Soy protein isolate (SPI) was isolated from Indonesian soybean var. Grobogan and converted into protein nanofibrils. Their functionalities as a food thickener and building blocks for microcapsules were investigated and compared with those of commercial whey protein isolate (WPI). The isolation yield was about 58% with SPI’s protein content of about 90% on dry basis. Long and branched SPI fibrils with a few nanometers of diameter were obtained by heating SPI suspension at pH 2.0. The solution of SPI fibrils was shear thinning with much higher viscosity than the unheated SPI which was Newtonian. The fibrils showed a good potential as building blocks of microcapsules prepared by layer-by-layer adsorption method, which were similar to WPI fibrils.
Keywords: Soybean var. Grobogan, soy protein isolate, nanofibrils, viscosity and microcapsules