in gluten over time, but found that even prolonged fermentation did not bring gluten levels below 20 ppm requirement for gluten-free foods. 

Interestingly, they did find that Aspergillus niger prolyl endopeptidase (AN-PEP) extensively degraded gluten concentrations of up to 80,000 mg/kg in rye flour, rye sourdough, and sourdough starter under specific temperatures and pH values. Nor did the enzyme inactivate the microorganisms in the sourdough starter. 

Gluten-free rye flour alone or in combination with sourdough starter was used to produce gluten-free bread, which the team then assessed for its sensory characteristics. 

Whereas gluten-free sourdough bread lacked any of the favorable qualities of conventional rye bread, the replacement of sourdough by egg proteins yielded gluten-free bread comparable to the conventional rye, and with better qualities than bread made with naturally gluten-free ingredients. 

This study demonstrates the feasibility of using ANPEP treatment to produce high-quality gluten-free sourdough bread from originally gluten-containing cereals, such as rye. 

Rye products rendered gluten-free in this manner have the potential to increase the choice of high-quality foods for celiac patients. 

Source:

• European Food Research and TechnologyMarch 2015, Volume 240, Issue 3, pp 517–524