Date

MATURITY & QUALITY

Maturity Indices

A small quantity of dates is harvested at the “Khalal” stage (partially-ripe) when they are yellow or red (depending on cultivar), but many consumers find them astringent (high tannin content). Most dates are harvested at the fully-ripe “Rutab” and “Tamar” stages, when they have much greater levels of sugars, lower moisture and tannin content, and softer than the “Khalal” stage dates.

Quality Indices

• Fruit size, color, texture, cleanliness
• Freedom from defects (such as sunburn, insect damage
• Sugar migration to fruit surface, and fermentation) and decay-causing pathogens
• Sweetness: Sucrose is the main sugar in some cultivars while reducing sugars are predominant in others; total sugars represent about 50% (fresh wt basis) or 75% (dry wt basis).

TEMPERATURE & CONTROLLED ATMOSPHERE (CA)

Optimum Temperature

• 0°C (32°F) for 6-12 months, depending on cultivar (semi-soft dates, such as “Deglet Noor” and Halawy”, have longer storage-life than soft dates, such as “Medjool” and “Barhi”).
• -18°C (0°F) for longer storage durations. [Freezing temperature is -15.7°C (3.7°F)]

Optimum Relative Humidity

70-75%; at higher relative humidities, dates will absorb moisture from the room air unless they are packaged in moisture-proof containers.

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

<0.5 microliter/kg·hr for “Khalal” stage dates; <0.1 microliter/kg·hr for “Rutab” and “Tamar” stage dates kept at 20°C (68°F).

Responses to Ethylene

Ripe dates are not influenced by ethylene but can readily absorb the aroma of other products. Thus, dates should not be stored with garlic, onion, potato, or other commodities with strong odor.

Responses to Controlled Atmosphere (CA)

Packaging in nitrogen (to exclude oxygen) reduces darkening of dates and prevents insect infestation.