| Extrusion is one among the major technologies used in food manufacturing. When extrusion is used to make puffed products such as breakfast cereals, it is a high temperature short time process, in which high shear and heat are applied on low moisture feed. During extrusion of cereal based food materials, several molecular transformations such as starch gelatinization and protein denaturation occur, leading to changes in the physico-chemical properties of the extrudates.;The major objectives of this study were to make extruded ready-to-eat (RTE) breakfast cereal from quinoa, fortified with cranberry concentrate and to study the effect of extrusion on the physico-chemical properties of the extrudates. Cassava flour was used as an extrusion aid for puffing. The base feed consisted of 50-50 blend of quinoa and cassava. Phenolic rich cranberry concentrate had anthocyanins which acted as natural colorants for the extrudates.;A single screw extruder equipped with a 4:1 compression ratio screw, set at 130 RPM, was used with a 4.5 mm diameter die hole. A 33 Box- Behnken Design was used to design the experiments for three independent variables: barrel temperature (120 °C, 140 C, 160 °C), cranberry solids (3 %, 4 %, 5 % (d. b.)), and feed moisture (16 %, 18 %, 20 % (w.b.)). Physical properties such as Radial Expansion Index (REI), Bulk Density (BD), Breaking Strength (BS), Hue, Chroma, Water Absorption Index (WAI), and Water Solubility Index (WSI) along with chemical properties such as Total Phenolic Content (TPC) and anthocyanin content were evaluated.;Extrudates collected at barrel temperature of 160 °C, 16 % feed moisture and 4 % cranberry solids showed lowest Bulk Density of 0.281 g/ml and Breaking Strength of 0.46 N/mm2. From the response surface analysis, it was found that barrel temperature and feed moisture were the two most important variables that affected the physical properties. The TPC of extrudates collected at higher barrel temperatures were found to contain higher phenolic values (∼ 80 mg GAE/100 g d.m.), probably due to the formation of Maillard products. Extrudates collected under 140 °C barrel temperature, 16 % feed moisture and 5 % cranberry solids showed maximum anthocyanin content of 9.63 mg / kg d.m.;This study will open new avenues to develop gluten free extruded products that can be naturally colored with antioxidant loaded fruit concentrates. |
