Wheat

Botanical Profile

Triticum aestivum is bread wheat and one of the world's most important cereal species. From a raw-material perspective, grain, flour, bran, germ, germ oil, grass, starch, gluten and fermented products must be clearly distinguished.

Triticum aestivum L. is an annual cultivated grass of the Poaceae. The plant forms hollow culms, linear leaves, terminal ears and grains that are botanically caryopses. Bread wheat is hexaploid and the result of complex domestication and hybridisation processes within the Triticeae. It is cultivated worldwide in temperate climates and is a central basis of bread, baked goods, pasta products, starch products and many processed foods. The grain consists of endosperm, aleurone layer, bran and germ. Depending on use, whole grains, flours of different extraction rates, bran, germ, starch, gluten, wheatgrass or extracts are obtained. These fractions have very different compositions and technological properties.

Phytochemistry

Wheat grains contain primarily starch, storage proteins, fibre, lipids, minerals, vitamins and phenolic accompanying substances. The storage proteins gliadins and glutenins together form gluten, which is crucial for baking properties, dough elasticity and volume formation. Bran and the aleurone layer contain fibre, arabinoxylans, minerals and phenolic acids such as ferulic acid. The germ contains lipids, tocopherols, phytosterols and enzymatically active fractions. Wheatgrass has a different profile with chlorophyll, minerals and leaf metabolites. Cultivar, site, fertilisation, harvest, storage and processing influence protein quality, starch behaviour, enzyme activity and secondary accompanying substances.

Traditional Uses

Wheat is one of the oldest and most important crops of settled agriculture. Bread, porridge, flatbreads, baked goods, beer and fermentation products shaped the diets of many cultural regions. In Europe, bread wheat became the basis of numerous baking traditions, whereas durum wheat plays a different role in pasta. Bran, germ and whole-grain products have their own nutritional histories. The cultural role of wheat is closely linked with agriculture, storage, milling technology, baking and social food history. Historical-use contexts concern predominantly foods and must be distinguished from concentrated speciality fractions or isolated gluten.

Current Research

Research on Triticum aestivum encompasses breeding, yield, climate adaptation, disease resistance, gluten structure, baking quality, starch physics, whole-grain research, germ fractions, allergens, coeliac disease, non-coeliac wheat sensitivity and processing technology. Gluten proteins are intensively studied because they are technologically desirable but problematic for certain groups of people. Food-chemistry research addresses ferulic acid, arabinoxylans, mineral bioavailability and process changes caused by milling, baking or fermentation. Wheatgrass and germ extracts are studied separately as speciality raw materials. Findings from isolated fractions cannot be transferred to whole grains or traditional foods.

Sources

• Plants of the World Online: Triticum aestivum L.; Royal Botanic Gardens, Kew.
• Standard cereal-chemistry and food-technology literature on bread wheat.
• Specialist literature on wheat allergens, gluten, coeliac disease and whole-grain fractions.