Modulating fracture properties of mixed protein systems

• Fracture properties of rarely studied SPI/gelatine gels were studied.
• When mixed, SPI and gelatine form independent gels.
• Fracture stress of mixed gels is determined by the stronger of the two interpenetrating gels.
• Wide variety in fracture properties can be created with mixed protein systems.

To design foods with desired textures it is important to understand structure build-up and breakdown. One can obtain a wide range of structures using mixtures of different structuring ingredients such as for example protein mixtures. Mixed soy protein isolate (SPI)/gelatine gels were analyzed for their linear rheological properties, fracture properties and microstructure. The two ingredients were found to form independent networks despite changes in the SPI microstructure, which were attributed to micro phase separation. It is shown that mixing of SPI and gelatine allows to arrive at a large variety of fracture properties. This provides opportunities for tailoring textures in foods using mixed independent gel networks. The fracture stress of mixed gels corresponded to the fracture stress of the strongest of the two gels. At constant fracture stress, increasing Young's modulus of the mixed independent gels resulted in reduced fracture strain.

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