Potatoes - storage and processing
Practical Action
and shrivel. For long-term storage (up to twelve months), the optimum conditions are a
temperature near to 4°C. Commercial storage of potatoes involves first drying them to remove
surface moisture; then storage at 85 - 95% relative humidity and below 25°C to heal any
wounds and toughen the skin; a cooling phase to 4°C; holding at this temperature for the
storage period and then a conditioning phase before use, during which the tubers are slowly
warmed.
Potatoes should not be stored below 4oC because dark spots and internal discoloration can
occur. Low storage temperatures, below 10oC, also cause starch to be converted into sugar and
this increase in sugar content is undesirable if potatoes are used in fried products because
they darken excessively during frying. This also produces higher levels of acrylamide in fried
products (see below).
For artisan or small-scale storage, potatoes can be stored in cellars or underground pits. In a
lined pit, potatoes are piled on a bed of straw and the pile similarly covered with straw and
soil. This type of pit can only be used in areas where groundwater and rodents are not a
problem. The pit protects crops from sub-zero temperatures during the winter in temperate
regions or at high altitudes, or it protects them against heat in tropical climates. Provided that
any damaged or diseased pieces are removed before storage, they can remain in good
condition for several months. Another low-cost storage method is a buried barrel (Fig. 2a),
which is sealed against groundwater and rodents. Potatoes are placed in the barrel and the lid
is fitted loosely to allow for air movement. It is then covered with up to a thick layer of straw
and a layer of soil. A storage mound (Fig. 2b) is similar to an unlined pit and is used where
there is groundwater or a shorter storage period is required. Potatoes are piled on a layer of
straw on the ground and then covered with a layer of straw and soil.
Boards
Soil (8cm)
Straw (30 cm)
Drum with loose-
a) fitting lid containing
crops
Straw-filled
air vent
Crop
Drainage
channel
Straw (8cm)
Soil (8 cm)
Straw (30 cm)
b)
Figure. 2. Low-cost potato storage, a) buried drum, b) storage mound (Adapted from Ells et
al, 2011)
Processing
Potatoes are prepared in many ways as components of meals and a selection of these products
is included here as many are processed for food service outlets or as street foods. All involve
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