Physical and Sensory Properties of High Added Value Rice Extrudates

Rice extrudates enriched with freeze dried carrot powder were produced using a twin screw extruder, operated at various conditions of screw speed (150–250 rpm) and temperature (140–180 °C). Different carrot concentrations (5–10 %) were added in rice flour and the mixtures were equilibrated at three moisture contents (14–20 %). A comprehensive understanding of the effect of process conditions and material characteristics on structural, textural, and sensorial properties of the produced extrudates was examined in the present study. Simple mathematical power models were used in order to correlate properties with extrusion conditions. According to regression analysis, moisture content and carrot concentration increment led to the production of denser extrudates, while a temperature and a screw speed rise significantly decreased apparent density. Expansion ratio showed a negative relationship with moisture content, carrot concentration, and temperature. In addition, textural properties were inversely related to expansion ratio, indicating the increased crispness of highly expanded products. Finally, sensory analysis indicated that increased moisture content and carrot concentration were highly correlated with loss of crunchiness and low sensorial porosity, while extrusion temperature and screw speed caused the opposite effect.