POST-HARVEST COOLING GUIDE
Prompt removal of field heat can slow respiration and help preserve fresh-produce quality. Use this guide to compare precooling methods, holding conditions, humidity, packaging and sensitivity for high-value Southeast commodities—then confirm the final target for your cultivar, maturity, package, market and storage duration.
Blueberries
Holding reference: 32°F at 90–95% RH. Primary method: forced-air cooling. Design note: cool promptly, align package vents, seal the pallet tunnel and verify pulp temperature rather than relying only on room-air temperature.
Watermelons
Storage: 50-60°F at 90% RH. Primary Method: Room Cooling. Critical Note: Do not drop below 45°F; cold stress leads to loss of crispness and muted color.
Peaches
Holding reference: 31–32°F at 90–95% RH. Primary method: forced-air cooling is commonly used for packed peaches. Design note: cooling air, package vents, airflow and pulp-temperature checks must be coordinated; cultivar and intended storage duration affect the final recommendation.
Bell Peppers
Storage: 45-50°F at 90-95% RH. Primary Method: Forced-Air. Critical Note: Highly prone to dehydration; chilling damage appears as surface pitting and rot.
Broccoli
Holding reference: 32°F at 95–100% RH. Precooling may use forced air or icing where the commodity, package, drainage and sanitation program are compatible. Confirm the handling plan before specifying ice equipment.
Sweet Corn
Storage: 32°F at 95-98% RH. Primary Method: Hydrocooling. Critical Note: Immediate cooling is required to stop sugar from converting into tasteless starch.
SELECTING OPTIMAL COOLING SYSTEMS
Forced-Air Systems
This method utilizes pressure differentials to pull cold air through packed pallets. It is the gold standard for berries and peppers because it offers much faster results than room cooling.
Hydrocooling
Chilled water can remove heat rapidly when it reaches the product uniformly. Hydrocooling is appropriate only when the commodity and package tolerate wetting, and the design includes filtration, sanitation, water-temperature control, drainage and sufficient refrigeration load.
Icing Methods
Injecting slush or crushed ice into containers ensures a constant 32°F environment. High-respiration crops like corn rely on this method to maintain quality during heavy transport.
TECHNICAL COMMODITY SPECIFICATIONS
Commodity
Temp (°F)
RH (%)
Cooling System
Risk Factor
Blueberries
32
90-95
Forced-Air
Botrytis/Mold
Peaches
31-32
90-95
Hydro/Forced
Internal Breakdown
5 STAR REFRIGERATION – Cooling the Southeast, One Commodity at a Time. We provide specialized engineering for agricultural facilities, ensuring your specific crop requirements are met with precision climate control and custom-designed cooling technology.
The 7/8 Cooling Rule
The 7/8 cooling point is reached after removing 87.5% of the temperature difference between the product at loading and the cooling medium. It is a useful performance benchmark for cooling time, not a universal final storage specification or a guarantee of quality.
Example: If produce starts at 80°F and the cooling medium is 32°F, the 7/8 cooling time is reached when the product core temperature hits 38°F.
Storage recommendations vary by cultivar, maturity, packaging, market and intended storage duration. Confirm final requirements with current Extension guidance and a qualified refrigeration professional. Sources & Further Reading: UGA Cooperative Extension commodity publications; NC State Extension’s Introduction to the Postharvest Engineering for Fresh Fruits and Vegetables; UF/IFAS HS1270. Last reviewed: August 2026.