Description
Millers produce combinations of wheat flours to fit the baking market as needed. To provide quality flours for their buyers, mills use measures of moisture and protein content, weight, cultivar, hardiness, and other grain characteristics. These properties determine the milling quality of grain:
1. Moisture content: Wheat quality is threatened when the moisture content of stored grain exceeds 15%.There is a risk of infestation and mould as well as mycotoxin formation,all of which can lead to rejection.
2. Specific weight: Thin, shrivelled grain will not mill to produce adequate amounts of clean, white flour. The specific weight test measures the weight of grain – in kilograms – that can be packed into a cylinder of fixed volume, normally 1 litre, and indicates grain filling.
3. Screenings and admixture: Screenings are undersized grains and admixture comprises impurities, eg. chaff, weed seeds and earth, which must be removed before milling marketable flour. Screenings and admixture represent a loss to the miller, so a maximum of 2% is normally allowed. Screenings and admixture are measured using standard slotted 3.5 mm and 2 mm sieves.
4. Variety: Wheat varieties are categorised by nabim Groups 1 to 4. Groups 1 and 2 are used for most breadmaking, while Group 3 is used for a range of biscuit, cake and batter flours.
5. Protein content: Protein content is specified for all bakery flours and is a key part of the contract. For most breadmaking flour, wheat with a protein content above 13% dry matter, is preferred . If protein content cannot be achieved using homegrown wheat, imported high protein wheat or wheat gluten can be added in. For most biscuits and cakes, gluten formation is not required and much lower protein flours may be used .
6. Protein quality: When wetted, during dough making, some of the proteins in wheat flour form a visco-elastic substance – gluten. This can hold gas produced during fermentation and supports the starch and bran producing a typical well-risen UK loaf. The amount and quality of gluten produced indicates potential performance. No fixed threshold exists.
Read More: http://www.hgca.com/publications/documents/varieties/milling_wheat.pdf