Strategies for Enhancing Expansion in Starch-Based Microcellular Foams Produced by Supercritical Fluid Extrusion

Supercritical fluid extrusion is usually a recent technical development for production of extended starch-based foams where formation of a microcellular structure is in fact achieved by injection of supercritical CO2 into the melt. The high effective diffusivity of CO2 in the porous matrix favors escape of the gas to the surroundings, reducing the amount designed for diffusion in to the bubbles, posing an important challenge thus. This research utilized two methods to address this problem: increasing the nucleation charge and thus the ultimate bubble density in the foam, and minimizing the melt temp. The former was achieved by decreasing the nozzle diameter to be able to achieve a higher pressure drop rate because the starch-CO2 melt flows through the nozzle. The next procedure was evaluated by introducing a cooling zone before the entry of the melt into the nozzle. If you cherished this article and you would like to receive more info with regards to plastic extruder nicely visit the web-site. Bubble density raised more than fourfold when the nozzle radius was decreased from 3.00 to 1 1.50 mm. A higher bubble density resulted in a larger barrier or level of resistance to diffusion of CO2 to the surroundings, and increased expansion ratio by as substantially as 160%. Cooling of the melt resulted in a reduction in diffusion coefficient of CO2 in the starch melt, and therefore reduced CO2 reduction to the environment. The growth ratio increased by 34% as the melt heat range reduced from 60 to 40°C. The above-mentioned tactics can be useful in enhancing and controlling expansion, which determines the textural attributes of the expanded food product ultimately.