Functional bread enriched in bioactive compounds with pearled fractions of barley.

Bread is a fermented food base of the human nutrition worldwide. Despite the high variability of this food (recipes, ingredients, texture, form, colour and organoleptic profile) bread’s chemical composition is fundamentally linked to the cereal/ingredients used in preparation. The nutritional value of bread is largely linked to carbohydrates content (starch), but many other bioactive can interest the nutritional value of this food. Barley and wheat, depending on the varieties as well as the origin and the agronomical practices, are rich in bioactive compounds like fibre and polyphenols, particularly concentrated in the bran fraction. A strategy to maximise the health benefits of wheat-based products could be to enrich refined flour with fractions of external kernel layers, obtained using grain dry-fraction technologies. Sequential pearling has usefully applied to treat different cereals, like wheat (Sovrani et al., 2012), sorghum (Luthria and Liu, 2013) and barley (Gamel et al., 2012), in order to obtain different fractions rich in bioactive compounds. The principal aim of this work was to evaluate the effect of wheat flour substitution with different percentages of pearled barley fractions on chemical composition and technological properties of bread. Considering the different composition of pearled barley fractions (external fractions are richer in antioxidants and insoluble fibre than internal layers and residual kernels, which, on the contrary, contain most β -glucans), two different fractions (cv Mona, an hulless two-row variety) were employed, specifically the most external (corresponding to the 0-5% of kernel weight) and the most internal (residual 75% weight) fractions. Two different series of substituted flours were obtained (substitution percentages: 5, 10, 15, 20 and 25%) and used to prepare bread. All the samples and the corresponding blanks, obtained using not-substituted refined commercial flour, were analysed for the chemical composition (humidity, proteins, ashes, fibre, β-glucans and total polyphenols), the antioxidant activity, the rheological properties (Mixolab® parameters) and the physical bread properties (volume, crust colour, instrumental crunchiness and crumb texture profile analysis parameters). As expected, the use of these novel enriched flours improved the functional properties of the breads, in accord with the original properties of the barley fractions. In the case of β-glucans content, a greater increase was observed when internal fraction was employed (from 0.13% to 1.13% and from 0.18% to 0.89%, for the blanks and the 25%-substitution with internal and external fraction, respectively). Concluding, the modulation of the pearling technology and the possibility to mix different fractions can lead to the production of new functional flours useful for the production of bread with nutritional added value and specific functional properties.