Browsing by Subject "Anti-staling"

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Backmittel mit fermentativ angereicherten Hydrokolloiden
(2021) Seitter, Michael Friedrich Hermann; Hertel, Christian
Lactic acid bacteria (LAB) are involved in fermentation of sourdoughs and able to produce exopolysaccharides (EPS). Screening of 190 LAB of different species and genera showed that 82% are able to produce EPS. Whereby, 28% a strong or very strong production exhibited. It becomes evident that strains of species L. reuteri, L. sanfranciscensis, L. frumenti and L. pontis, could be identified as effective EPS producer. The molecular weight of the synthetized EPS was larger than 5*106 Dalton. Glucan was formed almost of L. reuteri strains. To identify the effect of commercial hydrocolloids on bread staling, baking trials were performed. The parameter crumb hardness using Texture-Profile-Analysis and retrogradation of starch using Differential Scanning Calorimetry were chosen. Staling of wheat breads was dependent on the flour quality. Breads produced using weak flours and straight dough method showed faster staling. Addition of isolated EPS produced by L. sanfranciscensis LTH 1729 (Glu/Fru ratio: 1:6) and LTH 2590 (Glu/Fru ratio: 1:45) was more effective in retarding the rate of staling compared to hydrocolloids guar gum and xanthan. Baking trials with chemical acidified sponges showed that swelling and endogenous enzyme activities exerts no positive effect on the rate of staling. In contrast to sponges with fermentative enriched EPS, which exhibits a delayed rate of staling. This effect could be verified in mixed wheat breads (rye : wheat, 50:50). Frozen storage of doughs revealed no influence on the rate of staling. Production of an EPS enriched dried sourdough (baking improver) using optimized fermentation conditions was performed using L. sanfranciscensis LTH 1729. 3% dosage of the baking improver showed similar staling rate compared to control, however with 2% higher water absorption. Thus, addition of hydrocolloids and EPS, respectively, leads to an increase in dough yield of 1 1.5%. The width-height ratio was comparable in all doughs, except the xanthan supplemented. After adjusting the doughs to 500 FE, all doughs showed similar results in measurements with Bohlin-Rheometer. Doughs with added hydrocolloids as well as EPS were less sticky. Fermented sponge doughs with enriched EPS showed higher stickiness compared to not enriched. This could be traced back to residual not metabolized amounts of sucrose. EPS addition affects extensibility of doughs less compared to gum guar and xanthan. Negative influence on dough structure using acidic sponges was compensated with EPS enriched ones. Addition of guar gum and xanthan effect in a viscosity increase during gelatinization. Whereas, EPS and EPS containing sponges showed no effect on viscosity. Frozen storage of 10 days reveals lower dough stability and gas retention. Doughs were less elastic and stickier. Dough resistance decreased and elasticity increased. By addition of EPS these effects could be compensated. The gas retention capability of EPS supplemented frozen doughs was identical not frozen ones. Addition of 3% baking improver produced by spray dried EPS enriched sourdough to doughs increased the water absorption by 2%, whereas almost no change on dough rheological parameters resulted. Dough stability and gas retention was considerably improved. Dough stickiness and resistance decreased. No effect in viscosity during gelatinization. Summarized, the results of the present work show the optimization and manufacturing of a “clean label” baking improver, produced thru EPS enriched fermentation of sourdoughs. As well as the application of the improver and the impact of on dough processing and fresh keeping of frozen dough and baked goods.