کرفس celery

celery

Maturity Indices

Celery is harvested when the overall field reaches the desired marketable size and before the outer petioles develop “pithiness” (See Pith Breakdown below). Celery has very uniform crop growth and fields are harvested only once and stalks are packed by size after trimming outer petioles and leaves.

Quality Indices

High quality celery consists of stalks which are well formed, have thick petioles, are compact (not significantly bowed or bulging), have minimal petiole twisting, and have a light green and fresh appearance. Additional quality indices are stalk and midrib length, freedom from defects such as blackheart, pithy petioles, seedstalks, cracks or splits, and freedom from insect damage and decay.

U.S. Grades : Extra No. 1; No. 1; No. 2 ( Grade Standards established 1957)
Celery may be sold as “Unclassified” to designate a lot which has not been graded within U.S. standards.

Optimum Temperature

0°C (32°F)

At optimum conditions, celery should have good quality after storage up to 5 to 7 weeks. Commonly, celery is rapidly pre-cooled and then stored at 0 to 2°C (32 to 36°F) if storage is intended to be less than one month storing celery at 5°C (41°F) is not recommended for more than 2 weeks. To maintain good visual and sensory quality. Some continued growth of inner stalks will occur postharvest at temperatures >0°C (32°F) .

Optimum Relative Humidity

98-100% R.H.

Rates of Respiration

Temperature

0°C (32°F)

5°C (41°F)

10°C (50°F)

15°C (59°F)

20°C(68°F)

ml CO2/kg·hr*

3

5

12

17

32

*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 20°C (68°F)

Responses to Ethylene

Celery is not very sensitive to exogenous ethylene at low levels and low temperatures. Loss of green color can result from exposure to 10ppm or higher ethylene concentrations at above 5°C (41°F).

Responses to Controlled Atmospheres (CA)

Controlled or modified atmospheres offer moderate benefit to celery. Delayed senescence and decay development have been observed at 2-4% O2 and 3-5% CO2.

Injury from low O2 (< 2%) or elevated CO2 (> 10%) will induce off-odors, off-flavors, and internal leaf browning. CA for mixed storage or long distance transport of celery and lettuce has some commercial application. Elevated CO2 levels delay leaf yellowing and decay but could not be used in mixed loads with lettuce (lettuce does not tolerate CO2 enriched atmosphere).

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