New extraction technique leads to enriched beta-glucan

Dry extraction with supercritical carbon dioxide can enhance the separation of oat beta-glucan, starch and protein in distinct fractions, meaning a higher quality final product, according to new research.

The study, published in the Journal of Cereal Science, reported that oats defatted by supercritical carbon dioxide – a process involving the use of high pressure carbon dioxide which acts as a liquid in its supercritical state – leads to better separation of bran fractions.

The researchers, led Juhani Sibakov of the VTT Technical Research Centre of Finland, said that the novel dry fractionation technology “enriched the valuable compounds of oats.”

“By defatting non-heat treated grains with supercritical carbon dioxide, we obtained a porous matrix which was easy to mill into very fine particles and then fractionate by air classification,” said Sibakov

They added that the oat bran concentrate obtained via the processes had higher beta-glucan content than existing products produced with dry fractionation techniques.

“The high beta-glucan content enables formulations for functional food products suitable for cholesterol lowering … The high purity protein concentrate could serve as a substitute for animal and soy proteins,” said the researchers.

Sibakov said the study also tested the industrial applicability of the process by running a trial with 2310 kilograms of oats. He said that the trail proved that the defatting and dry fractionation process was industrially and commercially viable.

Study details

Sibakov said that lipid removal by supercritical carbon dioxide extraction enabled the concentration of the main components of oats – starch, protein, lipids and cell walls – into specific fractions.

“The defatted material could be milled to a much finer flour as compared to the non-defatted oats, resulting in a flour in which starch granules were mostly loose and not embedded in cells,” reported the authors.

They said that lipid extraction from the oat raw material before fractionation made it possible to obtain a fraction with a beta-glucan concentration of 33.9 per cent.

The removal of lipids also enabled separation of an oat protein concentrate with a protein concentration of 73 per cent.

“Usually if you want to get very enriched fractions then you have to rely on wet extraction methods, using a solvent like ethanol or hexane. By using a dry extraction method we don’t have to dry the product after to get a powder, also there is no aftertaste associated with the process, which there can be for wet extraction methods,” said Sibakov.

“The whole process can be scaled up to an industrial scale,” he added.

Source: Journal of Cereal Science