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Dextran-containing sourdoughs have been widely employed in baking, obtaining products with higher quality instead of adding additives. This study investigated effects of dextran of a high weight-average molecular weight (M w ) and linear structure, sourdough and their combination on wheat bread quality. The underlying mechanism was explored from properties of pasting, amylopectin retrogradation and water distributions of starch systems. Bread characteristic analyses showed that both dextran and weak acidification due to addition of sourdough improved bread quality, especially crumb softness. Dextran decreased moisture migration due to high water-binding capacity. Enhancements of amylose aggregation by weak acidification contributed to retardation of amylopectin recrystallization. A synergy existed between dextran and weak acidification. Dough rheology demonstrated that weak acidification was fundamental for dextran-induced positive dough viscoelasticity. This study indicates a combined anti-firming performance of high M w dextran and weak acidification, possibly being a promising strategy to prolong shelf life of wheat bread., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This research aimed at investigating the effects of different weight-average molecular weights (M w : T10, T70, T250, T750, T2000) of dextran (α-(1 → 6)-linked linear backbone, α-(1 → 3)-linked branching) on wheat sourdough bread qualities. Texture analyzer showed that dextran contributed to a significant inhibition of bread staling, particularly dextran T2000. Pasting profiles (Rapid visco-analysis) and steady rheological properties (steady shear measurements) of samples indicated that dextran T2000 suppressed the swelling and gelatinization of wheat starch granules and bound a great amount of water, thus retarding the aging process. Dextran T2000 markedly improved the elastic properties of sourdough-containing dough. Wheat sourdough breads containing dextran T10 exhibited unexpected less firm crumb structure. The improvement of bread qualities was a function of the M w of dextran. Dextran with high M w values has the potential for improving the quality of wheat sourdough breads, especially extending shelf life., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Reduced glutathione (GSH), released from lysed yeast cells, is well-known for weakening dough structure. However, its influence on bread texture and staling has not yet been completely elucidated. Herein, this study aims at assessing the effects of GSH on dough properties and bread quality, especially bread staling, using Rheofermentometer analysis, texture profile analysis (TPA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and low-field nuclear magnetic resonance (LF-NMR). The results revealed that GSH substantially decreased the dough height and gas-retention capacity during fermentation. The weakened dough structure was attributed to GSH-induced disulfide bond cleavage in gluten proteins and the depolymerization of glutenin polymers. The addition of 0.005%–0.01% GSH resulted in acceptable bread quality. However, bread supplemented with 0.015%–0.03% of GSH exhibited a coarser and more open crumb microstructure, as well as high level of hardness and low resilience during aging. GSH promoted crumb water loss and drove the water shift from the immobilized to the bound state. The DSC and XRD analyses further confirmed that GSH promoted starch retrogradation and recrystallization. These results suggest that apart from the gluten structure, GSH also altered gluten−starch interactions and water redistribution, ultimately decreasing bread quality and accelerating bread staling. Image 1 • Glutathione depolymerized protein and weakened gas retention capacity. • Glutathione decreased loaf volume and bread resilience, and increased hardness. • Moisture content decreased and water became less mobile with glutathione. • A coarser porous bread crumb was obtained in the presence of glutathione. • Bread staling rate was significantly increased in the presence of glutathione. [ABSTRACT FROM AUTHOR]

To improve the aroma of bread, two aroma-producing yeast isolates from the Chinese liquor starter culture called Daqu, Meyerozyma guilliermondii CGMCC 17606 and Pichia kudriavzevii CGMCC 17607, were combined with Lactobacillus sanfranciscensis DSM20451T, were used for sourdough fermentation at 10, 20, and 30 °C. Volatile aroma compounds in bread crumb were extracted using headspace solid-phase micro-extraction and analyzed using gas chromatography-mass spectrometry and gas chromatography-olfactometry-mass spectrometry. The quality of the final bread was analyzed using sensory evaluation. Addition of sourdough fermented with mixed starters at 10 °C promoted bread aroma, showed increased sensorial qualities, and was preferred by panelists. Acetic acid, 1-octen-3-one, and dimethyl trisulfide, were the most aroma-active compounds in sourdough bread fermented with M. guilliermondii and L. sanfranciscensis , whereas those in sourdough bread fermented with P. kudriavzevii and L. sanfranciscensis were acetic acid, 1-octen-3-one, 2-methoxy-4-vinylphenol, 3-methylthio-propanal, furfural, and 1-(2-furanyl)-ethanone. Reducing the fermentation temperature to 10 °C increased the formation of these key volatiles, as well as other aroma-active compounds, such as 3-methyl-1-butanol, 3-methylbutanal, 2-methyl-1-propanol, 1-octen-3-ol, isogeraniol, benzaldehyde, benzene acetaldehyde, ethyl octanoate, ethyl decanoate, phenylethyl acetate, furfural, and 2-pentylfurane. The amount of furans, pyrazines, and volatiles converted from amino acids in bread crumb also increased with the protein hydrolyzation and amino acid formation in sourdough fermented at 10 °C. Image 1 [ABSTRACT FROM AUTHOR]

Two yeast strains, Meyerozyma guilliermondii EH1 and Pichia kudriavzevii EP1, together with Lactobacillus sanfranciscensis DSM20451T were used as mixed starter cultures on sourdough bread making. Both yeast strains isolated from Chinese liquor Daqu were selected among 79 isolates by primary sensory evaluation of bread and growth test with L. sanfranciscensis during sourdough fermentation. High growth rate, resistance to acid and osmotic pressures were observed for both yeast strains. In presence of L. sanfranciscensis , M. guilliermondii EH1 and P. kudriavzevii EP1 exhibited higher growth rates and yields in wheat flour sourdough. Production of organic acids, specific loaf volume, crumb texture, crumb colour, staling rate, and volatile composition of the sourdough bread was evaluated. The results showed that the use of isolated yeast strains led to the higher accumulation of esters, aldehydes and other aroma compounds. Our findings demonstrated improved flavour complexity and increased consumer acceptance of bread using mixed starters. Image 1 • Meyerozyma guilliermondii EH1 and Pichia kudriavzevii EP1 were isolated from Chinese Daqu and applied on sourdough bread making. • The yeast isolates showed higher growth rates and yields with Lactobacillus sanfranciscensis during fermentation. • The physiochemical properties of sourdough bread made with mixed starters were evaluated. • Two yeast isolates had positive attributes to overall bread sensory quality. [ABSTRACT FROM AUTHOR]

Effect of pigskin-originated gelatin on dough properties and bread characteristics, especially on bread staling was investigated in terms of starch retrogradation and water migration in the present study. Results showed that gelatin significantly improved bread qualities during storage. Compared with the control, 7-day staling rate of bread containing 0.5% and 1.0% gelatin decreased by 6.56% and 20.83% respectively, indicating gelatin retarded the staling process of bread. This retardation effect was related to starch retrogradation and water migration. The relative crystallinity decreased from 15.12%, 11.60% to 10.75%, which demonstrated the alleviation effect of amylopectin crystallization. Bread samples containing 1.0% gelatin had the lowest retrogradation enthalpy of 2.93 ± 0.24 J/g followed by 0.5% gelatin bread and the control group, further indicating that gelatin may induce less water available to form crystal lattice and restrict the migration of starch molecules. The 5-day moisture loss rate for the control group was highest with the values of 12.39%, which was 1.43% and 1.83% higher than that of bread with 0.5% gelatin and 1.0% gelatin, respectively. Water activity and T 2 relaxation results provided the information that gelatin inhibited water migration upon storage and gelatin interacted with bread components. However, the effect of gelatin on improving bread quality and retarding staling could not be reflected by the dough properties measured through farinograph, extensograph and rheometer. This study suggested gelatin from pigskin had great potential to be served as an effective bread improver. Image 1 • Gelatin enhanced the bread qualities significantly, especially retarding the staling process. • Gelatin hindered the chain reassociation of starch molecules during storage. • Gelatin interacted with bread components and restricted water transfer. • Dough properties showed gelatin might to some extent weaken the gluten network. [ABSTRACT FROM AUTHOR]