A research team compares wheat varieties spanning 120 years.
The number of people affected by coeliac disease or sensitivity to wheat or gluten has risen sharply in recent years.
Attempting to understand why this might have occurred, researchers from the Leibniz-Institute for Food Systems Biology at the Technical University of Munch and the Leibniz Institute of Plant Genetics and Crop Plant Research, Germany, have been investigating whether modern wheat varieties contain more immunoreactive protein than in the past. The research has been published in Journal of Agricultural and Food Chemistry.
The researchers explain that wheat grain comprises 70% starch. Protein is about 10%-12%, with gluten accounting for the majority of this. Gluten is a compound mixture of different protein molecules which can roughly be divided into two groups; gliadins and glutenins. It is believed that gliadins are responsible for the immune reactions that impact many people.
Investigating differences between the old and modern varieties of wheat the research team looked at the protein content of 60 preferred wheat varieties between the years 1891 and 2010. This was made possible due the extensive seed archive at the Leibniz Institute of Plant Genetics and Crop Plant Research.
Cultivating the different varieties under the same conditions during 2015, 2016 and 2017, the researchers found that overall; modern wheat varieties had slightly less protein than older ones. In contrast the gluten content remained constant over the 120 years, although the composition of the gluten was found to have changed slightly.
While the proportion of critically viewed gliadins fell by around 18%, the proportion of glutenins rose by around 25%. The researchers also observed that higher precipitation in the year of harvest was accompanied by higher gluten content in the samples.
Katharina Scherf, Professor at the Karlsruhe Institute of Technology said ‘Surprisingly, environmental conditions such as precipitation had an even greater influence on protein composition than changes caused by breeding. In addition, at least on the protein level, we have not found any evidence that the immunoreactive potential of wheat has changed as a result of cultivation factors.’
However, Scherf pointed out that not all protein types contained in wheat have been investigated with regard to their physiological effects, and therefore there was still a lot of work to be done.