Cellulose fiber enhances the physical characteristics of extruded biodegradable cassava starch foams

An attempt was made to assess the influence of cellulose on the physical characteristics of cassava starch foams. Cassava starch was extruded with the inclusion of cellulose fibers with 2 different particle sizes (C1: 32 mu m and C2: 32-200 mu m) at 0, 5, and 10% with three different moisture contents (15, 17.5 and 20%) using a twin-screw extruder. The barrel temperature was fixed at 50, 100, 140 and 140 degrees C for all the experiments and the extruder screw speed was varied (150, 200, and 250 rpm), Cellulose fiber content and feed moisture content of the mixture had significant impact on the cassava starch foam properties. Addition of 5% C1 and C2 led to increased expansion ratio compared to the control (without the inclusion of any cellulose fiber). The greatest expansion ratio was observed in the cassava starch foam with 5% cellulose fiber, and at 15% mixture moisture content with 250 rpm screw speed. On the other hand, the expansion ratio decreased when cellulose fiber was increased up to 10%. Scanning electron microscope images at 5% cellulose fiber also showed that cellular structure of cassava starch foam was similar for the control. The water absorption index of cassava starch foams did not change significantly, while water solubility index of cassava starch foam with C2 was significantly different.