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Recommendations for Maintaining Postharvest Quality

Carlos H. Crisosto, Elizabeth J. Mitcham, and Adel A. Kader Department of Pomology, University of California, Davis, CA 95616

Maturity Indices
Minimum maturity is based on skin color change from green to orange or reddish-orange (Hachiya) or to yellowish-green or yellow (Fuyu, California Fuyu, Jiro).

Quality Indices

  • Yellow to orange color
  • Medium to large size
  • Firm (penetration force, using an 8-mm tip, is above 5 lb-force for ‘Fuyu’ and similar cultivars)
  • Freedom from growth cracks, mechanical injuries, and decay
  • Soluble solids of 21-23% in ‘Hachiya’ and 18-20% in ‘Fuyu’ and similar non-astringent cultivars
  • No astringency (tannin content)
  • Nutritive value: good source of carotenoids, vitamin A, vitamin C, and dietary fiber

Optimum Temperature
0 ± 1°C (32 ± 2°F)

Freezing point. -2°C (28°F); may vary depending on soluble solids content.

Chilling injury. ‘Fuyu’ and similar non-astringent cultivars are chilling- sensitive at temperatures between 5°C and 15°C (41°F and 59°F) and will exhibit flesh browning and softening. Exposure to ethylene aggravates chilling injury at these temperatures.

Optimum Relative Humidity

Rates of Respiration
2-4 ml CO2/kg·hr at 0°C (32°F)

10-12 ml CO2/kg·hr at 20°C (68°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
>0.1 µl/kg·hr at 0°C (32°F) 0.1-0.5 µl/kg·hr at 20°C (68°F)

Responses to Ethylene
Persimmons are very sensitive to ethylene action. Exposure to 1 ppm and 10 ppm ethylene at 20°C (68°F) accelerates softening to less than 4 lb – force (limit of marketability) after 6 and 2 days, respectively. Thus, ethylene removal and/or exclusion from transport and storage facilities is highly recommended.

Removal of Astringency from ‘Hachiya’ Persimmons
Ethylene (10 ppm) at 20°C (68°F) can be used to remove astringency but the excessive softening that results would make it very difficult to market the persimmons. Exposure to air enriched with 80% CO2 for 24 hours at 20°C (68°F) is effective in removing astringency while maintaining firmness.

Responces to Controlled Atmospheres(CA)

  • Low oxygen (3- 5%) delays ripening.
  • Carbon dioxide at 5- 8% helps retain firmness and can reduce chilling injury symptoms on ‘Fuyu’ and similar cultivars.
  • Postharvest life under optimum temperature and relative humidity in ethylene- free air can be up to 3 months vs. 5 months in optimum, ethylene- free CA (3-5% O2 + 5-8% CO2)conditions.

Physiological Disorders

  • Exposure to oxygen levels below 3% during storage for longer than one month can result in failure of persimmons to ripen and in off- flavors.
  • Exposure to carbon dioxide levels above 10% during storage for longer than one month can cause brown discoloration of the flesh and off- flavors.

Postharvest Technology Research and Information Center
Department of Pomology
University of California
One Shields Ave., Davis, CA 95616-8683
Send comments and questions to Postharvest Technology Research and Information Center
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Produce/ProduceFacts/Fruit/persimmon.html updated July 5, 2000

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