How frozen peas are made

A frozen pea is often frozen within hours of leaving the vine, while a fresh one keeps aging on its way to the store.

stations: 6
things upstream: 8
raw sources: 4
steps from the ground: 5

The short version

A pea harvester strips the pods from the vines in the field, and the peas are shelled and rushed to the plant. They are chilled and washed, then blanched in hot water for a few minutes to stop the enzymes that spoil them. Cold air then freezes them as loose, individual peas.

Strip the vines

A pea viner machine strips peas from their vines in the field. Peas must go into the freezing process shortly after picking, or they spoil.

Goes in
Peas
Shell and sort

Peas are shelled and sorted. The more tender the peas, the more likely they are to be kept for the final product.
Chill and rinse

Peas are placed in ice water to cool, then sprayed with water to remove any dirt or dust.
Scald them briefly

The peas are boiled for a few minutes, which deactivates the enzymes that cause browning, off flavors and texture changes in storage. Then they are cooled quickly so the cooking stops.

a few minutes in hot water
Freeze each pea alone

Small foods are often frozen in a fluidized bed, where fast cold air from below lifts and tumbles the pieces. Quick freezing makes small ice crystals and keeps the cell structure intact. Other plants use air-blast tunnels.
Bag the peas

The free-flowing peas are weighed into bags and kept cold. They freeze as separate pieces, so the bag can be poured by the handful.

Goes in
Polyethylene

End of the lineFrozen peas

Worth repeating

The first pea harvesting machine able to shell peas through impact was invented around 1890 by John Alexander Chisholm.
Freezing slows spoilage because microorganisms do not grow when food is colder than about minus 9.5 °C.