Complex coacervation of low methoxy pectin with three types of gelatins for the encapsulation of fish oil.

Herein, the complex coacervation of low methoxy pectin (LMP) with three types of gelatins was explored to encapsulate fish oil. The fish oil@gelatin-LMP complex coacervates with good precipitation separation could be obtained at low gelatin concentrations (Fish gelatin, FG: 10-80 mg/mL; porcine skin gelatin, PSG: 10-40 mg/mL; bovine skin gelatin, BSG: 10-80 mg/mL), high gelatin: fish oil mass ratios (4:1-1:1), appropriate gelatin: LMP mass ratios (3:1-12:1 for FG and PSG, 6:1 for BSG), and appropriate pH (FG: 4.90-5.50; PSG: 4.80-5.40; BSG: 4.10-4.50). FG induced similar loading ability, lower encapsulation ability, and comparable peroxide values to the mammalian gelatins. FG induced higher or similar free fatty acid released percentages to mammalian gelatins in the in vitro gastrointestinal model at low gelatin concentrations (10-40 mg/mL). These results provided useful information to understand the protein-polysaccharide complex coacervation to encapsulate oil-based bioactive substances.

Effects of polyphenol and gelatin types on the physicochemical properties and emulsion stabilization of polyphenol-crosslinked gelatin conjugates.

Herein, six types of polyphenol-crosslinked gelatin conjugates (PGCs) with ≥ two gelatin molecules were prepared using a covalent crosslinking method with two types of polyphenols (tannic acid and caffeic acid) and three types of gelatins (bovine bone gelatin, cold water fish skin gelatin, and porcine skin gelatin) for the emulsion stabilization. The structural and functional properties of the PGCs were dependent on both polyphenol and gelatin types. The storage stability of the conjugate-stabilized emulsions was dependent on the polyphenol crosslinking, NaCl addition, and heating pretreatment. In particular, NaCl addition promoted the liquid-gel transition of the emulsions: 0.2 mol/L > 0.1 mol/L > 0.0 mol/L. Moreover, NaCl addition also increased the creaming stability of the emulsions stabilized by PGCs except tannic acid-crosslinked bovine bone gelatin conjugate. All the results provided useful knowledge on the effects of molecular modification and physical processing on the properties of gelatins.