Multihole nozzle-mediated high-moisture extrusion of soy proteins into fiber-rich structures

Abstract

High-moisture extrusion (HME) is an appealing strategy for the production of textured vegetable proteins (TVP) with meat-like structures. However, the processing parameters and formulation have a limited influence on the quality characteristics of the final HME-TVP. Therefore, we improved the component design of the cooling die, which is critical to protein texturisation, to yield the desired extruded products. In the present study, a multihole nozzle set was specifically designed to regulate protein texturisation in the cooling die. The fibrous structure, texture, and in vitro digestibility of the nozzle-produced HME-TVP were investigated at different cooling temperatures. The results showed that the integration of a multihole nozzle in the cooling die greatly improved protein texturisation. In contrast to the parabolic fiber distribution of conventionally extruded proteins, the resulting HME-TVP featured a meat-like structure with parallel and straight fibers. Furthermore, nozzle-produced HME-TVP at 40 °C exhibited excellent freeze-thaw stability and rehydration capacity. Significant structural changes in HME-TVP had little impact on protein digestibility unless the cooling die temperature was below 40 °C. These findings provide a valuable technical path to improve the quality of plant-based meat analogue products.