Water redistribution determined by time domain NMR explains rheological properties of dense fibrous protein blends at high temperature

Summary

Blends of different plant proteins can form excellent basis for meat analogues by subjecting those to shear and heating. We here want to obtain more information of the internal structure of pea protein-gluten and soy protein-gluten blends, by using the polymer blending law to explain rheological responses. For this polymer blending law the water distribution over the two phases is the blend was obtained with time domain 1H NMR measurements using the NMR measurements of individual protein phases and on the blend. By matching the relaxation rate (R2) of the individual phases with those of the blend, the water distribution over the two phases could be obtained. Water is preferentially taken up by the soy or pea protein phase leaving less water for gluten, which effect strongly changes the volume fractions of the phases. Rheological properties of the separate phases as function of their hydration resulted in higher apparent modulus for the wheat gluten phase, and a lower one for the pea and soy protein phase. From the results, it was concluded that both blends show signs of a bi-continuous morphology. The SPI-WG blend showed an intermediate value between bi-continuous and SPI continuous. PPI-WG at lower temperatures showed a bi-continuous structure, while at higher processing temperatures and time was probably WG continuous.