Goose liver oil (GLO) microcapsules were prepared by konjac glucomannan (KGM) and soybean protein isolate (SPI) for the first time as wall materials. The GLO could be effectively encapsulated, with an encapsulation efficiency of 83.37%, when the ratio of KGM to SPI was 2.9:1, the concentration of the KGM-SPI composite gel layer was 6.28% and the ratio of the GLO to KGM-SPI composite gel layer was 1:6. Fourier transform infrared spectroscopy and X-ray diffraction methods showed electrostatic interactions between KGM and SPI molecules and the formation of hydrogen bonds between the GLO and KGM-SPI wall components. The results of scanning electron microscopy showed a smooth spherical surface morphology of the microcapsules with a dense surface and no cracks. The confocal laser scanning microscopy showed that the microcapsules were homogeneous inside and no coalescence occurred. The encapsulated GLO has a significantly higher thermal and oxidative stability compared to free GLO. In the in vitro digestion experiment, 85.2% of the microcapsules could travel through gastric juice, and 75.2% could be released in the intestinal region. These results suggested that microcapsules prepared by KGM-SPI might be used as a carrier for the controlled release of GLO and could microencapsulate various oil-soluble nutrients in food products.
Keywords: Fourier transform infrared spectroscopy; X-ray; goose liver oil; microcapsules; scanning electron microscopy.