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Blanching & Hydro-Cooling: Enzyme Inactivation & Color Retention in IQF Lines

Process engineering guidelines covering hot-water and steam spiral blanching dwell times, peroxidase enzyme thermal inactivation kinetics, and two-stage chilled hydro-cooling to lock in crispness before IQF tunnel freezing.
Blanching & Hydro-Cooling: Enzyme Inactivation & Color Retention in IQF Lines

Thermal Inactivation Kinetics for Long-Term Frozen Produce Quality

Before vegetables enter IQF (Individually Quick Frozen) fluid bed tunnels, active endogenous enzymes must be inactivated. Without blanching, peroxidase and lipoxygenase will continue to break down flavor, texture, and bright chlorophyll pigments even at -18°C storage temperatures.

Q: Why is Two-Stage Hydro-Cooling crucial immediately after blanching?

Leaving blanched vegetables warm causes overcooking and leaching of vitamins. A two-stage hydro-cooler first drops the temperature from ~90°C to 20°C using ambient recirculated water, followed immediately by 0°C–2°C ice-water counter-current spray bringing produce core temperature below 5°C within 120 seconds, locking in crunchiness.

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