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Protein Adhesives
Published in A. Pizzi, K. L. Mittal, Handbook of Adhesive Technology, 2017
Charles R. Frihart, Linda F. Lorenz
Although a lot of research has been done on separation of proteins using a variety of analytical techniques, the main evaluation of protein properties has been in dough mixing and property tests [61]. The ability of gluten to hold dough together indicates that these proteins may have some utility as an adhesive. Wheat flour contains 75%–85% starch and only 10%–15% proteins (wheat gluten) [61]. Therefore, the flour is of limited value as an adhesive unless there is a coreactant that decreases the water sensitivity of the starch. The natural occurrence is for the starch to be in granules and the protein more in the continuous phase. Although the protein is only a small part of the composition, being part of the continuous phase, it has a large impact on the physical properties of the dough.
Advances in Cereal Processing: An Approach for Energy and Water Conservation
Published in I. M. Mujtaba, R. Srinivasan, N. O. Elbashir, The Water–Food–Energy Nexus, 2017
P. Srinivasa Rao, Soumya Ranjan Purohit, Lakshmi E. Jayachandran
A GF diet is the only effective treatment for a fraction of the global population with celiac disease and gluten intolerance. The formulation of high-quality GF cereal-based products represents a challenging task for both the cereal technologist and bakers, especially due to the low baking quality of GF flours. Gluten is the major structure forming protein in the wheat flour and is responsible for the elastic nature of the dough. It also contributes to the appearance and crumb structure of many baked products. Several alternatives, such as starches, dairy products, gums and hydrocolloids, other nongluten proteins, prebiotics, and combinations thereof, are being used in place of gluten to improve the structure, mouthfeel, acceptability, and shelf life of GF bakery products. To overcome this issue, use of starches and gum/hydrocolloids is important in the development of GF cereal-based products to achieve desirable characteristics, such as high loaf volume, crumb softness, and appearance properties along with sensory acceptability (McCarthy et al., 2005). However, right selection and combination of hydrocolloids are crucial to obtain breads with a desirable quality. Replacement of 30% of wheat flour with rice flour results in bread with acceptable quality, whereas more than 30% of gluten substitutes are necessary. An optimized combination of hydroxypropyl methyl cellulose (HPMC) and CMC renders high-quality baked products similar to wheat bread. Different hydrocolloids like HPMC improve gas retention and water absorption, mimicking gluten characteristic. Similarly, xanthan gum imparts a good crumb structure in the absence of gluten, and CMC, agarose, or β-glucan promotes loaf volume (Dwivedi et al., 2014). Wheat and nonwheat starches (rice, potato, corn, cassava, buckwheat) can also be incorporated in the GF products for better quality baked products.
Three-Dimensional CFD Modeling of Continuous Industrial Baking Process
Published in Da-Wen Sun, Computational Fluid Dynamics in Food Processing, 2018
Weibiao Zhou, Nantawan Therdthai
In wheat flour-based products (bread, cracker, cookies, cake, etc.), dough is prepared through the formation of a wheat gluten network. When dough is subject to high temperature during baking, changes in its viscoelastic properties are found, depending on the physicochemical characteristics of the wheat gluten [36]. Heating at temperatures above 60°C leads to an increase in the storage modulus that characterizes elastic properties. This effect can be explained by the polymerization of glutenins as a result of a thiol-disulphide interchange reaction. The thermal effect induces the change from gluten gel to coagel [32]. A previous study [37] hypothesized that changes in the solubility of wheat gluten during baking were dependent on its gliadin fraction. Otherwise the changes might depend on the high temperature that allowed the activation of thermosetting reactions producing the intra- and intermolecular covalent bonds of a protein network. The change in the gluten phase also enhances the effects of starch gelatinization, such as the transformation from viscous dough into an elastic material [32]. After the protein is denatured during baking, water adsorbed in the gluten is released. Then starch uses this water for gelatinization [34,38]. Consequently, dough becomes semi-rigid bread. Before baking, water in the dough is estimated to be combined with starch (46%), protein (31%) and pentosan (23%) [39]. Immediately after baking, gelatinized starch granules are in an amorphous state. When bread is cooled down, water is redistributed as some starch turns to a crystalline state. More water from gluten is released to be incorporated into the crystalline structure of starch; as a result, staling is developed [40]. At this time, it is estimated that no water is associated with proteins. However, some water is still combined with pentosans due to their high hydration capacity [39].
Systematic assessment of wheat extenders in condensation resins for plywood production: Part I - physico-chemical adhesive properties
Published in The Journal of Adhesion, 2021
Elfriede M. Hogger, Hendrikus W. G. van Herwijnen, Johann Moser, Wolfgang Kantner, Johannes Konnerth
Wheat flour has been one of the most commonly used additives in plywood production for the past few decades,[3,9,10,13] making a closer examination of this issue of great interest. The main components of a wheat kernel are around 63–73% starch and about 12% protein.[14] A typical wheat flour composition consists of 67–70% starch and 12–18% protein.[15] Zeppenfeld and Grunwald[7] mentioned that starchy extenders exhibit filler properties within a resin below a temperature of 65°C and have a thickening effect due to the incipient gelatinization and binding of considerable amounts of water above this temperature. Dunky and Niemz[5] described how the protein content of flour can lead to a buffering of the acid curing reaction of aminoplastic resins.