Gas-assisted high-moisture extrusion of soy-based meat analogues: Impacts of nitrogen pressure and cooling die temperature on density, texture and microstructure

This study explored the potential of a novel gas-assisted high-moisture extrusion cooking technique to improve the physical quality of meat analogues. Extrusion was performed as a full factorial design at three long cooling die temperatures (DT) (35, 50 and 65 degrees C) and three nitrogen gas injection pressures (GP) (0, 1 and 2.5 bar). The lowest meat analogue density was observed for the meat analogues produced at the lowest DT and highest GP combination. At the lowest DT, gas injection substantially decreased meat analogue hardness, chewiness and gumminess. X-ray microtomography analyses for meat analogues produced at 2.5 bar gas injection pressure revealed that DT significantly affected bubble sizes with larger and more diverse bubbles in the meat analogues produced at the lowest DT. These microstructural variations indicate that gas-assisted high-moisture extrusion cooking can be fine-tuned to improve the texture and, thus, sensory properties of meat analogues. Industrial relevance: High-moisture extrusion cooking is widely used for industrial-scale production of plant-based meat analogues. Manufacturing meat analogues with desired hardness and chewiness without detrimental effects on other characteristics such as color and degree of texturization is still quite challenging using conventional high-moisture extrusion cooking. Gas-assisted high-moisture extrusion cooking, when fine-tuned, has great potential in manipulating end-product texture and color without negatively impacting the degree of protein texturization.