Gluten traced back to specific grains

CSIRO has announced it can detect gluten in the less well-studied grain rye - the final gluten-containing grain.

CSIRO was first able to detect specific glutens in wheat in 2015, barley in 2016, and oats in 2018.

Existing commercial tests can only tell if gluten is present in a food but not the grain it came from.

The various detection kits available also give variable results of how much gluten is present.

CSIRO protein analytics expert Michelle Colgrave said completing the picture with rye could help consumers and food manufacturers.

"Being able to detect any protein in diverse foods and beverages will help food companies ensure that what's in the pack is what's on the pack, and help consumers trust pack labelling around gluten-free claims," Profressor Colgrave said.

"This technology offers many applications for the food industry from helping track contamination in their raw ingredient supply chain, to improving product quality, food safety and meeting regulations."

The researchers analysed 20 cultivars of rye from 12 countries, which they milled into flour, extracted the gluten proteins and used high resolution mass spectrometry to identify and quantify the proteins.

The analysis revealed six proteins specific to all rye varieties but that do not appear in other grains.

Detecting gluten proteins in their original grain is relatively simple, but when they are in food products available at the supermarket and have been baked, extruded or processed in other ways with other ingredients such as salt and sugar, it is a lot more complex.

The team tested a range of commercial flours, breakfast cereals and snack foods and detected the six rye proteins in all the foods that contained rye as a labeled ingredient.

They found one "gluten-free" breakfast cereal that contained trace amounts of rye, which did not appear on the ingredients list, and one sample of flour from the wheat-related grain, spelt, which was contaminated with about 2 per cent rye.

The research has been recently published in the American Chemical Society's Journal of Proteome Research.

Next steps are to validate the method's ability to accurately quantify the level of glutens present in a food and work with the food industry and commercial testing laboratories to help commercialise the technology.