Physical and sensory properties of corn snack products enriched with food industry by-products

By-products of plant food processing, which are rich in fibre and bioactive compounds, have attracted much attention for their functionality and potential as food ingredients in recent years. Extrusion, as a continuous process with high versatility and productivity, offers a good avenue to incorporate different types of by-products in ready-to-eat snacks and breakfast cereals. In addition, incorporating of these by-products can improve nutritional value of extruded products that are otherwise carbohydrate-rich, high glycaemic products. The aim of this study was to investigate the possibility of application brewer’s spent grain (BSG), sugar beet pulp (SBP) and apple pomace (AP) in production of corn snack products. By-products were mixed with corn grits at different ratios (0/100 ; 5/95 ; 10/90 and 15/85), where in the mixtures with BSG and SBP pectin was added at level 1% d. m., with the aim to produce products with properties of ready-to-eat snacks. Prepared samples with 15% of moisture content were extruded in the laboratory single screw extruder at temperature profile 135/170/170 °C, using a screw with compression ratio 4:1 and die with 4 mm diameter. Obtained extrudates were air-dried overnight, and physical and sensory properties of extrudates were determined. The obtained results showed that addition of by-products to corn grits resulted in decrease of expansion ratio (ER) and fracturability, whereas bulk density (BD) and hardness of extrudates increased. Acceptable scores in sensory evaluation received all samples with brewer's spent grain and sugar beet pulp (with addition of 1% pectin), and samples with 5 and 10% of apple pomace. It can be concluded that these three by-products can be successfully incorporated in corn grits with the aim of production acceptable expanded corn snack products.