Grits maize

There is an extensive array of adjuncts nsed for brewing and distilled alcohol production. The most relevant sources are maize and rice grits, maize starch, and barley. In some breweries or distilleries, liquid adjuncts consisting of different types of syrups (i.e., glucose, invert, maltose) are also nsed. The preferred adjnncts are carefully controlled in terms of physical and chemical properties discnssed in Tables 15.2 and 15.3. The grannlation or particle-size distribntion is critically important because it affects lautering or filtration rate. On the other hand, the adjnnct color contributes... 

Adjunct Common name of a starchy raw material mixed with diastatic malt during mashing processes for beer or alcoholic spirit production. Most adjuncts are refined fractions or starches obtained from dry- and wet-milling processes. The most widely used adjuncts are refined maize and rice grits, maize starch, ground barley, and syrups. Upon hydrolysis, adjuncts provide fermentable carbohydrates and soluble peptides, the key ingredients for the fermenting yeast. 

Cereal flour, including maize flour, maize grits and maize meal Cereal flour, except maize flour 750 75... 

Maize flour, maize grits and refined maize oil -... 

Meuser, F., Wittig, J., and Huster, H. 1989. Effects of high pressure disintegration of steeped maize grits on the release of starch granules from the protein matrix. Starch/Stdrke 41, 225-232. 

The machinery has been borrowed from the plastics industry. An early single screw extruder was used in the 1940s to produce a snack product from maize grits but the operational advantage of twin screw machines was demonstrated later. It appears that they are more efficient in mass transport, less heat is dissipated, and therefore heat transfer can be better regulated by barrel heating (Lo et al. 1998). 

Richmond and Smith examined maize grits and showed extremely nonlinear increases of pressure and temperature along the barrel. Within the first two-thirds of the barrel length, the grits are hydrated, mixed and compacted, and pressures remain low. After compaction, pressures and temperature rise rapidly to 100°C and >40 psi and result in a transformation to a starch continuum with embedded granules whieh... 

Figure 18.1. Structural change in maize grits. (From Richmond and Smith 1987, with permission.)...

Guy and Home reported qualitatively similar behaviour for maize grits and wheat flour. They also identified a transition zone, where particles become deformable, so that air is excluded and a eontinuous mass is formed. They noted that wheat starch granules lose bitefringenee but remain visible at this point. Further shearing resulted in granule breakdown and the formation of a system continuous in exposed starch polymers, and entrained partieles of other matter, sueh as protein and fibre. 

Table 18.1. Extrusion cooking of maize grits showing variation in SME input and mass temperature in shear zone with moisture eontent.

Unfortunately, there is little comparable detail on starch behaviour under extruder conditions, at low moisture. The previously cited scanning microscopy shows that at moisture contents of 25%, the SME imparted by the extruder is sufficient to form a starch continuum in most systems, and extrudates formed from maize grits extruded at 28% moisture 160°C and a die pressure of only 1 Mpa show homogenous polymeric cell walls (Donald et al. 1993). 

Figure 18.5. Specific volume and moisture content for maize grits extruded at 300 rpm, feed rate 800 g/min through O, 3 or , 4 mm dies. (From Guy and Home 1988, with permission.)...

The expansion at the die is not the sole determinant of final product specific volume. Guy and Horne (1998) also report the extent of shrinkage on cooling of extruded maize grits (Figure 18.7). 

Senouci and Smith (1988) used a simplified analysis for converging flow in a piston-driving capillary rheometer at 120-130°C and obtained ratios of uniaxial extensional viscosities to shear viscosities of maize grits and potato powder in the range of 60-3900. 

Shelled grain Maize flour Maize grits... 

Dry-millers process maize in two ways by stone grinding the kernels to produce hominy grits and full-fat whole meals, and by the tempering-degerming or TD process (Figure 7.3). The latter process is the one most commonly practiced by the industry and produces highly refined grits, meals, and flours with extended shelf life. 

Fine grits 50 to 75 Used as brewing adjuncts, raw material for production of maize... 

Corn flakes is still the most popular breakfast cereal in the world. Dr. Kellogg developed the traditional process at the beginning of the twentieth century. One hundred years later, this breakfast cereal is still manufactured following the same basic steps detailed in Figure 11.2. The process starts with careful raw material selection. Grits from yellow maize are preferred because of their stronger flavor and rich golden... 

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