MATURITY & QUALITY
Maturity Indices
Cantaloupes are harvested by maturity and not by size. Commercial maturity is ideally at the firm-ripe stage or “3/4 to full-slip” when a clear abscission (slip, separation) from the vine occurs with light pressure. Cantaloupes ripen after harvest but do not increase in sugar content (see below).
Cultivars vary in their external color at this stage of maturity and may retain a greenish cast. This skin color typically transitions from gray to dull green when immature, deep uniform green at maturity, and light yellow at full ripeness. A raised and well-rounded netting on the fruit surface is another indicator of proper commercial maturity.
Quality Indices
- Well-shaped nearly spherical and uniform in appearance
- Smooth stem end with no adhering peduncle (stem-attachment) which suggests premature harvest
- Absence of scars, sunburn or surface defects
- Firm with no evidence of bruising or excessive scuffing
- Appears heavy for size and has firm internal cavity without loose seeds or liquid accumulation.
U.S. grades are Fancy, No. 1, Commercial and No. 2. Distinction among grades is based predominantly on external appearances and measured soluble solids. Federal Grade Standards specify a minimum of 11% soluble solids for U.S. Fancy (“Very good internal quality”) and 9% soluble solids for U.S. 1 (“Good internal quality”). A calibrated refractometer, measuring °Brix, is accepted as the current standard for soluble solids measurements.
Sizing is based on count per 18.2 kg (40 lb.) container, most typically 9, 12, 15 and occasionally 18 or 23 melons per carton. An 18 to 45 count crate may also be used.
TEMPERATURE & CONTROLLED ATMOSPHERE (CA)
Optimum Temperature
2.2° – 5°C ( 36°- 41°F) Storage life is up to 21 days at 2.2°C (36°F) but sensory quality may be reduced. Typically 12-15 days of shelf life are attainable within the optimum range. Short term storage or transit temperatures below this range are used by some in the trade but may result in chilling injury after several days [for example,7 days or longer at temperatures below 2.2°C (36°F)].
Optimum Relative Humidity
90%-95%; High relative humidity is essential to maximize postharvest quality and prevent desiccation. Water loss through scuffed and damaged surface netting can be significant. Extended periods of higher humidity or condensation may encourage the growth of stem-scar and surface molds.
Rates of Respiration
| Temperature | 0°C | 5°C | 10°C | 15°C | 20°C | 25°C |
| (32°F) | (41°F) | (50°F) | (59°F) | (68°F) | (77°F) | |
| ml CO2/kg·hr | 2 – 3NR | 4 – 5 | 7 – 8 | 17 – 20 | 23 – 33 | 65 – 7 |
To calculate heat production multiply ml CO2/kg·h by 440 to get Btu/ton/ day or by 122 to get kcal/metric ton/day.
NR – not recommended for more than a few days due to chilling injury.
Rates of Ethylene Production
Intact fruit – 40 – 80µl/kg·h at 20°C (68°F)
Production Fresh-cut – 7-10µl/kg·h at 5°C (41°F)
Responses to Ethylene
Cantaloupes are moderately sensitive to exogenous ethylene and over-ripening may be a problem during distribution and short-term storage.
Responses to Controlled Atmospheres (CA)
Controlled atmosphere storage or shipping offer only moderate benefits for cantaloupes under most conditions. With extended transit times (14-21 Atmospheres (CA) days), cantaloupes are reported to benefit from delayed ripening, reduced respiration and associated sugar loss, and inhibition of surface molds and decay. Consensus atmospheres of 3% O2 and 10% CO2 at 3°C (37.4°F) has been demonstrated. Elevated CO2 at 10-20% is tolerated but will cause effervescence in the fruit flesh. This carbonated flavor is lost on transfer to air.
Low O2 (<1%) or high CO2 (> 20%) will cause impaired ripening, off-flavors and odors, and other condition defects.
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