Wheat is an annual grass belonging to the Poaceae (Gramineae) family, tribe Triticae (Zohary, 2000). The wheats currently cultivated are the diploid T. monococcum (Einkorn wheat; 2n = 14, genetically described as AA plants), the tetraploids T. dicoccum (emmer wheat) and T. durum (pasta wheat or hard wheat) (2n = 28, genetically described as AABB plants), and the hexaploids T. aestivum (soft wheat or bread wheat) and T. spelta (spelt) (2n = 42, genetically described as AABBDD plants).
Currently, about 95 % of the wheat grown worldwide is bread wheat, with most of the remaining 5 % being pasta wheat. The latter is more adapted to the dry Mediterranean climate than bread wheat. Small amounts of other wheat species (einkorn, emmer, spelt) are still grown in some regions including Spain, Turkey, the Balkans and the Indian subcontinent.
In Italy, these hulled wheats are together called farro (Szabó and Hammer, 1995), while spelt continues to be grown in Europe, particularly in Alpine areas (Fossati and Ingold, 2001). Table 1.2 Wheat production estimates in the 10 leading producing countries; fi ve-year average 2006–2010 Rank Country Production (Mt) Area harvested (Mha)
Average of wheat yield among the 10 leading-producing countries. Source: Data from FAO/UN (2012). Wheat and other Triticum grains 5 © Woodhead Publishing Limited, 2013 Wheat for the purpose of trading is classifi ed into distinct categories according to grain hardness (soft, medium-hard and hard) and colour (red, white and amber).
It may be further subdivided into subclasses based on growing habit (spring or winter). Each wheat subclass may also be grouped into grades, which are generally used to adjust the basic price of a wheat stock by applying premiums or penalties. Wheat grades are indicators of the purity of a wheat class or subclass, the effects of external factors on grain soundness (rain, heat, frost, insect and mould damage) and the cleanliness (dockage and foreign material) of the wheat lot.
Today, wheat is a major component of most diets of the world because of its high agronomic adaptability, nutritional quality, the fact that it can be stored effectively indefi nitely before consumption (provided the water content is below about 15 % dry weight and pests are controlled) and the ability of its fl