Tailoring anisotropy and tenderness in high-moisture extruded plant protein structures by in-line microfoaming

Meat alternatives are a sustainable food option increasingly becoming a regular part of many consumers' diets. One major challenge in developing plant-based meat alternatives is replicating the diverse range of textural characteristics found across various conventional meat products. This study investigated the impact of nitrogen gas volumetric flow rate (0, 5, 10, 20, 40 ml/min) and gas injection position (barrel section 3 (midsection) and barrel section 4 (terminal section)) on the mechanical anisotropy, textural properties, and microstructure of high moisture extrudates by modifying the porosity. The results showed that gas incorporation creates porous structures with mean pore sizes ranging from 18.18 to 73.94 μm and from 21.01 to 77.30 μm in barrel section 3 and 4, respectively. As the gas injection volume increases from 0 to 40 ml/min, the density of the extrudates was reduced up to 14.82 % while enhancing its lightness and visual fibrous structure. Moreover, the incorporated gas lowered Warner-Bratzler shear force, hardness, and chewiness in both barrel section 3 and 4 and consequently increased the tenderness of the extrudates. Similarly, the elastic anisotropy index increased from 1.35 for the control with no gas injection to 1.70 for samples with gas injection at 5 ml/min in barrel section 3. Dynamic mechanical analysis revealed a decrease in extensional storage and loss modulus as the gas flow rate increased. These findings reveal that modifying the porous structure through gas-assisted extrusion can effectively tailor the structural and textural attributes of high-moisture extrudates and indicate the potential towards more desirable product characteristics.