Global: Washed Potatoes Need Cured Skin and a 30 mm Size Spread per Pack, Codex Standard Says
International standards require ware potatoes to have cured skin, no abnormal moisture and at most 10% defects in Class I. Packs up to 5 kg may be limited to a 30 mm size spread.
What must washed potatoes meet to be accepted by a buyer? Each retail chain and packer sets its own specification. But the common base is set by international marketing standards. The main one is the Codex Standard for Ware Potatoes, CXS 339-2020, adopted in 2020. It applies to potatoes after preparation, such as brushing or washing, and packing.
Skin and moisture
Under the Codex text, potatoes must be intact, sound, firm, clean and free of abnormal external moisture. Condensation after removal from cold storage is allowed. Ware potatoes must be “sufficiently developed with cured skin”, taking account of the variety. The same wording appears in the UNECE standard FFV-52, according to a 2018 UNECE comparison of the two texts.
Superficial common scab covering more than 25% of the surface and deep or powdery scab more than 2 mm deep are listed as defects. Total tolerance for tubers that do not meet class rules is 5% in Extra Class and 10% in Classes I and II. Size tolerance is 10% in all classes.
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Size range in the pack
For sales packs of up to 5 kg net, uniformity may be limited to a maximum of 30 mm between the smallest and the largest tuber. The UNECE standard, according to the 2018 comparison, sets minimum sizes of 35 mm mesh for round ware potatoes, 30 mm for long varieties and 28 mm for early potatoes.
Why skin set decides washing
Postharvest specialists at the University of California, Davis note that immature potatoes have a thin, poorly developed skin. They bruise easily, and skinning leads to shrivelling or decay. Early-crop potatoes keep quality for only 3 to 5 weeks. Curing for 8 days at 15°C and 95% relative humidity can allow storage for up to 5 months at 4°C. Colorado State University advises mechanical vine killing 14 to 21 days before harvest to set the skin.
Why it matters
Washing removes the soil that hides skin defects. Scab, bruises and skinning become visible on the packing line, and a lot can fail the 5% or 10% tolerance only after washing. Growers who sell to washers should plan haulm destruction early enough for the skin to set, and check scab levels before the crop leaves the farm.
The topic was raised by practitioners in the MAX messenger chat «КАРТОФЕЛЬ И Т.Д. (Potato etc.)», a community of more than 1,100 potato growers and industry specialists. Participants are not named. Join the discussion.
Photo: Mobile potato washing on a farm (illustrative). David Wright / Wikimedia Commons, CC BY-SA 2.0
