Textural characteristics of extruded product from different types of cereal and with varying water during extrusion process

Zadatak ovoga rada bio je ispitati utjecaj dodatka pšeničnog, kukuruznog i rižinog brašna te različite količine dodane vode u procesu ekstruzije na strukturu ekstrudiranih žitarica za doručak. Pri različitim dodacima vode u procesu ekstruzije (21 %, 23 % i 27 %) proizvedene su ekstrudirane kuglice od mješavine pšenične krupice s pšeničnim, kukuruznim ili rižinim brašnom. Uzorci su pripremljeni sa i bez slatkog premaza. Teksturalna svojstva suhih ekstrudiranih kuglica i kuglica pripremljenih kao obrok s mlijekom provedena su pomoću senzorskih metoda i instrumentalno pomoću analizatora teksture TA.XT Plus. Weibull jednadžba se koristila za nelinearnu estimaciju eksperimentalnih podataka za apsorpciju mlijeka i promjenu hrskavosti u pripremljenom obroku tijekom vremena. Hrskavost suhih ekstrudiranih uzoraka bez premaza je bila mnogo veća od hrskavosti uzoraka s premazom, najveću hrskavost imali su uzorci od čiste pšenične krupice i brašna, a najmanju, uzorci od mješavine pšenične krupice i kukuruznog brašna. Povećanjem količine dodane vode u procesu ekstruzije smanjivala se hrskavost gotovog proizvoda. Apsorpcija mlijeka i gubitak hrskavosti u obroku s mlijekom bili su mnogo jače izraženi i brži kod uzoraka bez premaza u odnosu na uzorke s premazom. Također su utvrdene statistički značajne korelacije između velikog dijela podataka dobivenih ispitivanjem apsorpcije mlijeka, instrumentalnim određivanjem hrskavosti i senzorskim ispitivanjem.Textural characteristics of ready-to-eat breakfast cereals were evaluated in order to determine the influence of wheat, corn and rice flour, as well as varying water addition during extrusion process. Extruded breakfast cereal balls were made of wheat semolina in combination with wheat, corn or rice flour. Three different levels of water addition (21%, 23% and 27%) were used during extrusion process. Samples were prepared with and without surface sugar coating. Sensory and instrumental assessments (TA.XT Plus) were used to evaluate textural attributes of dry samples and samples during immersion in milk. Weibull equation was used for nonlinear estimation of experimental data obtained for milk absorption and crispiness as a function of time in the bowl. Crispiness of dry extruded balls without coating was much higher than for samples with coating. The highest values for crispness were observed for wheat extruded balls and lowest for samples with corn flour addition. Increasing water addition during extrusion process significantly increased crispness of ready-to-eat breakfast cereals. Rate of milk absorption and loss of crispiness were significantly higher for samples without coating than for samples with coating. Also, significant correlations were found between data obtained from milk absorption measurements, sensory scores and instrumental evaluation