Differences between wheat flour and spelt flour – a scientific study

We like to share with a summary of the scientific article "High resolution proteomics reveals differences in spelt and wheat flour proteome that represent targets for wheat sensitivity research" published by Muhammad Afzal, Jens Pfannstiel, Julia Zimmermann, Stephan C. Bischoff, Tobias Würschum, C. Friedrich H. Longin on the website www.nature.com/scientificreports. In the study the proteins of spelt are compared with those of wheat flour to understand why one creates more allergic reactions or intolerances than the other.

As this is a text with many technicalities, we consider that it is necessary to clarify some terms in advance, such as proteomics, to help understanding the study and the techniques that the researchers have used to find the results.

The "omics" are relatively recent sciences that, supported by very relevant technological advances, allow studying a great number of molecules, involved in the functioning of an organism, for example genomics, metagenomics, proteomics, metabolomics and more.Genomics are related to the genome, where we find the genetic information we inherit from our parents. Metagenomics studies the genetic material, which is obtained directly from environmental samples. This is very useful in the study of the Culture Mother Mass. Proteomics are the large-scale study of proteins, in particular their structure and function. Metabolomics are the scientific study of chemical processes involving metabolites, also very useful in the study of bread after baking.

The genome is formed by the deoxyribonucleic acid (DNA) that is in the nucleus of the cells of our body. Just as genomics studies the chains of genes to find their proteins, in recent decades, technological progress has allowed the large-scale study of many genes, proteins and metabolites, allowing the creation of the aforementioned omics and other diverse ones. Each one of these areas has helped to better understand the cause of certain diseases. In addition, the application of knowledge about omics to the clinic can be used to make an earlier diagnosis or to prevent the development of a disease. You can read more about this topic here http://revista.unam.mx/vol.18/num7/art54/index.html

To go back to the article we know that "consumption of bread wheat (Triticum aestivum ssp. Aestivum) products can cause different diseases in humans such as celiac disease (CD), allergic reactions and sensitivity to non-celiac wheat (NCWS) that can affect up to 10% of the human population".

Quote from the study

Spelt (Triticum aestivum ssp. Spelta) is a wheat species defined as a different subspecies of bread wheat. Both spelt and bread wheat are hexaploids that have the genome AABBDD. Despite these similarities, millers and bakers selling spelt and bread wheat products were confronted by consumers who claimed to have health problems. Ranging from symptoms such as flatulence to diseases such as neurodermatitis when eating bread wheat, but not when eating spelt products.

The possible differences in the proteomes of the spelt and the flour of bread wheat have been investigated with the purpose of being able to find the causes and differences. For this purpose, 15 representative varieties of the current production of spelt and bread wheat in Germany were used, which were grown at three different test sites and their flour proteome was analyzed using the Nano LC-ESI-MS / MS technique.

The objectives of this research have been (1) to investigate whether spelt and bread wheat flour contain different proteins, which could be additional targets for NCWS research; (2) to compare variation between and within species; and (3) to elaborate on the impact of environment versus genetics on protein expression in order to discuss possible consequences for the future wheat supply chain, as well as for human and animal nutrition. 

 Results of the study 

The study identifies that spelt and bread wheat belong to the same species but are different subspecies. To compare spelt and breadmaking wheat, a dendrogram is generated using hierarchical groupings of the 15 spelt varieties and 15 breadmaking wheat based on all the proteins that were environmentally stable expressed in at least one variety.

A total of 3050 proteins in spelt and 2770 proteins in bread wheat are detected. Respectively, which seems to be the largest number ever reported for spelt. Interestingly, even more proteins are identified in spelt samples than in bread wheat samples, although the wheat reference protein sequence must be used also for spelt, since apparently there is no other published reference in this regard.

Of the total number of identified proteins, only 1555 proteins were detected in spelt and 1166 in bread wheat in a subset of the field locations. The study shows that, depending on the specific environmental conditions in the growing places, it is not possible to identify a specific trend that shows, for example, that most of the proteins were expressed in one place and in less quantity in another place. 

For that reason, additional research was focused on these proteins, which were consistently expressed at all test sites in at least one species of each variety.

We are talking about 1495 proteins in spelt and 1604 proteins in bread wheat. In these proteins, a great impact of the environment on their level of expression has been observed. Heritability is a feature that determines the level of expression of a protein and can be influenced by genetic versus environmental factors.

These findings are consistent with data on the crude protein content of wheat grains, classically determined by the Dumas combustion principle (ICC standard method 167, ICC, Vienna, Austria). This crude protein content of the grain is greatly affected by environmental conditions, including the amount and type of nitrogen fertilization, climatic conditions, and soil types that influence the availability of nutrients to the plant.

The study's conclusions clearly show that the expression of many proteins was influenced primarily by the environmental conditions in which they were grown. Considering the variable climatic conditions in cereal production, only proteins that are largely independent of environmental effects and, instead, are mainly controlled by the grain's genetics, can be effectively manipulated along the wheat supply chain. Among several thousand proteins, we identified several hundred of these proteins in spelt and bread wheat.

In addition, it has been possible to demonstrate that approximately one third of the detected proteins differed between spelt and bread wheat. Moreover, by concentrating in the study only on proteins with high heritability, a list of interesting candidate proteins for future research on wheat sensitivity were presented.