MATURITY & QUALITY
Maturity Indices
Firmness of 18 pounds-force, core clear of starch. Firmness (lbs-f) x soluble solids (%) x starch score (1 to 6 scale) should equal 250 at initiation of harvest.
Quality Indices
- Firmness, crispness, lack of mealiness
- Flavor, including soluble solids, titratable acidity and flavor volatiles.
- Freedom from defects such as bruising, decay, stem or blossom-end cracks, bitter pit, scald, internal browning, shrivel or watercore.
- Red skin color intensity and uniformity.
TEMPERATURE & CONTROLLED ATMOSPHERE (CA)
Optimum Temperature
0°C ± 1°C (32°F ± 2°F); Freezing temperature: -1.7°C (29°F)
Optimum Relative Humidity
90-95% RH
Rates of Respiration1
| Temperature | 0°C (32°F) | 5°C (41°F) | 10°C (50°F) | 20°C (68°F) |
| ml CO2/kg·hr | 2-5 | 3-7 | 5-10 | 12-2 |
To calculate heat production multiply ml CO2 /kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.
1Higher rates for riper apples.
Rates of Ethylene Production2
| Temperature | 0°C (32°F) | 5°C (41°F) | 10°C (50°F) | 20°C (68°F) |
| µl/ kg·hr | 1-10 | 2-20 | 5-40 | 20-12 |
2Higher rates for riper apples.
Responses to Ethylene
Ethylene stimulates ripening. Mixed results on the benefits of scrubbing ethylene from storage rooms, depending on harvest maturity and type of storage (air or CA).
Responses to Controlled Atmospheres (CA)
Fruit to be stored longer than 1 month benefit from CA storage in terms of retention of acidity and firmness and reduction of scald incidence and severity. CA storage potential is up to 10 months (vs. 6 months in air).
Recommended atmosphere: 1 to 2% O2 + 2 to 4% CO2
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