Published by the technical research center of Finland VTT, the paper investigated the impact certain processing steps had on the nutritional content of oats. The aim was to find ways to improve the dietary fiber value of oats and thus drive its appeal as an ingredient in the food sector, especially snacks.
Findings showed certain process steps significantly improved the nutrition of oat fractions, particularly defatting.
“After supercritical carbon dioxide extraction, oat beta-glucan and protein were enriched into higher concentrations than in any existing commercial dry fractionation process,” author Juhani Sibakov wrote.
While the defatting step yielded the largest increase in beta-glucan content, a combination of steps - grinding, air-jet milling, air classification and separation – heightened levels further, he said. A beta-glucan content of up to 56% could be achieved, he added.
Processing tricks: Grinding, separation and air milling
Use of ultra-fine grinding and electrostatic separation, for example, showed good potential in concentrating the beta-glucan further, Sibakov said.
“Higher beta-glucan concentrations were reached by electrostatic separation, because the separation was based on the acquired charge of the particles, not on their size and density as in air classification,” he wrote.
Air-jet milling also showed promise in further enriching beta-glucan cell walls from protein and starch particles.
Nutritional punch, improved texture
Sibakov said in particular, “the defatted oat fractions were suitable ingredients for expanded snacks”.
Higher beta-glucan concentrations enabled manufacturers to use less defatted oat endosperm flour in expanded snacks for the same nutritional punch as regular wholegrain oat flour, he explained.
“A similar level of dietary fiber as in wholegrain oat flour-extrudates was achieved when 10% of oat bran concentrate was added in endosperm flour.”
In addition, defatted oat endosperm flour created superior texture in extruded snacks, the researcher said.
In particular, adding water-insoluble fractions of oat bran concentrate gave higher expansion and lower hardness values to the extruded snack products.
Driving oat use in industry
The beta-glucan enriched oat fractions developed by using a combination of processing steps could be used to develop functional foods, Sibakov said. The beta-glucan content would also enable many to make EU-approved health claims on cholesterol lowering, he added.
However, the research said there remained plenty more possibilities to improve the fractionation and depolymerisation processes of oat production. Should these be followed up with research and development, usability of oat beta-glucan could further increase, he said.
Source: VTT Science 67
Published October 15, 2014
“Processing of oat dietary fibre for improved functionality as a food ingredient”