Understanding fiber formation in a concentrated soy protein isolate - Pectin blend

Concentrated blends of pectin in soy protein, subjected to simple shear flow while heated form solid, fibrous materials that are a basis for meat analogues. The commonly accepted ‘rule of mixing’ based on the cross-sectional area of a weak dispersed phase was used to predict mechanical anisotropy of the material. Experimentally, two different dispersed phases were observed in the continuous soy protein matrix; air and pectin. An optimum in shape anisotropy of the air and pectin droplets, and mechanical anisotropy was found for a shear rate of 39 s−1. At higher shear rates, air was expelled and break-up of pectin droplets was found, resulting in materials with hardly any mechanical anisotropy. There was discrepancy between the modeled and experimental data when using the same mass fraction and volume fraction of pectin, whereas the model fitted better when assuming that the pectin phase absorbs more water relatively to the soy phase.