Apple Red Delicious
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.
Apple Red Delicious Optimum Temperature
0°C ± 1°C (32°F ± 2°F); Freezing temperature: -1.7°C (29°F)
Apple Red Delicious Optimum Relative Humidity
90-95% RH
Rates of Respiration
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 | 12-25 |
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.
Higher rates for riper apples Red Delicious.
Rates of Ethylene Production
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 | 20-125 |
Higher 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% O 2 + 2 to 4% CO 2