Side-stream products of malting have potential in food

Researchers have found the waste product generated from the process of malting has antioxidant properties and has potential to be used in the food industry.

Malting, the processing of cereal grains into malt, generates rootlets as a side-stream product, which is currently mostly utilised as animal feed. However, this leftover material has not only a high protein content, but also high amounts of phytochemicals, according to a recent study from the University of Eastern Finland, published in npj Science of Food.

The study utilised metabolomics to analyse samples from grains of four cereals typically used in malting: barley, rye, wheat and oats. The researchers were particularly interested in phytochemicals, which are bioactive compounds produced by plants. Many phytochemicals have been shown to work as antioxidants and to have other potential beneficial health effects.

Samples were taken during several steps of the malting process, such as from malted grains, wort and water extract, as well as from rootlets and spent grain, the side-stream products of the processing. The main finding of the study was the observation of 285 different phytochemicals, most of which were found in the side-stream products, especially the rootlet.

The germination occurring in the beginning of malting increased the levels of several phytochemicals compared to the unprocessed grains, and also produced compounds that were not abundantly present in the original grains.

The study said it has been estimated that the protein contained in the side-stream products of malting could fulfil the annual protein need for five million people.

The biggest challenge in utilising the side-stream products of malting in foods is their taste and other sensory properties, which may not be acceptable as such, according to lead author Ville Koistinen from the University of Eastern Finland.

“They would likely require further food processing, such as fermentation, so that they could be used to increase the nutritional value of white bread, for example,” Koistinen said.

The health effects of phytochemicals are a hot topic among scientists because their mechanisms are largely unknown.

“However, we do have increasing evidence that the protective effect of plant-based foods against several diseases is at least partly attributable to the phytochemicals contained within them, and that these effects can only be obtained by eating plants, not from pills or supplements containing individual compounds.”

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