Dough viscosity

The position of the pot or pan in the oven could be determined and heat distribution adapted. Dough rounders with better control of many functions could be developed, including the determination of dough viscosity, humidity, color, particle size and some constituents. 

Food processors are exploring the application of many other enzymes which will have equal or greater impact than chymosin. For example, proteases have been used in baking for control of dough viscosity. An example is the production of crackers as shown in Figure 1. 

Reduction of dough viscosity more pliable dough... 

Kneaders, Z- and sigma-blade, and Banbury mixers as shown in Figure 7.20, are generally used for the mixing of high-viscosity liquids, pastes, rubbers, doughs, and so on. The tanks are usually mounted horizontally and two impellers are often used. The impellers... 

Pan mixers Vertical, rotating paddles, often with planetary motion Mixing, whipping and kneading of materials ranging from low viscosity pastes to stiff doughs Food, pharmaceuticals and chemicals, printing inks and ceramics... 

Enzymic actions that depolymerise proteins such as the high molecular weight glutenins will cause the viscosity of the dough to drop. This outcome is predictable on the basis of polymer science. 

Rye Proteins. While rye is the only European cereal able to completely replace wheat in bread, rye protein is not as effective as wheat protein. One reason for this is that as much as 80% of the protein in a rye sour dough is soluble compared with 10% of soluble protein in a wheat dough. One factor that inhibits the formation of a gluten-like complex is the 4-7% of pentosans present, which bind water and raise the viscosity of the dough. The crumb structure is then formed from the pentosans in combination with the starch. 

While the Dove composition described in Table 9.4-2 was processable at reasonable line speeds on a conventional soap processing line (roll mills, extruders, stampers), some equipment modifications were necessary. For example, whereas soap is normally mixed in large agitated tanks, the Dove mixture had a much greater viscosity and therefore required use of a steam-jacketed kneader mixer such as those used to make bread dough, pastes or mastics. 

Oxidation also results in starch depolymerization, which is the cause of the low viscosity and improved clarity and stability exhibited by oxidized starches. Oxidized starches are used in foods as coating and sealing agents in confectionary, as an emulsifier and as a dough conditioner for bread, whereas bleached starches are used for improved adhesion of batter and breading mixes in fried foods. 

The final web thickness of flake and tubular powders, after the removal of solvent, amounts to 53-65% of the web thickness of the strip at the moment of extrusion. The extent of shrinkage depends on such factors as total solubility, the viscosity of nitrocellulose, the quantity of solvent and the composition of the dough at the moment of extrusion. A greater solubility and a higher content of solvent lead to greater shrinkage of the strip. 

Figure H3.1.9 The characterization of the baking of a cookie dough by the measurement of the complex viscosity (r, solid line) as a function of temperature (°C, dashed line).

There are numerous examples where food extensional properties are relevant from the product quality perspective - some obvious examples include the extensibility of doughs, stretching of Mozzarella or Pizza cheese melts, extrusion-cooking of cereals, flow of honey and treacle. Overall, dough products have received the most attention. The importance of extensional viscosity in food processing has been reviewed by Escher (44 and references therein). 

These results highlight the genuine need for carrying out steady state experiments for accurate measurement of dough extensional viscosity. At the present time, there is no other instrument available that can provide stress-growth profiles for doughs. 

K. Mani, A. Eliasson, P. Dejmek and C. Tragardh, The Viscosity of Wheat Flour Doughs - the Problem of Slip, Anal. Trans. Nordic Rheol. Soc., 2 35-37 (1994). 

M. Padmanabhan and M. Bhattacharya, Planar Extensional Viscosity of Corn Meal Dough, J. Food Eng., 18 389-414 (1993). 

Both polymeric and some biological reactors often contain non-Newtonian liquids in which viscosity is a function of shear rate. Basically, three types of non-Newtonian liquids are encountered power-law fluids, which consist of pseudoplastic and dilatant fluids viscoplastic (Bingham plastic) fluids and viscoelastic fluids with time-dependent viscosity. Viscoelastic fluids are encountered in bread dough and fluids containing long-chain polymers such as polyamide and polyacrylonitrite that exhibit coelastic flow behavior. These... 

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