Collagen hydrolysates improve the efficiency of sodium alginate-encapsulated tea polyphenols in beads and the storage stability after commercial sterilization

This study showed that sodium alginates (SA)-based beads reinforced with collagen hydrolysates (CHs) significantly increased an encapsulation rate of tea polyphenols (TP) from 34.54 % to 85.06 % when the mass ratio of SA: CHs increased from1.5:0 to 1.5:0.5. And after the 30-day storage at 37 °C, the retention rate of TP in beads with CHs at the solutions with pH = 4.0 or pH = 7.0 increased from 61.10 % to 80.21 %, or from 67.72 % to 80.47 % after sterilization at 98 °C or 121 °C for 30 min, respectively. Also, the addition of CHs at 0.5 % resulted in a greater retention of the polyphenolic compositions values of TP determined by UPLC-Orbitrap-MS system. Additionally, the DPPH and ABTS+ free-radical scavenging capacities and ferric-reducing antioxidant power of beads with CHs after sterilization at 98 °C or 121 °C for 30 min were significantly higher than which without CHs. Physical phenomena based on ζ-potential, particle size, fluorescence, UV spectroscopy and confocal laser scanning microscope showed that tightly non-covalent complexes of CHs in combination to TP could be uniformly and stably distributed in the network of SA solution for encapsulating TP in SA-based beads. These findings provided suggestions for the co-encapsulation design and development of hydrophilic nutritive compounds based on CHs in SA-based beads.