The physical properties of fermented Jaboticaba bagasse flour and some functional properties (expansion index and water solubility index) of the extrudates obtained from mixtures of rice and Jaboticaba bagasse flour were studied, which varied from 11.59 to 25.00% (bagasse/rice). The fermented Jaboticaba bagasse flour analyzed the particle size distribution, color, flavor and chemical composition. Some of these properties were compared with the non-fermented Jaboticaba bagasse and white rice. A single screw extruder with a compression rate of 1:3 fitted with a round die of 3 mm diameter was used at a variable screw speed (65.9 to 234.1 rpm) and feed rate at 5 kg/h. The temperature of the extruder heating zones 1 and 2 were kept constant at 50 and 100 °C, respectively and zone 3 varied from 99.54 to 200.46 °C. Surface response methodology was used to show the effect of bagasse concentration and the parameters (temperature and screw speed). The results showed that fermented jaboticaba bagasse is a good source of fiber, proteins and minerals and is made up of fine particles with the aroma of the fruit and slight salty bitter taste. Radial expansion increased as the screw speed increased and decreased as the jaboticaba bagasse flour increased showing a quadratic effect as the temperature increased. Water solubility index increased as the screw speed increased and reduced as the temperature decreased. High expansion index (3.26) and water solubility (17.55%) were reached for the formulation with 10% fermented jaboticaba bagasse at 240 rpm screw speed and at 130 and 100 °C temperatures, respectively. Fermented jaboticaba bagasse flour can be incorporated into rice flour to produce pre-gelatinized flour if appropriate operational conditions are used.
thermoplastic extrusion; rice flour; jabuticaba; response surface methodology; agroindustry by-products
