Enhancing texturization of upcycled durum wheat meal protein through pH adjustment and low-moisture extrusion optimization

Dry-fractionated, defatted durum wheat meal protein (DWMP) is an emerging upcycled food ingredient produced from by-products generated during semolina production. In our previous work, DWMP demonstrated potential for use in texturized vegetable protein (TVP) formulations. However, the resulting texture was suboptimal, suggesting the need for optimization of extrusion parameters. Therefore, the effects of three extrusion parameters (pH 6.9 and 7.5, screw speed 400 rpm and 600 rpm, and moisture content 28% and 32%) were evaluated during the production of TVP formulated with a pea protein isolate (PPI) and DWMP (75:25 w/w). Specifically, pH shifting was chosen as an extrusion variable having a significant impact on texture formation. Textural, physicochemical, and sensory properties of the extrudates were assessed using response surface methodology with a 2³ reduced factorial design. Higher screw speed increased the water-holding capacity (WHC) (on average, from 2.7 to 3.4 g H₂O/g) and specific volume (2.2→2.6 mL/g), while decreasing the water-solubility index (WSI) (14.1→11.9%) and hardness (4522→2763 g). Higher moisture content led to increased hardness (3255→4128 g) and decreased springiness (49.8→44.0%), and sensory perception of fibrousness (1.4→1.6 score). At higher pH, the WHC improved (2.5→3.4 g H2O/g), thereby leading to higher sensory moistness (5.4→6.3 score), and lower sensory hardness (2.8→2.1 score) of the extrudates. Overall, the findings demonstrate that extrusion conditions can be modulated to improve the physicochemical and sensory characteristics of the products, supporting the valorization of durum wheat milling side-streams in sustainable plant-based meat applications.