RESUMEN
In order to analyze the effects of extrusion temperature (T: 164, 182, 200 °C) and grits moisture content (g/100 g sample) (%M: 14, 16.5, 19) on textural and physicochemical properties of red sorghum extrudates, whole grain flour was extruded according to a factorial experimental design. The higher values for specific mechanical energy consumption (1006.98 J/g) and expansion (3.36) were obtained at 164 °C-14%M and for sensorial hardness at 164 °C-19%M. While for specific volume, the highest value (10.41 cm³/g) was obtained at 200 °C-14%M. Water solubility and water absorption were directly related with T and inversely with M. Microscopic observation of the samples indicates that the greatest cooking degree was obtained at 200 °C-4%M and the lowest at 164 °C-19%M. Extrusion at 182 °C-14%M allows obtaining an expanded product with good properties. Proximal composition did not show statistically significant differences with raw sample. Extruded sample showed a 25.4% reduction of available lysine and a 31% increase in protein digestibility.
Asunto(s)
Fibras de la Dieta/análisis , Harina/análisis , Manipulación de Alimentos , Semillas/química , Sorghum/química , Argentina , Fenómenos Químicos , Culinaria , Fibras de la Dieta/metabolismo , Proteínas en la Dieta/análisis , Proteínas en la Dieta/química , Proteínas en la Dieta/metabolismo , Digestión , Dureza , Calor/efectos adversos , Humanos , Hierro de la Dieta/análisis , Hierro de la Dieta/metabolismo , Lisina/análisis , Lisina/metabolismo , Valor Nutritivo , Proteínas de Plantas/análisis , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Semillas/ultraestructura , Sensación , Solubilidad , Sorghum/ultraestructura , Almidón/análisis , Almidón/química , Almidón/metabolismo , Almidón/ultraestructura , Agua/análisis , Zinc/análisis , Zinc/metabolismoRESUMEN
The utilization of whole grains in food formulations is nowadays recommended. Extrusion cooking allows obtaining precooked cereal products and a wide range of ready-to-eat foods. Two rice varieties having different amylose content (Fortuna 16% and Paso 144, 27%) were extruded using a Brabender single screw extruder. Factorial experimental design was used to study the effects of extrusion temperature (160, 175, and 190°C) and grits moisture content (14%, 16.5%, and 19%) on extrudate properties. Specific mechanical energy consumption (SMEC), radial expansion (E), specific volume (SV), water absorption (WA), and solubility (S) were determined on each extrudate sample. In general, Fortuna variety showed higher values of SMEC and S (703-409 versus 637-407 J/g; 33.0-21.0 versus 20.1-11.0%, resp.) than those of Paso 144; on the contrary SV (8.64-3.47 versus 8.27-4.53 mL/g) and WA tended to be lower (7.7-5.1 versus 8.4-6.6 mL/g). Both varieties showed similar values of expansion rate (3.60-2.18). Physical characteristics depended on extrusion conditions and rice variety used. The degree of cooking reached by Paso rice samples was lower than that obtained for Fortuna. It is suggested that the presence of germ and bran interfered with the cooking process, decreasing friction level and broadening residence time distribution.