Enhanced physicochemical properties and riboflavin delivery ability of soy isolate protein/sugar beet pectin composite freeze-dried gels prepared by double crosslinking strategy

Improving the mechanical strength of protein freeze-dried gels materials has become a research priority in the field of nutrient delivery system development in recent years. In this study, double crosslinking freeze-dried gels were prepared by integrating laccase catalyzed sugar beet pectin (SBP) as a highly active filler molecule into the soybean isolate protein (SPI) thermally induced gel network, followed by freeze-drying. The double crosslinking freeze-dried gels were a porous material and the addition of SBP resulted in the formation of amorphous forms of freeze-dried gels with lower binding energy. The freeze-dried gels with 2.0 % SBP addition had the densest microstructure with the highest density (19.00 mg/cm3) and mechanical strength (180.43 +/- 15.27 KPa), and hydrogen bonding, N-H, C-N, and C--O bands were the most important factors to maintain the freeze-dried gels structure. As the concentration of sugar beet pectin increased, the release mechanism of riboflavin underwent a shift from a Fickian to a non-Fickian diffusion mechanism. In addition, the highest bioavailability of riboflavin was found in the freeze-dried gels spiked with 2.0 % SBP. These results will contribute to the development of double crosslinking freeze-dried gels carriers for targeted slow release of hydrophilic bioactive.