Cultivars:
Topred, Starking, Starkrimson, Early Red One, Red Chief, Oregon Spur, Jeromine, Romeo, African Carmine Harvest Maturity:
DALRRD Minimum Standards:
o Minimum starch breakdown: 8%
o Minimum pressure: 5.9kg
o Minimum pip colour: 2/3 brown
• Industry Optimum Harvest Maturity (for long term CA storage): o Minimum starch breakdown – 15-30%
o Minimum pressure – 7.2kg
▪ African Carmine – 6.8kg
o Minimum TSS – 12%
o Minimum pip colour – 2/3 brown
• Harvesting red cultivars overmature and attempting to store for long-term CA is the biggest issue with regards to quality problems.
• Post-optimum fruit should not be stored for long-term CA.
Harvesting Process:
• Red cultivars do bruise, so watch out for rough handling and emptying of picking bags.
• Torn-out stems can also become a problem when there is rough handling.
• Leaving sunburn in orchard run bins should be considered if fruit are to be stored, because it can lead to scald in CA.
• Cover the bins with wet blankets during transport from the orchard to bin off-loading area.
• Deliver fruit from orchard to packhouse on the same day.
Fruit receiving:
• Drench incoming fruit
o Chlorine drench @ 100ppm.
o Test chlorine concentration every 200 bins to ensure effective treatment.
Pre-cooling:
• Red cultivars are to be cooled to a core temperature of -0,5°C within 48 hours of harvest and held at that temperature during storage.
• Place fruit under refrigeration within 24 hours from start of harvesting.
• Every coldroom has a maximum cooling capacity, and that should be adhered to.
o If the coldroom was designed to effectively cool down 200 bins per day, don’t overload it.
o Rather switch on an extra coldroom to have enough capacity for cooling incoming fruit effectively.
o Loadshedding will have a negative impact on the cooling capacity.
CA:
• Loading should not take longer than 7 days, during which time effective cooling must take place (see pre-cooling above).
• Relative Humidity: 90-95%
• Storage regime for red apples should be as indicated in the CA Manual (January 2019).
| Cultivar | O₂ (%) | CO₂ (%) | Temp (°C) | Storage (months) | Treatment |
|---|---|---|---|---|---|
| Topred | Optimum: 1.5 | 2.5 or 1.5 | -0.5 | 9 | SF / DCA |
| Maximum: 2.0 | 3.0 | 0.0 | |||
| Minimum: 1.0 | 1.0 | -0.5 | |||
| African Carmine | Optimum: 1.5 | 1.5 | -0.5 | 7 | SF / DCA |
| Maximum: 2.0 | 3.0 | 0.0 | |||
| Minimum: 1.0 | 1.0 | -0.5 |
• Nitrogen flushing: attain a gas regime of 3% O2 + 1.5% CO2 within 48 hours of sealing the room. The CO2 concentration must not exceed 2.5% during the pull-down period.
• Nitrogen generator: attain a gas regime of 3% O2 + 3% CO2 within 48 hours of sealing the room. The CO2 concentration must not exceed 2.5% during the pull-down period.
• The following gas regimes should be reached within 7 days of sealing the room (i.e. within 14 days from start of harvesting):
o 3.0% O2, 1.5% CO2
o CO2 levels should never exceed 2.5% to prevent possible damage to the fruit.
Packing:
• When packing wet, maintain a chlorine concentration of 100ppm in the flumes.
• Generally, pack in 20 micron bags.
Re-cooling:
• Forced air cooling of all pallets (including local) is important.
Final fruit temperature of -0.5° should be reached within 72 hours after packing.
Load out:
• Container temperature set point at -0.5°C, vents open