Effect of Brewer’s Spent Grain Addition on Properties of Corn Extrudates with an Increased Dietary Fibre Content

Abstract

The effect of brewer’s spent grain addition (5, 10, 15 and 20% w/w) on selected properties of extrudates produced from corn grits with various moisture contents (12.5%, 13.5%, 14.5% and 15.5%) was analysed in this study. It was shown that an addition of brewer’s spent grain (BSG) to extrudates reduces expansion and increases density of the product. The changes are dependent on raw material moisture content. A higher addition of brewer’s spent grain is reflected in higher values of Water Absorption Index (WAI). At a raw material moisture content exceeding 12.5% there is no correlation between the content of brewer’s spent grain and WAI. Water Solubility Index (WSI) values decrease with an increasing content of brewer’s spent grain in the sample, irrespective of moisture content in the extruded mixture. An addition of BSG to extrudates makes it possible to obtain a product with a high content of dietary fibre, particularly cellulose and hemicellulose fractions. Extrudates produced from a raw material with a moisture content of 12.5% received the highest scores in sensory evaluation. At such a moisture content of the raw material an acceptable product with a 15% brewer’s spent grain content was obtained. Higher additions of BSG resulted in a reduced expansion, increased density and lower desirability of the product due to the specific aroma and after-taste of BSG.