Fruit Produce Facts English
Recommendations for Maintaining Postharvest Quality
Maturity & Quality
Maturity & Quality Photos
Temperature & Controlled Atmosphere
0 ± 1°C (32 ± 2°F)
Freezing point: -1.5°C (29°F); may vary depending on soluble solids content.
Optimum Relative Humidity
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
Responses to Ethylene
Exposure of climacteric cultivars to >1 ppm ethylene accelerates loss of green color and slightly increases softening at 20°C (68°F). The effects of ethylene at 0°C (32°F) are minimal.
Responses to Controlled Atmospheres (CA)
Temperature & Controlled Atmosphere Photos
Physiological and Physical Disorders
Low oxygen injury. (Discolored surface depressions) Resulted from exposing '20th Century' pears to 1% O2 for 4 months at 0°C (32°F) and from exposing 'Ya Li' and 'Tsu Li' pears to 1% O2 for 2 months, 2% O2 for 4 months, or 3% O2 for 6 months at 0°C (32°F).
High carbon dioxide injury. (Core or medial flesh browning; cavities may develop in severe cases as a result of desiccation of dead tissue) 'Ya Li' pears exhibited CO2 injury after exposure to 5% CO2 for 6 weeks at 0°C (32°F).
Flesh spot decay. (FSD) Symptoms (brown spots and/or cavities in the flesh) appear along and around the vascular bundles when severe but are not visible externally. FSD affects mainly Nijisseiki, Shinseiki, and Hosui Japanese pear cultivars and is usually more pronounced toward the stem end of the fruit, but can occur all the way down to the calyx. FSD incidence and severity can be reduced by avoiding harvesting over-mature fruits.
Watercore. Symptoms (glassy diffuse water soaked areas in the flesh; affected areas may taste sweet and may turn slightly brown) occur on some cultivars (such as Nijisseiki, Shinseiki, and Hosui) grown under conditions favoring vigorous tree growth. Avoid harvesting over-mature fruits to reduce watercore incidence and severity.
Internal browning. Symptoms (brown discoloration in the core, carpels, and flesh areas) appear mainly in Chinese pear cultivars (such as Tsu Li, Ya Li, Seuri, and Dan Be). This disorder can be avoided if the fruits are picked when still green with a few fruits at the top of the tree showing some light yellowish green color (after about 180 days after full bloom).
[For more information, see our publication "Fruit Ripening and Ethylene Management", available for purchase using our Publication order form.]
Use of Materials
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The information in this fact sheet represents our best understanding of the current state of knowledge at the time of the latest update, and does not represent an exhaustive review of all research results. Links to any of these UC Postharvest Technology Center pages are permitted, but no endorsement of the linking site or products mentioned in the linking page is intended or implied by such a link.
How to Cite
Author(s) names. Initial publication or update date (located at the top). Title. Link to the specific Produce Fact Sheet webpage (Accessed date)
Example: Cantwell, M. and T. Suslow. 2002. Lettuce, Crisphead: Recommendations for Maintaining Postharvest Quality.