Wheat can be categorised according to the following parameters: sowing date, grain hardness, grain quality and flour grade.
Types of wheat
The following two types of wheat are by far the most widely grown in the growing areas:
Soft or common wheat (Triticum aestivum) is the most widely distributed type of wheat, also known as bread wheat. This species is generally characterised by its high protein and gluten content. The endosperm of the grain is either hard or soft.
Durum wheat (Triticum turgidum), or “pasta” groats, is known for its particular grain hardness, high protein content, rich yellow colour, pleasant smell, and excellent baking qualities. Between 25 and 30 million tonnes of durum wheat are produced annually, which is 4% of the total world wheat production.
Classification of wheat
Classification of wheat by sowing date
Common winter wheat
Typically, winter wheat is sown in September and harvested the following August (for the Northern Hemisphere). These varieties are considered unique due to their jarovisation requirements. Yarrowisation is a necessary requirement for the initiation of the flowering process, whereby the crop is exposed to prolonged low temperatures. It is an inherited trait that prevents the winter wheat floral meristem from developing too early and being damaged by cold. The response of plants to jarrowisation depends on two factors: the temperature of exposure and the duration of the jarrowisation period. Yarrowisation is completed when the plant meristem has reached the stage of the beginning of spring vegetation. There are three temperature ranges that are involved in the process of iarovitisation:
minimum, below which the process of jarovisation does not occur – usually temperatures between -1.3°C and -4°C;
the optimum, at which iarovisation is most effective – on average between 3 and 10°C, with a peak at 4.9°C;
the maximum, above which the yarrowing process stops – 15.7°C.
Studies show that there is a clear linear response of jarrowisation at temperatures between 0 and 8°C. It is generally accepted that for good quality winter wheat spring ripening it is necessary to be influenced by an optimum temperature for 50 days. This period is referred to as the effective days for saturation of the yarrowing reaction.
Common spring wheat
Unlike winter wheat, spring wheat does not require exposure to low temperatures (jarrowisation) to initiate flowering. Spring wheat is sown in January-February and harvesting begins in August. The growing season varies from 120 to 180 days depending on the climate. Exposure to temperatures between 7° and 18°C for 5 to 15 days is usually sufficient to trigger flowering of spring wheat varieties.
Wheat classification by grain hardness
The following is the classification of wheat according to the structure of the endosperm, which can be hard or soft:
Hard wheat is characterised by its high protein content. It is well suited for producing bread flour varieties. The starchy grains are hard and do not crumble during the milling process.
Soft wheat has a soft endosperm and the starch grains crumble well when milled. It is used for baguettes, biscuits and biscuits.
A dark-coloured, hard grain wheat rich in gluten. It is used for baking bread and making pasta. It is grown mainly in southern Russia, North Africa and north-central North America.
Classification of wheat by grain quality
Depending on the grain quality, the following groups of wheat can be distinguished:
These are durum wheat varieties with excellent milling and baking characteristics. The cost of flour from Group I grains will be higher than average, due to its fulfilment of quality requirements (13% protein content, Hagberg Falling Number (HFN) of 250 and specific gravity of 76 kg / hl).
This group contains a variety of wheat varieties, not all of which have potential for use in baking. Some varieties are not hard enough compared to Group I; others are too soft, while others are quite suitable for professional flour production.
This group contains soft wheat varieties ideal for the production of biscuit, pastry and other flours where the main requirements are soft milling characteristics, low protein content, good flour yield and a stretchable but not elastic gluten.
These wheat varieties are grown mainly as fodder wheat.
Classification of wheat by flour quality
Wheat from each group is used to make flour for the baking industry.
General purpose flour is the most widely used of all flours. This flour is made from the finely ground part of the wheat grain called the endosperm. General purpose flour is made from a combination of hard and soft wheat and is used for a variety of baked goods such as yeast dough breads, cakes, dry biscuits and muffins.
Bread flour is used for the industrial production of bakery products. Although similar to general purpose flour, bread flour has a higher gluten content.
Leavening flour is a type of general purpose flour to which salt and leavening agent have been added. It is usually used for biscuits and biscuits.
Pastry flour is a fine flour milled from soft wheat with a low protein content. It is used for making all types of baked goods such as: cakes, biscuits, crackers, etc. Pastry flour has a higher starch percentage and lower protein content than bread flour.
Semolina is the endosperm of coarsely milled durum wheat. Durum wheat is a hard wheat variety that is characterised by its high protein content. This makes it ideal for making high quality pasta and couscous.
Durum is a by-product of making semolina. It is usually a flour enriched with four B vitamins and iron and is used to make noodles.