Wheat Flour Gluten Research Articles

Fun Microbiology

Breadmaking is one of humankind's oldest technologies, having been established some 5500 years ago by the Egyptians (Samuel 1996). Today, hundreds of different breads are produced by altering components and handling procedures (Gubser 1985; Hensperger 1999; Ojakangas 1998). Irrespective of type, bread is prepared with three basic ingredients: flour, yeast and water. Bread production is a science in which the balance of these basic ingredients is critical to the flavor and texture of the final product. The ability to produce naturally leavened bread with bakers' yeast (Saccliaromiiyces cerevisiae) depends largely on gluten which is found primarily in wheat flour. Gluten makes up the major protein component in flour: it is a tough, elastic, grayish substance that resembles chewing gum when wet (Shewry et al. 1995). It's the gluten in wheat flour that helps form the elastic network that is capable of trapping carbon dioxide gas (CO2) released by the yeast during anaerobic fermentation, giving rise to a firm spongy texture. The amount of gluten found in non-wheat flours (e.g. rye) is low, making nonwheat breads very dense or unleavened. Yeast cells also produce ethanol which evaporates during the baking process, and the yeast cells themselves impart a characteristic flavor to the bread (Prescott et al. 1999). [A summary of the yeast fermentation pathway is described in an earlier article (Mitchell 1995)]. Pretzels (and bagels) are unique among the breads in that the leavened doughs are placed into hot water (alkaline-water for pretzels) prior to baking (Hensperger 1999; Jakubek 1999). Traditional soft pretzel preparation (believed to have originated in Germany) calls for dough to be leavened twice before boiling. Lye or baking soda water is brought to a boil in a stainless steel or enamel container. Dough is lowered into the water, simmered 10 seconds on each side, removed, drained and baked (Kroskey 1996).

Effects of Temperature on Sorption of Water by Wheat Gluten Determined Using Deuterium Nuclear Magnetic Resonance

ABSTRACTThe effects of lipids and residual starch components of wheat flour gluten on gluten hydration properties were investigated using nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) techniques. Whole or native, lipid‐free, starch‐free, and lipid‐ and starch‐free gluten samples were prepared from wheat (Triticum aestivum) cv. Mercia. 2H NMR relaxation on gluten samples hydrated with deuterium oxide (D2O) was measured over a 278–363 K temperature range. FTIR spectra were recorded in dry and fully hydrated material. Transverse relaxation (T2) results indicated that all four gluten samples were hydrophilic in nature. There was little difference in relaxation behavior of whole and lipid‐free gluten samples. T2 values and populations of the relaxation components were very similar in each. The FTIR spectra of both samples showed an increase in extended β‐sheet secondary structures on hydration. These results suggest that lipid binding in gluten, if it occurs, has little effect on wheat gluten properties. Adding starch to the gluten matrix results in an increase in water sorption on heating that may be attributed to the effects of starch gelation. However, the whole water uptake of the gluten cannot be accounted for by the contribution of the residual starch, as estimated by the effects of added starch. Extraction of residual starch required solubilization of the protein, including breaking of the disulfide bonds. This process altered the gluten structure and properties. Light microscope investigation showed that glutens with residual starch extracted were unable to form fibrillar strands on hydration. NMR and FTIR results showed greater water sorption in both samples with extracted starch than in the unextracted samples.

Relationship between Baking Quality and Proportion of SDS-Insoluble Gluten in Wheat Flour.

The relationship between loaf volume and the proportion of SDS-insoluble gluten in wheat flour was studied using N-ethylmaleimide (NEMI) as a modifying reagent of gluten. The loaf volume responded to NEMI and was maximum at 10 ppm NEMI, but was minimum in the absence of yeast food. SDS-insoluble gluten had the same response to NEMI. Therefore, it was concluded that the loaf volume was positively related to the proportion of SDS-insoluble gluten. With excess NEMI (100 ppm), a substantial decrease in SDS-insoluble gluten was observed in the doughs. This was accompanied by a decrease in the relative viscosity of the ethanol-insoluble fraction (glutenin). This result suggested that excess NEMI caused a decrease in the molecular size of glutenin, probably by a thiol radical mechanism, leading to the decrease in SDS-insoluble gluten and then to deterioration of the baking quality of wheat flour. On the other hand, a lower amount of NEMI may determine the proportion of SDS-insoluble gluten and loaf volume.

Comparison of alginate and “Pesta” for formulation of Phanerochaete chrysosporium

Alginate and wheat gluten (“Pesta”) matrices were compared for the encapsulation of the white rot fungus Phanerochaete chrysosporium. “Pesta” granules were not successful for formulating P. chrysosporium although control granules made with Alternaria alternata yielded viable fungal colonies; the gluten in wheat flour apparently inhibits growth of the white rot fungus. P. chrysosporium formulated in alginate with corncob grits or sawdust, and stored at room temperature, yielded over 50% viability of encapsulated mycelia after six months. Alginate encapsulation offers a promising technology for the delivery of white rot fungi to toxic waste sites.