Optimization of exopolysaccharide yields in sourdoughs fermented by lactobacilli |
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Authors: | Susanne Kaditzky Rudi F Vogel |
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Affiliation: | 1.Technische Mikrobiologie,Technische Universit?t München,Freising,Germany |
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Abstract: | In this study, the yields of exopolysaccharides (EPS) produced in situ during sourdough fermentations with Lactobacillus reuteri TMW 1.106 synthesizing glucan from sucrose were investigated under variation of the fermentation parameters dough yield (DY),
pH, sucrose content and fermentation substrate. The obtained amounts of EPS after 1 day of fermentation were higher in softer
(DY 500) than in firmer (DY 220) doughs. With the regulation of the pH to a constant value of 4.7, the optimum for EPS synthesis
in liquid medium, the EPS production in dough also increased. The EPS yield could further be improved by additional sucrose
fed-batch during fermentation. Fermentations with wheat flours, a rye-wheat mixture and rye bran with 10% sucrose as fermentation
substrate showed, that the use of rye bran is a promising tool to get high dextran formation through L. reuteri even in the first 8 h of fermentation. Further, alternative production of oligosaccharides and organic acids from sucrose
was investigated. Lactobacillus reuteri synthesized high amounts of acetic acid leading to low fermentation quotient values. In wheat doughs, the formation of maltooligosaccharides
was observed. Confirmatory experiments with fructan producing Lactobacillus sanfranciscensis TMW 1.392 revealed the same trends with a few distinct differences, indicating that this approach is transferable to other
EPS types and producers. |
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Keywords: | Lactobacillus reuteri Lactobacillus sanfranciscensis Exopolysaccharides Sourdough In situ production |
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