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Peas: Snow and Snap Pod

Recommendations for Maintaining Postharvest Quality

Trevor V. Suslow and Marita Cantwell

Department of Plant Sciences, University of California, Davis

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Maturity & Quality

Introduction

Edible-Pod Peas include both Oriental or Asian (also Snow) flat type pods, harvested when the seeds are very small and immature, and the Snap or Sugar Snap Pea which resemble a typical fresh garden pea but with smaller seeds.

Maturity Indices

Snow Peas are selected for size and maximal recovery of bright green, flat pods with minimal seed enlargement. Older and yellowing pods are avoided by careful hand-harvesting.

Sugar Snap Peas are selected in a similar manner but some degree of seed-pod filling is desirable. Larger seeds rapidly become starchy.

Quality Indices

Edible-pod peas should be uniformly bright green (light to deep green but not yellow-green), fully turgid, clean, and free from damage (Thrip injury, broken pods). The stem and calyxes should be green and there should be very few blossoms attached to the pods.

U.S. Grades: U.S. Fancy, and U.S. No. 1, (established in June 1942)
Standards for Fresh Peas apply to Snap Peas but not Oriental Peas

Temperature & Controlled Atmosphere

Optimum Temperature

0°C (32°F)

Edible-pod peas are highly perishable and will not maintain good quality for more than 2 weeks. Wilting, yellowing of pods, loss of tenderness, development of starchiness and decay are likely to increase following storage beyond 14 days; defects occur faster at common distribution conditions of 5 to 10°C (41 to 50°F).

Relative Humidity

95-98%

Rates of Respiration

Temperature °C	Temperature °F	ml CO₂/kg·hr
0	32	15-24
5	41	27-38
10	50	34-59
15	59	89-101
20	68	123-180

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.
Respiration rates for edible-pod peas are an approximation based on values for unshelled garden peas; actual values remain to be determined.

Rates of Ethylene Production

Responses to Ethylene

Peas are moderately sensitive to exogenous ethylene. Accelerated yellowing and decay will result from extended exposure to low levels of ethylene during distribution and short-term storage. The calyx is more sensitive to ethylene than the pod.

Responses to Controlled Atmosphere (CA)

Reports vary widely in the benefit of CA for Sugar and Snap Peas. Atmospheres of 2 to 3% O₂ and 2 to 3% CO₂ are considered by UC Research to offer the best, but moderate, benefit to peas beyond that of rapid cooling and proper storage. Low O₂ may promote off-flavors and off-odors. Other studies report that 5 to 7% CO₂ extends pod quality at 0°C.

Disorders

Physiological and Physical Disorders

Freezing. Freezing injury will be initiated at -0.6°C (30.9°F). Freezing injury results in watersoaking typically followed by rapid decay by soft-rot bacteria.

Premature senescence. (Yellowing of pod, browning of calyx, loss of tenderness) will develop rapidly at temperatures 7.5°C (45°F) due to the high rate of respiration.

Harvesting and handling should be done with care to prevent damage to the pods and attached calyx.

Pathological Disorders

A variety of fungal pod-spotting and decay pathogens affect edible-pod peas. Common diseases include Chocolate Spot and Grey mold (Botrytis cinerea), Watery Soft Rot (Sclerotinia sclerotiorum), Rhizopus Rot, and Ascochyta Pod Spot. Bacterial Soft Rot is common following rough handling or freezing injury. Surface decay can occur readily, on weak calyxes (brown at harvest) and on blossom remains.

Special Considerations

Package-icing and top-icing loads may be used for Snow Peas but is typically detrimental to Snap Peas because surface moisture promotes decay. Improper CA/MA conditions in ready-to-cook vegetable medleys often leads to off-flavors and fungal decay (typically Botrytis grey mold) at the blossom-end of the pod.

Disorders Photos

Title: freeze injury

Photo Credit: Marita Cantwell, UC Davis

Title: Grey Mold

Photo Credit: Marita Cantwell, UC Davis

Date

February 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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