ABSTRACT
Abstract: This research was undertaken to investigate the performance of a single-screw extruder for use in the mixing and homogenization of the composite of cassava starch (1000 g), glycerol (45%‒55% w/v), and zinc oxide nanoparticles (0%‒2% w/v) based on the mixing index and rate constant. The machine was designed such that it can accommodate two diameters (5 and 7 mm) in the breaker plate; the output/1000 g of the starch composite was determined at a resident time of 5 min over a period of 1 h machine operation. The research revealed that the composite containing 55% w/v glycerol, 1% w/v zinc nanoparticles and 5 mm diameter of the holes in the breaker plate has the highest mixing rate constant (k = 0.527). Decay trends were observed as the mixing index increases with an increase in the resident time in the range of 45%–55% w/v glycerol concentration and a decrease in the output per 1000 g of the starch composite through both the 5 and 7 mm diameters of the hole of the breaker plate. The optimum output of the machine, whose desirability function is closer to the optimization goal, gave 0.53/1000 g. The amount of unmixed composite was signicantly lower than the machine output and thus the single-screw extruder can be used to quantify and monitor mixing behaviour of starch composites in the food industry.
