Flour of corn

Type

The various varieties of flours are labelisés according to the dry mass (mineral content) remaining obtained by incineration of a sample in a furnace of laboratory (generally with 550°C or 900°C).

There exist several types (symbolized by the letter T) according to their capacity in his and mineral:

T45 : white flour used for pastry making, the cakes,…
T55: white flour used for the bread known as of countryside .
T65: white flour which is used to make the farmhouse bread , or any other bread known as tradition , generally resulting from the Organic farming. The latter does not contain an Ascorbic acid (vitamin C) addition (contrary to T55 for example).
T80: flour semi-complete north wind or usually used in bakeries biological. Is used to make the semi-complete bread.
T110: whole-wheat flour. Is used to make the wholewheat bread.
T150: integral flour. Is used to make the integral bread.

The its is the envelope of corn. It is in the latter that one finds the residues of pesticides and other products used during the culture of corn, the flours of a type higher than T55 are thus often available - and advised - into biological to avoid any chemical residues in the flour.

Composition of the flour

Here, as example, the chemical composition of a flour of the type 55, flour most usually used for the manufacture of the Bread.

the Starch:

the starch is the principal element of the flour. Present in all cereals, it is a slow glucid which will be transformed by sugar carbonic gas the yeasts bakers then by the human organism during digestion. Impregnated water and heated with 70° C, the starch thickens: it is said that it forms a starch paste (example: the thickening of the sauce Bechamel sauce).

the Gluten:

the gluten is present in many cereals but its qualities are not as good as in corn. If the quantitative importance is relative, the role of the gluten has a very great importance in the manufacturing process of the bread or a fermented paste. It has properties of elasticity and extensibility: it thus will retain the pressure of carbonic gas (obtained thanks to the action of yeast) and thus will be stretched under this pressure, of course within a certain limit. One can compare the gluten with a small rubber balloon in which it is necessary to blow: at the beginning, resistance is important then, while resisting, it will be stretched. Arrived at its limits it will explode. It is by using these properties that one obtains the holes inside the crumb.

the Water:

It is also present in the flour. The law imposes on the Meunier an highest rate of 16%. Beyond, the flour would be difficult to preserve.

the Sugars:

They are very few in the flour. However they are directly fermentable and quickly comparable by the yeast which will transform them into

CO_2

(carbonic gas). They are composed of saccharose and glucose.

fat contents:

They are mainly in the germ and the envelopes. These two elements being removed with grinding, there remain very little in the flour about it. A too large quantity of fat contents would be harmful with the good conservation of the flour and would harm the role of the gluten.

mineral matters:

They are used to determine the quality and the purity of a flour like its type: 45 or 55 for example. The principal ones are the Phosphore, the Potassium, the Magnésium. The greatest part is located in the envelopes and the germ which, let us recall it, are removed by grinding.

the Vitamin S:

They are very few in the flour (the greatest part is in the germ). The Vitamine B1 takes part in the transformation of glucids, the Vitamine B2 supports the growth, the Vitamine PP is essential to the cells, the Vitamine E ensures the good performance of the nervous system and the muscles.

Technological criteria

Value miller : aptitude to give a good output in flour of purity wished with a minimum of energy.

Mass 1000 seeds such as they are. (*0.86 to have the weight of the dry grains)

real Volume 1000 seeds. Mesure with a picometer which one fills with hexane (water would be absorbed by seeds). Volume is measured before and after having added 1000 seeds.

Compactness

hardness . It is the collapsing resistance.

water content . The fundamental reference is to measure vacuum, with $P_2O_5$ during 60h with 50°C. But this method is very long and the industrialists prefer to take faster measurements.

If there is not enough water, it is necessary to humidify if not it will be difficult to take off the envelope of almond. If there is too much water, the seeds should be dried.

the rate of extraction . It is the percentage of the grain which gave flour. To carry out the extraction, one removes the envelopes which give the sound (one there finds many fibers) and the germ (which contains many lipids likely to oxidize). The more the extraction is pushed, the more the proportion of proteins, lipids, fibers, vitamins and minerals is high. Currently, the extraction is approximately 80%. For anecdote, it was of 98% at the time of the second world war. The flour then had very nutritional good qualities but of bad organoleptic qualities (taste).

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