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Enzymatic and bacterial conversions during sourdough fermentation
1University of Alberta, Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, Edmonton, Canada T6G 2P5.
Food Microbiology
|November 16, 2013
Summary
Bread quality relies on the interplay between flour components, cereal enzymes, and sourdough microbes. Lactic acid bacteria and enzymes work together, influencing carbohydrates, proteins, and more during fermentation.
Area of Science:
- Food Science
- Microbiology
- Biochemistry
Background:
- Bread quality is determined by the enzymatic and microbial conversion of flour components during bread making.
- Sourdough microbiota metabolism and cereal enzyme activity are interdependent, influencing each other's functions.
- Microbial metabolism, including acidification and thiol accumulation, modulates cereal enzyme activity, while enzymes provide substrates for bacterial growth.
Purpose of the Study:
- To review the roles of cereal enzymes and lactic acid bacteria metabolism in the conversion of carbohydrates, proteins, phenolic compounds, and lipids during sourdough fermentation.
- To highlight the interdependence between microbial metabolism and enzymatic activity in determining bread quality.
- To discuss the impact of specific substrates and compounds on microbial activity and selection.
Main Methods:
- Literature review focusing on enzymatic and microbial conversions in sourdough bread making.
- Analysis of the metabolic pathways of heterofermentative lactic acid bacteria in wheat and rye sourdoughs.
- Examination of the influence of cereal enzymes on substrate availability and microbial growth.
- Investigation of the roles of proteases, peptidases, and phenolic compounds in dough and bread.
Main Results:
- Heterofermentative lactic acid bacteria primarily metabolize sucrose and maltose, with maltose released by cereal enzymes.
- Sucrose metabolism by lactobacilli leads to acetate and exopolysaccharide formation, influenced by enzyme-released sugars.
- Proteolysis is driven by cereal proteases, while bacterial peptidase activity shapes peptide and amino acid profiles.
- Phenolic compounds in sorghum and millet influence microbial metabolism and select for resistant fermentation microbiota.
Conclusions:
- Cereal enzymes and lactic acid bacteria metabolism are crucial, interdependent factors in sourdough bread making.
- The conversion of carbohydrates, proteins, and phenolic compounds significantly impacts bread quality and characteristics.
- Understanding these interactions is key to optimizing sourdough fermentation for desired bread attributes.
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