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Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra-red (FTIR) spectroscopy, thermogravimetric analysis, and water uptake. The reaction between gluten and citric acid was examined for gluten : citric acid ratios of 0.38 : 1 to 0.75 : 1 at temperatures from 100 to 130 C. More citric acid reacted for samples containing higher citric acid concentrations and at higher temperatures. FTIR analyses indicated the presence of carboxylate groups on the modified gluten samples, which resulted in modified samples having higher water uptake values than neat gluten. The sample with a gluten:citric acid ratio of 0.5 : 1 and reaction temperature of 120 C had the largest water uptake value. Also, all modified gluten samples had lower thermal stability than neat gluten.

Cereal Chem. 83(2): [136][137][138][139][140][141][142] Wheat flour and water mixtures at 90% absorption (dry flour basis) prepared at various mixing times were examined using Fourier transform infrared (FT-IR) reflectance spectroscopy. Spectra were obtained using a horizontal attenuated total reflection (ATR) trough plate. The apparent amount of protein and starch on the surface of the dough varied with mixing time but this was likely due to the polyphasic nature of the substrate and the changing particle distributions as the batter matrix was , Wheat flour dough or batter may appear to be uniform and well mixed but actually it is multiphasic: starch, gluten, lipids, and water representing the principal phases. Furthermore, the form of these phases changes during periods of mixing that prepare them for separation or food uses. Microscopic changes begin with the instant formation of protein fibrils at first contact of water and flour particles (Bernardin and Kasarda I 973a,b; Amend and Belitz 1991). Slow mechanical development induces these fibrils to coalesce into fibrous bands or tendons and segregates the starch into clusters. When flooded with a displacing fluid, this open, sponge-like structure readily releases the entrained starch. This unmixed or separable state is evident in dough at 56-65% absorption and in batter at 90% absorption (Tipples and Kilborn 1975;Robertson and Cao 1998;Robertson et al 2000). Additional development disbands the protein into relatively line, uniformly distributed, and networked or webbed filaments that entrap the starch and gas bubbles formed when the dough is fermented and baked.The physical properties of hydrated wheat proteins are the result of covalent and noncovalent interactions of wheat gluten proteins. These interactions are altered by the repeated extension, tearing, and compression during mixing or development. Specific chemical effects include 1) disulfide bond disruption, 2) chain disentanglement and rupture, 3) disulfide-sulfhydryl interchange, 4) formation of dityrosine cross-links, 5) formation of new disulphide cross-links, 6) free radical interactions, and especially 6) reorientation leading to enhanced hydrogen bonding (Golstein 1957;