Wheat or Wheat

Soft wheat and durum wheat

See also: wheat starch, wheat muscle; wheat germ

In nature there are different types of wheat; the most used are two: the Triticum durum (or durum wheat) and the Triticum vulgare (or soft wheat). Although the two plants are very similar on a structural level, they are not simply two different varieties, but two distinct species (durum wheat has 28 chromosomes, while the soft one has 42).

Durum wheat is used to make semolina, which is used to make dry industrial pasta (it is not by chance that the words "semolina pasta") and some types of bread (such as Altamura) are printed on the package.

By law, the term flour must be applied exclusively to the product obtained from the milling of soft wheat; with semolina, instead, we mean the product of grinding durum wheat. For other flours, such as corn, it is necessary to specify the origin on the label (cornmeal, oatmeal, etc.).

Structure of the caryopsis

The wheat fruit, called caryopsis, is entirely covered by a fibrous pericarp; it is an outer shell, consisting of multiple layers of cells rich in cellulose and mineral salts; this part, after the milling process, constitutes the bran.

Below the pericarp there is a monocellular layer, consisting of large cells of cubic shape; this portion is called the aleuronic layer and separates the heart of the caryopsis from the external integuments. From a nutritional point of view, the pericarp is particularly rich in nutrients, such as proteins, lipids, vitamins and mineral salts; however it is particularly small in quantitative terms and, above all, it is lost during the milling process. On one side of the caryopsis we then find the germ or embryo, the portion that gives rise to the new plant when sown in the ground; this part is also removed during the milling process, as it is particularly rich in proteins and especially lipids (the famous wheat germ oil is widely used in the dietetic and cosmetic sector). Most of the caryopsis is occupied by the amylar endosperm or albumen, a reserve fabric rich in starch and protein granules. It is from this portion that flour and semolina for food use are made.

Nutritional values

It can vary in relation to different factors, such as the variety of wheat, the climate, the cultivation techniques (conventional, organic, etc.), the type of soil on which it is grown and the nitrogen inputs (fertilization).

WATER (8 - 18%)

GLUCIDES (72%), of which:

AMIDO (60 - 68%)

PENTOSANS (6.5%), polymers of non-fermentable aldopentoses

CELLULOSE AND LIGNIN (2 - 2.5%) localized in the outer layers and therefore absent in white flour

REDUCING SUGARS (1.5%) (dextrins and glucose that derive from starch demolition processes; this is a small but extremely important percentage, because it is used by yeast as a nourishment to operate the metabolic process that leads to leavening of the dough).

PROTEINS (7-18%): based on their solubility in water they are divided into four classes, common to all types of cereals (albeit in different ratios):

ALBUMINE (9%): they are found mainly in the aleuronic layer and in the germ, both removed during the milling process (they are therefore absent in the traditional flour); these are high biological value proteins, especially rich in lysine, proline, leucine and glutamine.

GLOBULINE (5-7%): they are found in the germ, which is however removed (also from wholemeal flour) because it is rich in lipids and as such subject to rancidity; they also have a high biological value and are rich in lysine, arginine, serine and cysteine.

GLUTELINE and PROLAMINE (75 - 95%): abound in the amylar endosperm; in wheat, glutelins are called glutenins, while prolamines are called gliadins. Although abundant from a quantitative point of view, they are scarce in terms of quality, as they are rich in cysteine, proline and glycine, but poor in lysine and methionine, which represent the limiting amino acids of cereals. This requires the combination with protein foods, such as cheese, meat, eggs or legumes (which have an "incomplete" amino acid composition, but complementary to that of cereals).

The glutelins and the wheat prolamines are very important from the technological point of view, since when the flour is hydrated and kneaded they interact with each other forming a three-dimensional lattice called gluten.

LIPIDS: they are located mainly in the germ and include triglycerides (rich in unsaturated fatty acids, which represent 80 to 84% of the acidic fraction) and small amounts of phospholipids, glycolipids and sterols (sitosterol and campesterol).

MINERAL SALTS (1.5 - 2%): localized above all in the external integuments, therefore in the pericarp, they include phosphates of magnesium and potassium, salts of calcium, iron, copper and zinc

VITAMINS: B vitamins (in the aleuronic layer) and vitamin E (more abundant in the germ).

Anti-nutritional factors: phytic acid, abounds in the pericarp and chelates the bivalent metals (calcium, iron, copper, magnesium and zinc) reducing their absorption.

COMPOSITION OF WHEAT CARIOSSIDE AND ITS ANATOMICAL REGIONS (average values - g / 100g of dry matter)
Anatomical region of the wheat caryopsis	Percentage of the caryopsis	Starch and other carbohydrates (%)	Protein (%)	Lipids (%)	Cellulose hemicellulose Pentosani (%)	Mineral substances (%)
teguments	9.0	14.0	12.8	2.4	65.2	5.6
Aleuronic layer	8.0	12.0	32.0	8.0	38.0	10.0
Germ	3.0	20.0	38.0	15.0	22.0	5.0
endosperm	80.0	83.0	11.0	3.0	2.0	1.0