Influence of α-amylase and xylanase on the chemical, physical and volatile compound properties of wheat bread supplemented with wholegrain barley flour

Abstract

The Irish barley variety “Sanette” was incorporated at 30 % inclusion levels into a wheat bread formulation. Baking enzymes were used to improve the baking characteristics of the final breads. The enzymes studied were fungal α-amylase, xylanase and a combination of the two enzymes. Volume, cell structure, crumb texture, compositional analysis and volatile compounds of the baked breads were evaluated. Experiments were replicated thrice, and the data were analysed using a one-way ANOVA for significant differences less than p < 0.05. Baking results illustrated that using xylanase on its own and in combination with fungal α-amylase resulted in breads with a larger loaf volume (3.16 and 3.05 mL/g) in comparison with the control (2.69 mL/g, p < 0.006). Crumb softness increased following the addition of the α-amylase and xylanase combination (6.94 N) compared to the control (11.17 N, p < 0.001). The use of barley flour in the breads increased the concentration of isoamyl alcohol from the alcohol group and decreased the concentration of compounds from the pyrazine and sulphur groups. Using the enzyme combination resulted in volatile compounds similar to the 30 % wholegrain wheat bread, e.g. 2-methyl butanal and 2,3-butanedione. The incorporation of barley into a wheat bread formulation on a 30 % replacement basis in combination with the two enzymes (α-amylase and xylanase) increased the total amount of fibre present in the bread (6.3 %) compared to the 30 % wholegrain wheat bread (4.8 %).