Improvement of zein dough characteristics using dilute organic acids

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The dough functionality of the storage proteins in "gluten-free" grains has been studied for almost 25 years. Zein, maize prolamin, when isolated as α-zein can form a wheat gluten-like visco-elastic dough when mixed with water above its glass transition temperature. There is good evidence that its dough-forming properties are related to a change in protein conformation from α-helix to β-sheet and association of the molecules into fibrils. Stabilisation of β-sheet structure and visco-elasticity can be enhanced by inclusion of a co-protein. No other isolated cereal or pseudocereal storage protein has been shown to form a visco-elastic dough. Many treatments have been applied to improve "gluten-free" storage protein functionality, including acid/base, deamidation, cross-linking by oxidising agents and transglutaminase, proteolysis, disulphide bond reduction and high pressure treatment. Such treatments have some limited positive benefits on batter-type dough functionality, but none is universally effective and the effects seem to be dependent on the composition and structure of the particular storage protein. Research into mutants where prolamin synthesis is altered appears to be promising in terms of improved dough functionality and scientific understanding. Research into how treatments affect the functionality and structure of isolated storage proteins from "gluten-free" grains other than maize is required.2

Section: Dough Formationmentioning

confidence: 99%

Section: Influence Of Secondary Structure On Dough Functionalitymentioning

confidence: 99%

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Functionality of the storage proteins in gluten-free cereals and pseudocereals in dough systems

Taylor

Campanella

et al. 2016

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“…Nevertheless, the dough making properties of zein, the maize prolamin, can be considered because commercial zein (predominantly α-zein) forms a viscoelastic dough when hydrated above the glass transition temperature (T g ) of zein in water (~28ºC) (Lawton, 1992) and when mixed with starch or gluten-free flour can expand a bubble by Alveography (Sly et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Formation of a viscoelastic dough from isolated total zein (α-, β- and γ-zein) using a glacial acetic acid treatment

King

Taylor

2016

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Abbreviations: 2D-PAGE -Two dimensional polyacrylamide gel electrophoresis, CLSMConfocal laser scanning microscopy, FTIR -Fourier transform infrared spectroscopy, T gglass transition temperature 1 AbstractOnly predominantly α-type zein (commercial zein) has been shown to form a viscoelastic dough. In maize zein comprises α-, β-, γ-and δ-zein (total zein). Because glacial acetic acid can fully solubilise zein, its effect was investigated. Dissolving total zein (comprising α-, β-, γ-and δ-zein)_ in glacial acetic acid and casting a film, enabled a viscoelastic dough to be formed with water above zein's T g . The dough was stronger and less extensible than commercial zein dough made without film formation. When residual acetic acid was removed from the total zein film, a dough still formed.. CLSM showed that the total zein dough fibrils were shorter and less well-aligned than those of commercial zein dough and appeared as particles. Disulphide bond cross-linking was probably responsible, for total zein dough stiffness. FTIR showed that total zein wet doughs and total zein slurry with water were predominantly β-sheet, indicating that β-sheet conformation was not directly responsible for dough formation. It is suggested that acetic acid brings about chemical changes in zein, enabling it to better interact with water molecules, counteracting disulphide bonding effects, allowing total zein to form a dough. This is the first report of viscoelastic dough formation from total zein. 2

“…Although maize does not contain gluten, gluten-like functionality of zein (maize prolamin) dough as a result of acidification with lactic acid and acetic acid has been reported (Sly et al, 2014). The lactic acid bacteria fermentation process also acts on the other major structural component in dough, namely starch (Petrofsky and Hoseney, 1995).…”

Section: Introductionmentioning

confidence: 99%

Improvement of maize bread quality through modification of dough rheological properties by lactic acid bacteria fermentation

Falade

Emmambux

Buys

et al. 2014

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This work investigated how sourdough fermentation improves maize bread quality. Maize sourdoughs were made by fermenting maize flour with multiple strains starter culture and with Lactobacillus plantarum. Sourdough fermentation of maize dough brought about a 25-26% increase in loaf volume of maize bread. Confocal laser scanning microscopy revealed a cohesive dough structure in the sourdoughs. Larger cells were also observed in maize breads with maize sourdough. Differential scanning calorimetry showed that maize sourdough had a slightly lower endothermic peak temperature and higher endothermic peak enthalpy than straight maize dough. Rheological analysis showed that maize sourdoughs had a shorter relaxation time. Strain sweep analysis suggested that maize sourdoughs had the lowest elastic modulus, all indicating a softer and less elastic dough. Temperature sweep analysis showed an initial less elastic dough and a final high tan delta, suggesting that the maize dough could withstand gas expansion pressure during baking without crumbling. It appears that improvement in maize bread quality by sourdough fermentation is primarily due to starch granule modification which makes the dough more cohesive, soft and less elastic and improves its ability to trap and withstand the pressure of the expanding carbon dioxide during fermentation and baking.2