Persimmon

MATURITY & QUALITY

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

TEMPERATURE & CONTROLLED ATMOSPHERE (CA)

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

90-95%

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.

Responses 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.