Properties of corn snack products enriched with food industry by-products

Cilj ovog istraživanja bio je utvrditi mogućnost primjene nusproizvoda prehrambene industrije (pivski trop, izluženi repini rezanci i trop jabuke), u udjelima 5, 10 i 15 %, u proizvodnji kukuruznih snack proizvoda, odnosno aditiva u proizvodnji pekarskih proizvoda. Istraživanje je obuhvatilo određivanje fizikalnih, reoloških i kemijskih svojstava neekstrudiranih i ekstrudiranih uzoraka te senzorskih svojstava odabranih snack proizvoda. Dobiveni rezultati pokazuju kako se dodatkom nusproizvoda smanjio ekspanzijski omjer i lomljivost, a povećala tvrdoća i nasipna masa ekstrudata. Dodatak nusproizvoda i postupak ekstruzije imali su značajan utjecaj na promjenu boje i osnovni kemijski sastav. Nadalje, viskoznost vrha te topla i hladna viskoznost smanjene su dodatkom nusproizvoda i postupkom ekstruzije. Ekstruzijom se značajno povećao indeks apsorpcije i indeks topljivosti u vodi te stupanj oštećenosti škroba. Dodatkom nusproizvoda značajno se povećao udio netopljivih i topljivih vlakana. Ekstruzija je uzrokovala smanjenje udjela netopljivih vlakana i rezistentnog škroba, a povećanje udjela topljivih vlakana i nerezistentnog škroba. Udio ukupnih polifenola smanjio se, a antioksidativna aktivnost kod većine uzoraka povećala se nakon provedenog procesa ekstruzije. Veći udjeli akrilamida i hidroksimetilfurfurala utvrđeni su kod bolje ekspandiranih uzoraka te ekstrudata s većim udjelom nusproizvoda. Prihvatljivu senzorsku ocjenu dobili su svi uzorci s pivskim tropom i repinim rezancima (uz dodatak 1 % pektina) te uzorci s 5 i 10 % tropa jabuke.The aim of this study was to investigate the possibility of using food industry by-products (brewer's spent grain, sugar beet pulp and apple pomace), in proportions of 5, 10 and 15%, in production of corn snack products or additives in production of bakery products. The research included determination of physical, rheological and chemical properties of non-extruded and extruded samples, and sensory properties of selected snack products. The obtained results show that the addition of by-products decreased expansion ratio and fracturability, and increased hardness and bulk density of extrudates. By-products addition and extrusion process had a significant effect on color change and basic chemical composition. Furthermore, peak, hot and cold viscosities decreased with addition of by-products and after extrusion process. Extrusion significantly increased water absorption and water solubility index, and starch damage. With addition of by-products content of insoluble and soluble dietary fiber significantly increased. Extrusion caused a reduction of insoluble fiber and resistant starch content, and increase of soluble fiber and non-resistant starch content. Total phenolic content decreased, and antioxidant activity in most of samples increased after extrusion process. Higher contents of acrylamide and hydroxymethylfurfural were found in samples with better expansion, and extrudates with higher content of by-products. 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