Fruit Produce Facts English
Recommendations for Maintaining Postharvest Quality
Maturity & Quality
Watermelon (Citrullus lanatus Thunb.) are harvested at full maturity as they typically do not develop in internal color or increase in sugars after being removed from the vine. The ground spot (the portion of the melon resting on the soil) changes from pale white to a creamy yellow at proper harvest maturity. Another indicator used at harvest include a wilted but not fully desiccated vine tendril proximal to the stem-end attachment. Destructive sampling is used to judge maturity of a population of watermelons. For seeded cultivars, maturity is reached when the gelatinous covering (aril) around the seed is no longer apparent and the seed coat is hard. Cultivars vary widely in soluble solids at maturity. In general, a soluble solids content of at least 10% in the flesh near the center of the melon is an indicator of proper maturity if the flesh is also firm, crisp and of good color.
U.S. grades Fancy, No. 1, and No. 2. Distinction among grades is based predominantly on external appearances.
Maturity & Quality Photos
Temperature & Controlled Atmosphere
10-15°C (50-59°F) Storage life is typically 14 days at 15°C (59°F) with up to 21 days attainable at 7-10°C (45-50°F).
85-90%; High relative humidity is generally advisable to reduce desiccation and loss of glossiness.
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.
Low: 0.1-1.0 µl/kg·hr at 20°C (68°F)
Exposure to an ethylene concentrations as low as 5ppm for 7 days at 18°C (64°F) will cause unacceptable loss of firmness and eating quality.
Controlled atmosphere storage or shipping are not recognized as offering controlled benefits for watermelon.
Physiological and Physical Disorders
Cut watermelon for slices or cubes for fresh-cut fruit salads have a very short period of optimal quality. Flesh becomes water-soaked and mealy. Varietal performance for fresh-cut is not currently available.
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.