Peas

MATURITY & QUALITY

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 (CA)

Optimum Temperature

0°C (32°F); 95-98% R.H.

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 to10°C (41 to 50°F).

Rates of Respiration

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

< 0.1µl /kg·hr at 20°C (68°F)

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.