Two protein ingredients, vital wheat gluten (WG) and hempseed protein concentrate (HPC), were extruded both individually and in combination, in a co-rotating twin-screw extruder to produce pilot-scale high-moisture meat analogues. To determine possible textural outcomes, the impact of the ratio between the input materials and operational settings was investigated. Seven different WG and HPC ratios were tested: 100% WG, 90:10 (WG:HPC), 70:30 (WG:HPC), 50:50 (WG:HPC), 30:70 (WG:HPC), 10:90 (WG:HPC), and 100% HPC. The target moisture content was varied between 57.5-67.5% for three different screw speeds (600, 700, and 800 rpm). A texture profile analysis, a puncture test, and two cutting tests were conducted on the extrudates. A principal component analysis was used to identify similarities in the data and determine how the protein ingredients and process parameters correlated to the extrudates' textural outcome. The study demonstrated that extrudates could be produced using up to 100% HPC. Higher HPC concentration and lower target moisture content generally led to increased hardness, chewiness, puncture resistance, and cutting forces. Force anisotropic balance ratio analysis suggested structural shifts between core and edge regions, where a lower target moisture content resulted in harder edges of the extrudates, increasing transversal cutting strength relative to longitudinal cutting strength. The ratio between WG and HPC had the most prominent effect on textural attributes, thereby underscoring the vital role of ingredient choice over process parameters for high-quality meat analogues. This is the first time where extrusion of hempseed protein as stand-alone crop has been demonstrated.
Ahlström et al. (Fri,) studied this question.