Effects of Different Zn2+ Concentrations and High Hydrostatic Pressures (HHP) on Chlorophyll Stability.

This study provides a new idea for improving chlorophyll stability and color quality of green leafy vegetables by Zn2+ synergistic HHP. Zn-chlorophyll was prepared with zinc acetate and chlorophyll under HHP treatment. The effects of different zinc acetate concentrations and pressures on chlorophyll color, antioxidant activity, Zn2+ replacement rate, structure, and thermal stability were analyzed. Results showed with increased zinc acetate concentration and pressure, -a* value, antioxidant activity, and Zn2+ replacement rate of samples gradually increased. However, FTIR indicated the structure did not change. HHP fluorescence online analysis showed fluorescence intensity of samples decreased with zinc acetate concentration and pressure increasing. With zinc acetate 10 mg/100 mL and HHP 500 MPa, the highest -a* value (5.19), antioxidant activity (ABTS, DPPH, and FRAP were 37.03 g ACE/100 g, 25.95 g ACE/100 g, 65.43 g TE/100 g DW, respectively), and Zn2+ replacement rate (42.34%) were obtained. Thermal stability of Zn-chlorophyll obtained by synergistic effect was improved significantly.