Lemon

MATURITY & QUALITY

Maturity Indices

A minimum juice content by volume of 28 or 30% depending on grade; color lemons picked at the dark-green stage have the longest postharvest life while those picked fully-yellow must be marketed more rapidly.

Quality Indices

• Yellow color intensity and uniformity
• Size
• Shape
• Smoothness; firmness
• Freedom from decay
• Freedom from defects including freezing damage, drying, mechanical damage, rind stains, red blotch, shriveling, and discoloration.

TEMPERATURE & CONTROLLED ATMOSPHERE (CA)

Optimum Temperature

12-14°C (54-57°F) depending on cultivar, maturity-ripeness stage at harvest, production area, and duration of storage and transport (can be up to 6 months).

Optimum Relative Humidity

90-95%

Rates of Respiration

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.

Rates of Ethylene Production

< 0.1 µl/kg·hr at 20°C (68°F)

Responses to Ethylene

If degreeing is desired, lemons can be treated with 1-10 ppm ethylene for 1-3 days at 20 to 25°C (68-77°F), but this exposure may accelerate deterioration rate and decay incidence

Responses to Controlled Atmospheres (CA)

CA of 5-10% O₂ and 0-10% CO₂ can delay senescence including loss of green color of lemons. Fungistatic CO₂ levels (10-15% are not used because they may induce off-flavors due to accumulation of fermentative volatiles, especially if O₂ levels are below 5%. Removal of ethylene from lemon storage facilities can reduce rate of senescence and decay incidence.