Commercial Postharvest Handling of Strawberries
(Fragaria spp.)
Alvaro Rivera and Cindy Tong
Copyright ©
2009 Regents of the University of
Minnesota. All rights reserved.
Strawberries are appreciated for their flavor and
delicacy. They have very high respiration rates and therefore are highly
perishable. They can be kept for up to 5 to 7 days if precooled immediately
after harvest and kept at 32 degrees F.
Harvesting
Strawberries are usually hand-harvested, graded, and packed in the field.
Harvest when temperatures are cool, either early in the morning or evening. Pick
berries that are ripe but not over-mature (pink or red but not mushy), leaving
only a short stem and the calyx, and place directly into pint baskets or flats.
Berries that will be used for dipping should be harvested with long stems and
placed into flats so that the stems do not touch other fruit. Avoid bruising or
nicking fruit. Transport immediately to the shed or shade in the field if this
is not possible.
Cool fruit immediately after harvest by forcing cool air through the flats. This
is preferable to room cooling, as forced air can cool berries to 34 degrees F
within an hour, whereas room cooling may take 9 hours.
Storage
Store strawberries at 32 degrees F and 90 to 95% relative humidity. After a
few days in storage, fruit may lose some color, shrivel, and lose flavor. Berry
shelf life can be extended by using 10 to 30% carbon dioxide in refrigerated
storage, usually during transport. This can be done by packing berries in
containers with dry ice or covering pallets with coated fiberboard or
heat-shrink polyethylene film. Pallet loads can also be covered with
polyethylene bags and injected with carbon dioxide gas. Off flavors can develop
if carbon dioxide levels are above 30%.
Diseases
The major postharvest diseases of strawberries are gray mold rot caused by
Botrytis cinerea, Rhizopus rot, and leather rot caused by Phytophthora
spp. The symptoms of gray mold rot are firm, brown, dry lesions covered by
gray-brown spores, sometimes turning into fluffy white mold. It can spread in
storage, even at low temperatures. Rhizopus rot causes juice leakage from fruit,
developing into white mold with black spore-heads. Tissue affected by leather
rot become discolored and tough, and may leak. Under humid conditions, a white
mold may develop.
Other diseases
include the following:Disease | Causal Organism | Symptoms |
---|
Black spot | Colletotrichum
spp. | circular, sunken, water-soaked, brown lesions,
developing into pink, brown and black; does not spread from fruit to fruit | Cottony rot | Sclerotinia
sclerotiorum | watery flesh; white, cottony mold | Rhizoctonia brown rot | Rhizoctonia
solani | hard, brown rot on underside, with clear
definition between healthy and diseased tissue |
For More Information
For information covering related areas, consult the following Minnesota
Extension Service publications. They are available from your county extension
office or by writing to the University of Minnesota Extension Store, 20 Coffey Hall, 1420 Eckles
Avenue, University of Minnesota, St. Paul, Minnesota 55108-6064.
FS-6236 Commercial Postharvest Handling of Fresh Market Asparagus (Asparagus officinalis)
FS-6238 Commercial Postharvest Handling of Fresh Market Apples (Malus sp.)
FS-6237 Commercial Postharvest Handling of Potatoes (Solanum tuberosum)
BU-1880 Commercial Vegetable Pest Management Production Guide1996
BU-5886 Nutrient Management for Commercial Fruit and Vegetable Crops in Minnesota
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