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Spinach

Recommendations for Maintaining Postharvest Quality

Trevor V. Suslow and Marita Cantwell

Department of Plant Sciences, University of California, Davis

Publications for this Commodity

Maturity & Quality

Maturity Indices

Spinach is selected for size and maximal recovery of clean leaves that are mid-maturity to young. Older and yellowing leaves are avoided when making the harvest cut. Generally 3-4 weeks of re-growth are required before a second harvest will yield adequate volume.

Quality Indices

Spinach, whether bunched or as leaves, should be uniformly green (generally not yellow-green), fully turgid, fairly clean, and free from serious damage. For bunched spinach, roots should be trimmed short to grade standards and petioles should be predominantly shorter than the leaf blade.

U.S. Grades: Bunched — U.S. No. 1, No. 2 (Oct. 1987). Leaves — U.S. Extra No. 1, No. 1, Commercial (Dec. 1946)

Temperature & Controlled Atmosphere

Optimum Temperature

0°C (32°F)

Spinach is highly perishable and will not maintain good quality for more than 2 weeks. Wilting, yellowing of leaves, and decay are likely to increase following storage beyond 10-14 days; faster at common distribution conditions of 5 to 10°C (41 to 50°F).

In a 1994 UC Davis study, an average of 17, 28, and 45% of leaves of 16 varieties had decay after 2, 3, and 4 weeks at 5°C, respectively. After the same periods at 5°C, 18, 25, and 45% of the leaves showed some yellowing. Commercial varities such as Imperial Spring, Shasta, Polka, Spectrum and Sporter had notably longer shelf- life than did varieties Bossanova, Spark and Space.

Optimum Relative Humidity

95-98%

Rates of Respiration

Temperature °C	Temperature °F	ml CO₂/kg·hr
0	32	9-11
5	41	17-29
10	50	41-69
15	59	67-111
20	68	86-143

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

Responses to Ethylene

Spinach is highly sensitive to exogenous ethylene. Accelerated yellowing will result from low levels of ethylene during distribution and short-term storage. Do not mix loads such as apples, melons and tomatoes with spinach.

Responses to Controlled Atmosphere (CA)

Atmospheres of 7-10% O₂ and 5-10% CO₂ offer moderate benefit to spinach by delaying yellowing. Spinach is tolerant to higher CO₂ concentration but no increase in benefits has been observed. Package film for prewashed spinach leaves is selected to maintain 1-3% O₂ and 8-10% CO₂.

Disorders

Physiological and Physical Disorders

Freezing Injury. Freezing injury will be initiated at -0.3°C (31.5°F). Freezing injury results in watersoaking typically followed by rapid decay by soft-rot bacteria.

Yellowing. Spinach is highly sensitive to exogenous ethylene (See Response to Ethylene).

Harvesting and handling should be done with care to prevent damage to the petioles and leaves. Bunching ties should not be too tight as crushed or split petioles may lead to rapid decay.

Pathological Disorders

Bacterial Soft-Rot (primarily Erwinia and Pseudomonas) is a common problem. Decay is usually associated with damaged leaves and stems.

Special Considerations

Package-icing and top-icing loads may be used. Frequent light misting may be done in displays to delay wilting of bunched spinach.

Date

May 1998

Use of Materials

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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.

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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