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Flour from soft wheat is low in protein and yields flour having low water absorption capacity and poor tolerance to mixing and fermentation. They are undesirable for bread production but are highly desirable in production of cakes, pastries and cookies.
Good flour is creamy white powder with a faint, pleasant smell, a slightly sweet taste, and when squeezed firmly in the hands, should tend to cling together and easily fall apart. When mixed with approximately half its own weight of water it forms a plastic mass known as dough. The composition of flour can vary considerably, depending upon the different types and sources of wheat used.
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Flour constituents
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Suitability of flours
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Soft and semi-sweet hard doughs(%)
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Fermented doughs (%)
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Starch
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74.50
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71.50
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Moisture
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14.00
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13.50
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Proteins- gluten forming
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7.00
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10.00
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Proteins-soluble
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1.00
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1.00
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Sugar
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2.00
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2.50
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Fat
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1.00
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1.00
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Ash (mineral salts)
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0.50
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0.50
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Starch consists of microscopic cells, insoluble in water but absorbs water during storage. When heated in water the starch cells absorb water and swell, prolonged boiling bursts the cell walls forming gel when cooled.
Proteins are soluble in water and coagulate on heating. An excess of soluble proteins is detrimental to fermented dough’s. The insoluble proteins or gluten forming proteins are most important. Gluten the structure forming component not only varies in quantity, but also in quality; it can be soft and elastic, or tough and rubbery.
Moisture varies from 11 to 15 per cent, depending upon storage conditions and the hygroscopic nature of the starch. Moisture content more than 14 per cent poses microbial contamination.
Sugars in flour are chiefly sucrose and maltose both of which although in only small quantities are important as yeast food for fermented doughs.
Fat in the wheat grain is concentrated in the germ and in the bran, and so a high fat content denotes low grade white flour.
Ash or mineral consist of phosphates of calcium, magnesium, and potassium, with traces of iron and aluminum. Additives increase the value.
Fiber indicate the traces of fiber or cellulose, lower values indicate higher refinement.
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