Modeling of bubble growth dynamics and nonisothermal expansion in starch‐based foams during extrusion

Abstract

A mathematical model was developed to describe expansion phenomena in starch-based foams during extrusion. The model was divided into three parts to describe the microbubble growth dynamics, to couple bubble growth with extrudate expansion, and to describe the macrotransport phenomena in the extrudate, respectively. The differential equations involved in the model were solved by finite element schemes. For validating the model, the predicted radius, density, and residual moisture of final extrudate were compared with experimental data. Standard deviations between the predicted and experimental radius, density, and residual moisture of final extrudates were 16.7%, 11.2%, and 39.3%, respectively. The model was used to predict the profiles of downstream velocity, expansion ratio, moisture content, and temperature of extrudate during expansion.

Antioxidant potential and quality characteristics of vegetable-enriched corn-based extruded snacks

“…The severity of thermal treatment affects the macromolecular degradation during extrusion cooking, which influences the degree of cooking. Generally, the degree of cooking can affect the pore size formation during extrusion cooking and, consequently the degree of expansion of starch based extrudates (Wang et al 2005). In contrast, the sensory diameter of olive paste extrudates affected significantly by material ratio and screw rotation speed (p<0.01).…”

“…5 and 6). The increased levels of temperature favor the bubble formation (Wang et al 2005). Furthermore, increasing the feed moisture content leads to the formation of more rigid structures with increased apparent density, resulting in decreased number of open cells in extrudates cellular matrix (Lazou and Krokida 2010b).…”

Twin screw extrusion of kodo millet-chickpea blend: process parameter optimization, physico-chemical and functional properties

“…Increase in screw speed might have caused good puffing of the starchrich feed into hot melts which can be expanded as they emerge from the die, thus forming bubbles and expand within the melt to form continuous foam (Guy 2001). High temperature results in increased bubble radius simultaneously causing increase in matrix radius and decrease in shell wall thickness (Wang et al 2005). This gives the extrudate a brittle structure needed for a good snack which is measured as the extrudate fractures when compression force is applied.…”

Application of extrusion-cooking technique for foamed starch-based materials

“…Starch-based foamed materials are lightweight and can be used successfully in packaging [11][12][13][14]. However biodegradable foamed materials, based on natural raw materials, are characterized by brittleness and poor water resistance.…”