Fruit Produce Facts English
Recommendations for Maintaining Postharvest Quality
Maturity & Quality
The burrs begin to dehisce between mid September and early October (depending on the cultivar and production area) shedding the nuts. Chestnuts should be picked up daily during the harvest season to minimize fungal infection and growth (if infection occurred while the nuts are still on the tree) and loss of quality due to excessive drying and/or sunburn. Use of a tarp below the tree can reduce contamination of the nuts due to direct contact with the soil. Alternatively, a mechanical shake-catch harvester can be used. Following harvest the remaining burrs should be removed. Fresh chestnuts contain 40 to 60% moisture and should be handled with care to avoid mechanical damage.
Maturity & Quality Photos
Temperature & Controlled Atmosphere
-1 to 0°C (30 to 32°F); highest freezing point is -2°C (28°F) for European chestnut and –5°C (22°F) for Chinese chestnut; prompt cooling to 0°C (32°F) is strongly recommended to stop decay development and preserve quality.
Optimum Relative Humidity
90–95%; packaging in microperforated plastic film is highly recommended to minimize water loss from fresh chestnuts.
Rates of Respiration
2.5-3.5 ml CO2/kg·hr at 0°C (32°F)
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
Preharvest or postharvest exposure of burrs to 50-100 ppm ethylene gas or 500-1000 ppm ethephon (ethylene-releasing liquid) accelerates dehiscence. There are no reported effects of ethylene on the nuts.
Responses to Controlled Atmospheres (CA)
An initial exposure to 40-50% CO2 for 5-7 days at 0°C (32°F) followed by storage in a CA of 2-3% O2 + 15-20% CO2 is very effective in preventing mold growth, sprouting, and other quality deterioration factors. Exposure of fresh chestnuts to <1% O2 results in fermentative metabolism and off-flavor development. Under optimal temperature of –1 to 0°C (30 to 32°F), relative humidity (90-95%), and CA (2-3% O2 + 15-20% CO2), fresh chestnuts can be stored for up to 4 months.
Physiological and Physical Disorders
Sprouting results from exposure to high temperature and humidity and can be avoided by using optimal storage conditions.
Several fungi (including Alternaria spp, Aspergillus niger, Botrytis cinerea, Fusarium spp, Penicillium spp, and Phomopsis castanea) can infect chestnuts and result in significant postharvest losses in quality and marketability. Control strategies include the following:
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.