Two types of pH-responsive genipin-crosslinked gelatin conjugates with high surface hydrophobicity for emulsion stabilization

The development of genipin modification methods has attracted much attention to improve the functional properties of proteins in the fields of food science . In this work, two types of pH-responsive genipin-crosslinked bovine bone gelatin conjugates with high surface hydrophobicity were developed for emulsion stabilization. One was genipin molecule-crosslinked gelatin conjugates prepared at acidic pH and the other was genipin macromer-crosslinked gelatin conjugates prepared at neutral and basic pH. The degrees of crosslinking increased with the increase of preparation pH. They increased with the increase of genipin-to-gelatin mass ratios at acidic pH, whereas decreased with the increase of genipin-to-gelatin mass ratios at neutral and basic pH. The surface hydrophobicity values, molecular weights, and emulsifying properties (creaming stability, emulsion activity index, and emulsion stability index) of the obtained conjugates increased with the increase of both preparation pH and genipin-to-gelatin mass ratios. This work provided useful knowledge to understand how the preparation parameters (preparation pH and genipin-to-gelatin mass ratio) and genipin structures (molecule and macromer) affect a protein's degrees of crosslinking, physicochemical properties, and emulsifying properties.