Vegetables Produce Facts English

Belgian Endive (Witloof Chicory)

Recommendations for Maintaining Postharvest Quality

Marita Cantwell and Trevor Suslow

Department of Plant Sciences, University of California, Davis

Maturity & Quality

General Information

Witloof chicory or Belgian endive is a "chicon" or compact oval head of overlapping leaves produced from a harvested tap root. Forcing occurs in the dark at elevated temperatures 16-20°C (60-68°F) often in hydroponic trays and results in the cream-yellowish compact head or chicon after 3-4 weeks. Witloof chicory is a member of the lettuce family.

Maturity Indices

Maturity is based on chicon size and compactness and varies according to cultivar and the quality of the tap root (amount of carbohydrate reserves). The firm heads are harvested by snapping from the root.

Quality Indices

Quality is based on size, compactness, shape, and color. After trimming outer leaves, the chicons should be white with closed cream-yellow points and not have any torn leaves. Witloof chicory cultivars vary in flavor and bitterness (caused by sesquiterpene lactones). Chicons rapidly turn green if exposed to light and the flavor changes (see Special Considerations). Good quality chicons do not have any traces of green but are white with cream-yellow leaf edges.

Maturity & Quality Photos

Title: Greening

Photo Credit: Marita Cantwell, UC Davis

Temperature & Controlled Atmosphere

Optimum Temperature

0°C (32°F) is required to optimize witloof chicory storage and life. A shelf-life of 21-28 days can be expected at this temperature. At 5°C (41°F) a shelf-life of about 14 days can be expected. Witloof chicory is usually room cooled after packing. Placing chicons on ice for retail display will cause discoloration.

Freezing Injury. Freeze damage weakens the leaves and can lead to more rapid bacterial decay. During storage, freeze damage can occur if chicons are stored at

Relative Humidity

>95%

Rates of Respiration

Belgian endive chicons have moderate respiration rates:

Temperature	0°C (32°F)	10°C (50°F)	20°C (68°F)
ml CO₂/kg·hr	4-5	14-17	35-44

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

Ethylene production rates of harvested chicons are <0.1, 0.2, and 0.7 µL/kg·hr at 0, 10 and 20°C (32, 50 and 68°F), respectively.

Responses to Ethylene

Witloof chicory or Belgian endive is moderately sensitive to ethylene exposure. The main symptoms of ethylene injury are accelerated decay and discoloration of the leaf margins. Ethylene could also be expected to induce leaf abscission, but this effect may require a very long period at low storage temperatures.

Responses to Controlled Atmosphere (CA)

Some benefit to shelf-life can be obtained with low O₂ (3-4%) and high CO₂ to (4-5%) atmospheres at temperatures of 0-5°C (32-41°F). CA retards the development of browning on leaf edges. CO₂ atmospheres also retard discoloration of the butt also. To control greening, extremely low O₂ concentrations (<0.1%) are required.

Disorders

Physiological and Physical Disorders

Internal Browning. The warm forcing conditions for witloof chicory production can cause browning of the chicon axis. This is thought to be due to a localized calcium deficiency in the rapidly developing head.

Physical Injury. Breakage of the outer leaf margins often occurs during harvest, trimming and packing and causes increased browning and increased susceptibility to bacterial decay.

Pathological Disorders

Decay is not a common cause of postharvest losses of witloof chicory. However, bacterial rots caused by numerous bacteria (Erwinia, Pseudomonas and Xanthomonas spp.) can occur and result in a slimy breakdown of the infected tissue. Trimming outer leaves, rapid cooling and low storage temperature reduce development of bacterial rots. Sanitation during initial harvest, trimming and washing reduce bacterial decays.

Special Considerations

Exposure to light causes the chicons to turn green and become unmarketable. Packaging in paper liners in unvented boxes ensures dark storage during distribution. However at retail, the chicons will turn green within a few hours at 10-15°C (50-59°F) of exposure to display lights. Therefore only a few should be removed from the box at a time to reduce exposure to light. Another option is to place the chicons in a plastic box with a lid that excludes light. If kept cold 0-5°C (32-41°F) it takes longer than 2 days for greening to occur.

Date

February 2001

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.

http://ucanr.edu/sites/Postharvest_Technology_Center_/Commodity_Resources/Fact_Sheets/Datastores/Vegetables_English/?uid=19&ds=799 (Accessed January 18, 2014).

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