Fermentation technologies for improved nutritional quality and digestibility of wheat products

AWC contribution: $70,000

Principal Investigator: Dr. Michael Gänzle, University of Alberta  

Start date: March 1, 2018

End date: September 30, 2021

Summary: 

The use of sourdough in industrial baking reduces ingredient cost, achieves “clean label” solutions by replacement of additives, and the quality of bread. Fermentations are carried out at the bakery or by specialized ingredient suppliers. Sourdough also has the potential to degrade immune reactive proteins during fermentation. This project aims to develop fermentation technologies to reduce levels of adverse components in wheat and to improve tolerance of wheat products.

 Objective:

Sourdough fermentation allows the selective elimination of fructans and reduced flatulence and abdominal pain in irritable bowel syndrome patients without decreasing the overall fibre content of rye bread. The selective degradation of rye fructans is achieved by use of a specific sourdough containing fructan degrading lactobacilli. However, polysaccharide degradation in homo-fermentative lactobacilli is glucose-repressed and it remains thus unclear whether a comparable degradation of wheat fructans can be achieved in wheat sourdoughs. The use of sourdough fermentation to decrease gluten proteins or allergens is well documented, however, the fate of trypsin-amylase inhibitors or wheat agglutinins during sourdough fermentation remains unknown. This project aims to develop fermentation technologies to provide novel avenues in improving the tolerance of wheat products.

Benefits to industry:

Up to 30% of North American consumers avoid wheat consumption owing to manifest celiac disease (1%), gluten intolerance (6%), because they are family members of celiacs or individuals with gluten intolerance, or because of self-diagnosed gluten intolerance (Agriculture and Agri-Food Canada, 2014). Accordingly, gluten free food products have been the most significant contributor to growth in the functional food market in Canada and abroad, and gluten free products have gained significant shelf space and market share. This wheat avoidance increasingly impacts the production of wheat for use in food, which is particularly relevant for Canada’s Prairie Provinces. Moreover, food processors are challenged to develop wheat- and gluten free food products that meets consumer’s expectations.
 
Fermentation with lactic acid bacteria provides solutions for reduction of wheat components that are known or suspected to contribute to gluten intolerance. Fazer Inc. commercialized a low-FODMAP bread in Finland that is produced with lactic acid bacteria expressing extracellular glycosyl hydrolases. Moreover, lactic fermentation of wheat is known to extensively degrade water soluble proteins in wheat, including allergens that are recalcitrant to proteolytic degradation. While lactic fermentation has not directly been shown to reduce noxious wheat proteins, preliminary evidence suggests that bread produced with lactic acid bacteria is tolerated by gluten- sensitive individuals.
 
Sourdough biotechnology is a rapidly growing segment in the market for baking improvers, and is the most significant contributor to innovation by the baking industry. However, economical benefits of large-scale production of sourdough bread or sourdough-based baking improvers are almost exclusively realized outside of Canada. This project will contribute to the development of “Made in Canada” solutions for novel fermentation technologies, and will train two highly qualified personnel for employment by Alberta’s baking industry.

Findings:

Results demonstrate that a conventional sourdough fermentation reduces the levels of fructans, the major FODMAPs in wheat and rye, during bread-making to a level that likely improves the tolerance of wheat and rye bread even by sensitive individuals. The use of a strain of Lactobacillus crispatus that expresses an extracellular enzyme degrading fructans allowed to reduce wheat and rye fructans by more than 90%.

The fate of immune-active proteins in wheat sourdoughs and wheat bread was assessed by quantification with LC-MS/MS (ATI) or enzyme-linked immune-sorbent assays (WGA). Sourdough fermentation decreased the level of both proteins; for ATI, the reduction was mainly attributable to acidification of the sourdough; for WGA, the effect was attributed to thiol-exchange reactions. Both proteins denatured during baking, however, and differences between sourdough bread and control bread produced with baker’s yeast only were not detected.

Overall, this project makes an important contribution to understanding the impact of sourdough fermentation on wheat constituents that are known or suggested to contribute to non-celiac wheat intolerance. Project results informed communication strategies of the wheat industry to restore the confidence of consumers in the wholesomeness of wheat and wheat products and thus maintaining both its market share and farmers’ flexibility to include wheat in their cropping systems.

Bio:

Dr. Michael Gänzle is a professor and Canada Research Chair in Food Microbiology and Probiotics. His current research projects focus on the functional characterization of lactic acid bacteria for use as starter cultures, protective cultures, or probiotics in food with a focus on cereal-associated lactic acid bacteria; production of oligosaccharides from sucrose or lactose by lactic acid bacteria and biological activities of oligosaccharides; novel, non-thermal preservation methods with a focus on high pressure processing and bio preservation; and intestinal microbial ecology with focus on the use of prebiotic carbohydrates and dietary fibre to improve host health.