Chapter 6 - Gluten quantity and quality in wheat and in wheat-derived products

Consuming cereals, including wheat, is much older than agriculture. Wheat selection, cultivation, and processing gradually developed in prehistorical times. The wheat species einkorn, emmer, and spelt wheat remained major human staples until the last century when durum wheat for pasta products, and especially bread wheat oust the ancient grains from the market. Wheat species may hybridize, resulting in new wheat species, some in preagricultural times, but others induced more recently. Traditional wheat cultivation with mixed species resulted in landraces well adapted to local environments. More than half a million accessions are stored in gene banks globally. Modern breeding applies the genetic flexibility of wheat. The bread wheat genome has been sequenced, and advanced wheat breeding and processing technologies have been developed, aiming, for example, at the development of celiac-safe food. Discussing wheat in the context of diversity and health requires a production chain-wide approach regarding gluten accumulation and health effects. The protein fraction of wheat grains includes several families of gluten genes: (1) high-molecular-weight glutenins, 6%–10% of the gluten fraction, (2) sulfur-rich alpha- and gamma-gliadins, and B- and C-type low-molecular-weight (LMW) glutenins, 70%–80% of the gluten fraction), and (3) sulfur-poor omega-gliadins and D-type LMW glutenins, 10%–20% of the gluten fraction. The glutenins form the three-dimensional network in wheat dough and are responsible for elasticity, while gliadins convey viscosity. The unique characteristics of wheat gluten are part of the reason why wheat is used as a very versatile component in many food products. Over 30% of supermarket packed processed foods contain bread wheat or derived ingredients. A connection between the consumption of processed foods and the incidence of chronic diseases is suggested, but consumption of whole grain (wheat) foods is advised to contribute to chronic disease prevention.