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Recommendations for Maintaining Postharvest Quality

Trevor V. Suslow and Marita Cantwell

Department of Plant Sciences, University of California, Davis

Maturity & Quality

Maturity Indices

Maturity is generally based on marketable size after threshold days beyond seed sowing has been reached (commonly 75 to 85 days). Some varieties transition from green to red or red-purple leaves at maturity or the onset of cool weather. Head-forming radicchio are firm and compact at maturity. Leaf raddichio have a long conical shape similar to Romaine lettuce. Radicchio should be harvested with a small stub of root remaining to help retain leaf attachment.

Quality Indices

Turgid leaves or firm, compact head with bright appearance typical of variety. Generally, bright white midribs with no cracking or splitting. Absence of marginal leaf necrosis, insect damage, harvest or packaging damage. Absence of bacterial decay at the root end.

Maturity & Quality Photos

Title: Quality

Photo Credit: Adel Kader, UC Davis

Temperature & Controlled Atmosphere

Optimum Temperature

Store at 0°C (32°F). Under these conditions, quality may be retained for 16 to 21 days. Radicchio are generally packed, after thorough precooling, with polymer film liners inside corrugated containers to prevent water loss.

Relative Humidity

95% or higher

Rates of Respiration

We have recently begun testing the respiration rates of radicchio. For guidance, use the following values:

7.5°C (45°F) 12ml CO2/kg·hr
20°C (68°F) 25ml CO2/kg·hr

Rates of Ethylene Production

Low, 0.6 to 1.0 µl C2H4/kg·hr at 20°C (68°F)

Response to Ethylene

Exposure to ethylene appears to increase marginal leaf browning and fungal decay. Accelerated pigmentation, pink to purple, of the white midribs occurred after 6 days at 10 ppm C2H4 and 7.5°C (45°F); = 98% R.H.

Responses to Controlled Atmospheres (CA)

The specific responses of radicchio to CA are not well defined at this time. Atmospheres of 3% O2 and 5% CO2 may be beneficial but low temperature is the best method for quality retention. In recent, preliminary, studies low oxygen conditions resulted in internal browning in head radicchio.


Pathological Disorders

Radicchio are highly susceptible to Bacterial Soft Rot caused by Erwinia cartotovora at warmer storage temperatures and pectolytic Pseudomonas at lower refrigeration temperatures. Bacterial decay is common when harvesting methods cut across the basal leaves of head radicchio. Leaf margin necrosis and storage decay caused by Botrytis cinerea is also common, even with good temperature management.


May 1999

Use of Materials

The UC Postharvest Technology Center grants users permission to download textual pages (including PDF files) from this World Wide Web site for personal use or to reproduce them for educational purposes, but credit lines and copyright notices within the pages must not be removed or modified.

Except for these specified uses, no part of the textual materials available on the UC Postharvest Technology Center Web site may be copied, downloaded, stored in a retrieval system, further transmitted or otherwise reproduced, stored, disseminated, transferred or used, in any form or by any means, except as permitted herein or with the University of California's prior written agreement. Request permission from UC Postharvest Technology Center. Distribution for commercial purposes is prohibited.

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. (Accessed January 18, 2014).

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