Use of air classification technology as green process to produce functional barley flours naturally enriched of alkylresorcinols, β-glucans and phenolic compounds

- Two barley fractions (coarse and fine) were obtained by air classification.
- Coarse fraction is naturally enriched in bioactive compounds.
- Coarse barley fraction showed double concentration of β-glucans than whole meal.
- Phenolic compounds and alkylresorcinols were more abundant in coarse barley fraction.
- Coarse fraction can be used into food formulations to obtain enriched/functional foods.

In the last years, food researchers and food industries focused their attention on the content of bioactive compounds in food and in the re-use of food wastes. Sometimes, these goals can be obtained at the same time by the use of sustainable technologies. Cereal milling processes generate large amounts of cereal by-products that usually were used in zootechny or they represented the raw material for the extraction of bioactive compounds using solvents or expensive processes. The aim of this study is to propose air classification as a green technology for the production of barley flours using the whole grain and avoiding by-products production. Three non-waxy and one waxy barley cultivars were air-classified.The results demonstrate that barley coarse fraction showed high amounts of β-glucans (until two-fold higher than whole meal). The same fraction showed concentration of free and bound phenolic compounds that were 1.2-1.3 times higher than whole meal. This improvement was confirmed by the antioxidant activity of barley fraction; in fact, both DPPH and ABTS tests reported the highest values when coarse fraction was analyzed. Moreover, as far as we are concerned, alkylresorcinols were determined in barley air classified fractions for the first time. As reported for phenolic compounds, their content increased 1.2-1.4 times in coarse fraction compared to whole meal.In conclusion, air classification allows the production of two fractions from whole grain. Coarse fraction resulted naturally enriched in bioactive compounds.