Sourdough fermentation is obtained increasing interest especially in wheat baking due to several positive effects on bread quality and functionality. One of the interests is production of exopolysaccharides (EPS) by lactic acid bacteria during fermentation. High molecular weight water-soluble EPS act as hydrocolloids and contribute to the water distribution in dough, and further to softness and staling of bread whereas low molecular weight oligosaccharides may act as prebiotics. The most common EPS produced in sourdough fermentation are dextrans and fructans. We have lately identified a W. confusa strain, which efficiently builds dextran from the added sucrose in wheat sourdough without strong acid production. Dextran from W. confusa was found to be highly linear alpha-1,6-glucan with only very few alpha-1,3-branch linkages. A new specific enzyme-assisted method for in situ analysis of dextrans in sourdoughs was developed. With this method, we could for the first time proof significant production of polymeric dextran in sourdough. The method also enabled in situ evaluation of the type of dextran produced during the sourdough process. Concomitant formation of a series of shorter isomaltooligosaccharides during fermentation was also confirmed. Further detailed structural analysis by NMR spectroscopy of the isolated oligosaccharides released from dextran by enzyme hydrolysis gave invaluable detailed information on branch linkages in dextran.

In situ analysis of<i> </i>dextrans and isomaltooligosaccharides in wheat sourdoughs

239th National Meeting (2010)

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In situ analysis of dextrans and isomaltooligosaccharides in wheat sourdoughs