Wheat Wet Milling

FIGURE 8.4 Flowchart of the wet-milling Martin process for the prodnction of wheat starch and vital gluten. (Adapted from Knight, J.W., and Olson, R.M. 1984. Chapter 15 in Starch Chemistry and Technology, R.L. Whistler et al. (eds.). Second edition. Academic Press, Orlando, FL.) 

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Wet-milling is aimed towards the production of refined starches. It is mainly practiced to obtain maize starch, although wheat and rice starches are also processed. The aim of wet milling is to obtain prime starch for the further production of modified starches or sweeteners. The wheat wet-milling industry also obtains vital gluten that is used as an important additive in the production of bakery products and other foods including processed meats. 

Wheat wet milling is usually performed with two main objectives the production of vital gluten and the extraction of the starch (Figure 8.4). The European countries, the United States, Canada, Australia, and New Zealand channel important quantities of... 

Imported maize is the raw material for several food ingredients used in the bakery industry. While maize can be dry milled like wheat, it is more commonly wet milled. The wet milling process is much better suited to separating the different components of maize so that the oil, the protein and the starch can be recovered separately. Maize starch is used directly in bakery products as corn flour, so-called even in the UK. 

Wheat is normally dry milled. Maize can be dry milled but is normally wet milled. The wet milling process allows the maize to be fractionated into starch protein and oil. 

The vast majority of starch produced in the United States, either for sale as starch or for conversion to other products, is derived by the wet-milling of com. A small amount of starch is also produced by isolation from potatoes or extraction from wheat or rice flour. Current US companies involved in starch production are as follows. 

Although some initial successes were reported, the whole-wheat processes were shortlived, principally because the separation of fiber from gluten is difficult, and because drying of wet bran is energy-intensive. Batey84 opined that it seems unlikely that any wet-milling of wheat kernels will be economical, since only 6-7% of the kernels starch is lost in dry-milling. 

Com, tapioca, potato and wheat starches are the most commonly used starches in the US and Europe. In the US, 95% of the starch is made from corn, an amount representing 3.4% of the total com crop, excluding that wet-milled to make sweeteners (see Chapter 22) and alcohol11124 (see Chapter 2). In Europe, about 60% of the starch produced is made from com and about 20% each from potato and wheat.12 In select regions, rice, sorghum, arrowroot, sago and other starches are also used. The relative utility of these starches in foods is a function of differences in viscosity, stability to... 

Wheat Com fiber (from wet milling) 440-1800 Moreau etal., 1996,1999 Wu and Norton, 2000... 

This toxin is produced by several Fusarium spp., in particular by the scabby wheat fungus E graminearum (roseum) which also makes deoxynivalenol, DON [71]. It has an unusual macrocyclic sfructure [6(10-hydroxy-6-oxo-trans-l-undecenyl)-beta-resorcyclic acid-jr-lactone] (fig. 7). Zearalenone (also called F-2) is found in the gluten of contaminated wet-milled wheat, and also... 

Com-derived starch is a readily available feedstock in the U.S. It is produced efficiently in large quantities in com wet mills and provides the basis for much of the biomass-derived chemical production presently in the market The starch is enzymatically hydrolyzed on a large s e to produce glucose, much of which is isomerized to fhictose for use as food sweetener, and the rest mostly goes into ethanol production for automotive fuel. The several separation processing steps in the com wet mill are summarized in Figure I. Equivalent processing could be lied to wheat and potato or other starch when the feedstock is available at a suitably low price. 

Starch is produced in so-called refining industries in which aqueous streams are used to facilitate separation of the individual components present in the com and wheat kernels. The process is called wet-milling . 

Dried by-product from the manufacture of wheat starch by wet milling, containing about 25% starch (as fed) (n = 910). 

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