The addition of brewer's spent grain (BSG), sugar beet pulp (SBP) and apple pomace (AP), on the nutritional properties of directly expanded snack products based on corn grits was investigated. Snack products were produced in a laboratory single screw extruder with the addition of 5, 10 and 15% d. m. of these by-products in corn grits. Chemical composition, total phenolic content, antioxidant activity, dietary fiber, resistant starch, starch damage and pasting properties of the mixtures and extruded samples were determined. Extrusion process and by-product additions had a significant effect on the proximate chemical composition. All three by-products increased contents of both soluble and insoluble dietary fiber, while the extrusion caused a reduction of insoluble fiber and increase of soluble fiber. After the extrusion process starch damage and antioxidant activity increased, while resistant starch content and total polyphenol content decreased. According to obtained results, it can be concluded that the investigated by-products can be used in the production of nutritionally more valuable corn snacks.
Keywords: by-products; chemical composition; corn snacks; extrusion; nutritional value.