گلابی آسیایی Asian Pear

Pear ‘Bartlett’

Maturity Indices

‘Bartlett’ pears attain best eating quality if picked at the mature-green stage and ripened off the tree since they become mealy if ripened on the tree.

California ‘Bartlett’ pear maturity standards utilize a combined flesh firmness/soluble solids content (SSC) index that is further modified by fruit size and skin color (if yellowish green, no firmness or SSC limits).

Minimum SSC

Fruit Diameter
Maximum flesh firmness (pounds-force)* 
2-3/8″ – 2-1/2″———–>2-1/2″

<10%

19.0——————–20.0

10%

20.0 ——————–21.0

11%

20.5 ——————–21.5

12%

21.0 ——————–22.0

13%

[No maximum]

*Penetration force with 8 mm (5/16 inch) tipM

Quality Indices

Fruit shape, size, and freedom from insect damage, mechanical injuries (impact, compression, and/or vibration bruising), decay, and other defects.

Sweet taste, pleasant aroma, and juicy, buttery texture are desired eating characteristics of ripe pears (flesh firmness range between 2 and 4 pounds-force).

Optimum Temperature

-1 to 0°C (30 to 32°F)

Optimum RH

90 to 95% Relative Humidity

Rates of Respiration

Temperature:

0°C (32°F)

2°C (36°F)

5°C (41°F)

20°C (68°F)

ml CO2/kg·hr:

2-3

4-5

6-8

15-35

* 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

Temperature:

-1 to 0°C (30 to 32°F)

5°C (41°F)

10°C (50°F)

20°C (68°F)

µl C2H4/kg·hr:

0.1-0.5

2-4

5-15

20-100

Responses to Ethylene

Mature-green ‘Bartlett’ pears can be treated with ethylene at harvest [100 ppm ethylene for 24 to 48 hours at 20 to 25°C (68 to 77°F)] to ensure uniform ripening within 4 to 6 days once fruit are warmed for ripening. The “at harvest” treatment is often referred to as “conditioning”. Fruit which has been cold stored for 3 weeks will ripen uniformly without ethylene conditioning. These pears can also be ripened in the presence of ethylene gas (100 ppm ethylene) at 18 to 22°C (64 to 72°F).

Responses to Controlled Atmospheres(CA)

Optimum CA 1 to 3% O2 + 0 to 3% CO2; for California-grown ‘Bartlett’ pears, 1.5 to 2% O2 + 1 to 5% CO2 are recommended for long-term storage of early- and mid- season harvested fruits. For late-season pears, CO2 should be kept below 1% because of the fruit’s greater sensitivity to CO2 injury (core and flesh browning).

CA conditions slow the rates of respiration, ethylene production, color change from green to yellow, and softening of pears. Scald development and decay incidence are suppressed under CA.

Storage potential of ‘Bartlett’ pears at -1 to 0°C (30 to 32°F) and 90-95% RH can be as long as 3 months in air and 6 months in CA.

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