Effects of transglutaminase in product formulation on physico-textural properties of protein rich: Extruded snacks

Microbial transglutaminase (MTGase) is a widely used enzyme to modify the textural properties food proteins by causing the crosslinking of the protein matrix. In this research, we evaluate the effect of MTGase used in product formulation on the some physical and textural properties of a protein-rich extruded snacks. During product formulation the amount of pea protein and cheddar cheese added were maintained at 10% and 5% w/w respectively and the MTGase was 0.7% w/w, such that the final formulation moisture content was 16.5 ±1% (w.b.) Processing condition were kept constant at 58 g/min feed rate, 400 rpm screw speed, and die temperature of 140 °C. Selected physico-textural properties of the extrudates measured include: radial expansion ratio (ER), true and bulk density, porosity, water absorption index (WAI), water solubility index (WSI), hardness and fracturability. From the result, pure cornmeal containing snacks in comparison to other snacks with added ingredients (MTGase treated pea protein and/or MTGase treated cheddar cheese) showed the highest expansion ratio (2.9 ± 0.2) and porosity (92.7 ± 0.03%) as well as the least true density (1.3 ± 0.0 g/cm³), bulk density (0.1 ± 0.0 g/cm³), water solubility index (8.8 ± 1.4%), hardness (28.4 ± 8.2 N) and fracturability (29.9 ± 9.1 N). There was a significantly increase in the hardness, fracturability, and porosity of snacks of a similar formulation with or without MTGase (Formulations 4 and 5). Similarly, the presence of MTGase insignificantly affects the ER, true density, bulk density, WSI and WAI of these same snacks.