Curcumin-loaded soybean-dextran conjugate nanogels: Construction, characterization, and incorporation into orange juice beverage

Abstract

Although the health benefits of lipophilic bioactive compounds have received tremendous attention from both researchers and manufacturers, the practical application of these micronutrients in aqueous foods is still challenging due to their water insolubility and environmental instability. Therefore, curcumin (Cur) was selected to be encapsulated in soybean protein isolate-dextran conjugate-based nanogels (SDCNG) via the Maillard reaction combined with protein self-assembly to be incorporated into orange juice beverage (OJB) in this study. Cur-loaded SDCNG (Cur-SDCNG) prepared by adding Cur into the SDCNG solution exhibited an encapsulation efficiency of 89.10% ± 1.40% and a loading capacity of 17.11% ± 0.27%, enhanced 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical (•OH)-scavenging activities and ferrous reducing power, increased retention rate at both natural light and dark environment, and strengthened storage stability. Moreover, the loaded Cur showed a greater bioaccessibility (55.41% ± 0.71%) than free Cur (17.41% ± 1.04%). The OJB fortified with Cur by adding Cur-SDCNG exhibited an increasing color difference, particle size, polydispersity index (PDI), protein content, total soluble solid (TSS), and sensory score with the increasing Cur concentration. DPPH radical and •OH-scavenging activities and ferrous reducing power also further enhanced. The Cur-fortified OJB with an orange juice concentration of 30% exhibited improved quality attributes and satisfactory stability reflected by the increased TSS and sensory score, acceptable particle size, PDI, centrifugal sedimentation rate, and Cur retention rate under cold conditions. In conclusion, the findings confirmed the effectiveness of Cur encapsulation in SDCNG and the application feasibility of Cur-SDCNG in acidic beverages simultaneously fortified with lipophilic bioactive compounds and vegetable proteins.