Flour starch damage

Figure 8.1.1 shows that the first point of NIR analysis in a typical mill is for the testing of wheat at intake. This was the first application of NIR in the flour milling industry. In addition, automated systems based on whole-grain NIR are available for the control of wheat blending. The next opportunity for a control system would be in the reduction system. Here, an NIR measurement of flour starch damage would provide the opportunity (not yet realized) to implement a feedback control of the... 

Figure 8.1.6. Plot of Megazyme versus NIR flour starch damage.

B. G. Osborne. Improved NIR prediction of flour starch damage. In Proceedings of Australian Cereal Chemistry Conference, L. O Brien, A. B. Blakeney, A. S. Ross, C. W. Wrigley, eds. RACI, Melbourne, 1998, p. 434—438. 

B. G. Osborne, T. Feam, J. Blakeney. On line monitoring of flour starch damage by NIR. QWCRC Report No. 16, Quality Wheat Cooperative Research Centre, North Ryde, NSW 2113, Australia, 1998. 

FIGURE 19.4 Plot of Megazyme vs. NIR flour starch damage. 

It should be appreciated that a high level of starch damage is not essential in bread. French bread is made from soft wheat flour with a low starch damage. Starch damage is generally undesirable in biscuits. In biscuits the product is cooked to a very low moisture content so binding in water is undesirable. 

It is not particularly easy to measure the degree of starch damage present. The usual method involves treating the flour with a-amylase, which can only attack the damaged starch. The procedure requires an a-amylase preparation that has to be standardised. Alternatively, an estimate can be made by optical microscopy or by calculating from the water absorption of the flour and its protein content, assuming that the water absorption that exceeds that to be expected from the protein alone is due to the damaged starch. 

Some bread flour mills have difficulty in making a low starch damage soft wheat flour, a job that the mill was not intended for. This is probably why some millers do not make biscuit flours, leaving them as a niche product for the smaller milling companies. 

Wafer Flour. Wafer flour is a type of biscuit flour with the same basic specification of low protein soft wheat flour with a low starch damage. Once again the required dough property is extensibility. The only differences are that if the protein is too low the wafer will be too soft to handle, and if the protein is too high the wafer will be too hard. The other important property is a resistance to gluten separation. Wafer flours are likely to be brown. 

Once any directly fermentable sugars have been used up the yeast can only be fed by sugars produced from the starch. The only starch that can be broken down is the damaged starch. This explains why a certain amount of starch damage and some amylase activity is desirable in a bread flour. 

In a flour mill the Farinograph is used as a control instrument since the water absorption of flour can be increased or reduced by adjusting the mill, to deliver more or less starch damage. If the water absorption is too low, the pressure on the reduction rollers of the mill will be increased, thereby increasing the starch damage. Similarly, if the water absorption and hence the starch damage is too high the pressure must be... 

All of these loaves will have been made from French soft wheat flour without the use of fat or soy flour. This flour will have been milled with a low starch damage from varieties of French soft wheat grown for bead making. 

The demand for authentic French bread is obviously a sign of greater cosmopolitanism fuelled by increased foreign travel. The commonest. British attempts at an authentic French loaf are made from flour milled in Britain using French wheat. The requirement to mill with a very low starch damage is not achievable in some British bread flour mills. 

The preference for low protein, low starch damage flour in biscuits is obvious when the role of protein and damaged starch as water binders is considered. The aim in making biscuits is to produce a low moisture food. Incorporating components that bind water makes that aim more difficult. Table 2 considers the relative properties of biscuit and bread flours. 

Research using sets of Australian and New Zealand commercial flour samples augmented with samples produced on a 650 kg/h pilot mill resulted in a calibration with an =. 940 and SECV = 0.41 % (Figure 19.4) [ 15]. In this study, the improvement to the accuracy of starch damage calibration depended on a more precise reference method than that used previously the use of a research monochromator instrument (NIRSystems Model 5000) and its associated software (specifically. Modified Partial Least Squares regression) and careful control of sample temperature. In particular. 

It must be concluded that NIR is not applicable to the prediction of flour baking quality and is of limited use for measurement of ash. However, it may be used on a routine basis for measurement of protein, moisture, starch damage, water absorption, particle size, and color. 

Hatcher, D.W. Edwards, N.M., and Dexter, J.E. 2008. Effect of particle size and starch damage of flour and alkaline reagent on yellow alkaline noodle characteristics. Cereal Chem. 

Starch damage due to faulty storage or sprouting can be determined via hydrolysis with a-amylase or indirectly determined by a measurement of the viscosity of a slurry prepared from the ground grain or flour. The lower the viscosity, the greater the starch damage. 

Reduction system Name of the milling rolls used after break rolls in wheat milling operations. The reduction rolls are smooth and usually rotate at a differential speed of 1.5 1 or less. These rolls gradually reduce the particle size of middlings into flour, minimizing starch damage. Most mills contain from 8 to 12 reduction roll units. 

Damaged starch is also more readily degraded by enzymes. The ability to absorb water is the most important property of damaged starch since it adds to the ability of flour to absorb water. If all the starch in a flour is undamaged then only the protein will absorb water. 

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