pumpkin storing
- To: "'Pumpkin'" <pumpkins@mallorn.com>
- Subject: pumpkin storing
- From: "* G* L* <G*@PSS.Boeing.com>
- Date: Wed, 10 Jun 1998 15:17:54 -0700
In my relentless search for pollen answers I came across this info on
pumpkin storage:
Harvested squash and pumpkins are still very much alive even though they
are mature and have been removed from the vine.
The objective of curing and storing is to prolong the storage life of
the fruit by slowing the rate of respiration and protecting
against storage rots.
Respiration rate of fruit is most effectively controlled by lowering the
temperature. For each 10oC (18oF) reduction in fruit
temperature, the respiration rate is reduced by approximately one-half.
Chilling injury can occur, however, to some fruits at
temperatures below 50oF.
Even though relative humidity (air moisture) has little effect on
respiration, a relatively high level (70 to 75%) is needed to
protect against excessive shriveling. Relative humidity greater than 85%
can enhance disease development.
When to Harvest
Immature squash and pumpkins do not store well; therefore, be sure that
fruit is mature before harvesting. Mature butternut,
acorn and hubbard type squash have very hard skins that cannot be
punctured with your thumb nail. Additionally, as squash
mature, the fresh, bright, juvenile surface sheen changes to a dull,
dry-appearing surface. Most true pumpkins have softer skin
than those mentioned above but will exhibit the same surface appearance
alterations.
Dead vines do not necessarily indicate the squash and pumpkins on the
vines are mature. When vines die prematurely from
disease, stress or early frost, fruits are usually immature, of low
quality, and will not store as successfully as those grown on
healthy vines which die naturally.
Guard Against Injury
Whether in a home, garden or commercial planting, special care should be
exercised to protect harvested fruit from excessively
high (>95 oF) and cold (<50oF) temperatures, asphyxiation, and
mechanical injuries such as scratches, cuts or bruises. Not
only are mechanical injuries unsightly, they also provide an easy
entrance for various rot-producing organisms. Packing lines
and all conveyances should be padded with old carpeting, foam rubber or
similar shock-absorbing material. Ideally, large fruit,
such as pumpkins, should not be stacked on top of each other. Padding
material, such as grain straw, should be used liberally if
fruits have to be stacked during harvest. If they must be stacked for
shipping, they should never be more than three fruit deep.
Curing and Storage
Storage facilities should be equipped with accurate temperature and
humidity controls, and a system to provide at least one air
exchange per day. A fan to provide air circulation is also recommended
to maintain uniform temperature and humidity
throughout the storage room. There is limited information on the value
of a curing period. Except for acorn types, which lose
their quality during curing, experience tends to support a 10-day curing
period with 80 to 85oF and a relative humidity of 80 to
85%. After the curing period, maintain temperatures as indicated in
Table 1 below.
Table 1. Recommended optimum storage conditions for pumpkins and winter
squashes
Type
Relative
Humidity
Temperature
Conditions
Approx. Length
of Storage
Remarks
Pumpkins
50 to 75%
50 to 55oF
2 to 3 months
Fruit should be
mature. Don't store with apples.
Hubbards
70 to 75%
50 to 55oF
5 to 6 months
Stores well.
Acorn
50 to 75%
50oF
5 to 8 weeks
At temperatures
>55oF, surface becomes yellow and
flesh becomes
stringy.
Butternut or Buttercups
50 to 75%
50oF
2 to 3 months
Degree of
maturity not as important as for other
types.
When winter squash are removed from storage, they should be marketed or
consumed immediately, as rot can develop
quickly. Black rot, dry rot, and bacterial soft rot are the principal
causes of spoilage in stored winter squash.
Postharvest Diseases
Winter squash and pumpkins have hard 'skins' and firm, starchy rinds
that may rot while still on the vine, after harvest, or in
storage. In North Carolina, these rots are typically caused by fungi
such as Fusarium, Alternaria, Pythium, anthracnose
(Colletotrichum) and gummy stem blight (Mycosphaerella) fungi. On
occasion, other fungi and soft-rot bacteria (e.g. Erwinia
caratovora) may cause rots, especially during hot, wet weather.
Infection of fruit usually originates from injuries on mature fruit
after harvest. The following summarizes key considerations for reducing
fruit rot.
Steps to Minimize Squash and Pumpkin Rots
1.Maintain a good fungicide- and insecticide-spray program during the
growing season to minimize foliar diseases (leaf
spots and blights and insect problems.
2.Avoid blossom-end rot of fruit by fertilizing and liming fields
according to recommendations from soil test reports and by
irrigating when needed.
3.Avoid injuring fruit while on the vine.
4.Harvest fruits when they are mature and the rind is hard, but
before night temperatures are below 40oF and well before
a frost or a hard freeze.
5.Do not harvest or handle wet fruit. Do not let harvested fruit get
wet.
6.Harvest fruit by cutting the peduncle (stem) with pruning shears to
leave a 3- to 4-inch handle for pumpkins and about a
1-inch stump for squash.
7.Harvest, pack, handle, and store fruit carefully to avoid injuries.
8.Discard all fruit that are immature, injured, or have rot or
blemishes. These fruit should not be harvested or stored.
9.Do not pick up freshly harvested fruit by the peduncle, because it
may separate from the fruit and provide easy access
for rot organisms.
10.Do not stack the fruit higher than 3 ft.
11.Do not permit harvested or stored fruit to get wet.
12.Washing is usually not desirable, but if washing is necessary, be
sure the water is chlorinated (at least 50 ppm,
approximately one part 5.25% liquid bleach to 999 parts water).
Prepare fresh wash solution when the water becomes
cloudy and chlorine cannot be detected. Dry thoroughly.
13.For better keeping, some growers cure pumpkins for 10 to 20 days at
80 to 85oF with good ventilation (e.g. four air
exchanges per day).
14.Harvested fruit should be stored with good ventilation (at least
one air exchange per day) at 50 to 55oF and 50 to 75%
relative humidity. Standard refrigeration temperatures (35 to 45oF)
may cause chilling injuries and shorten shelf life.
Storage at high temperature may result in excessive loss of weight,
color, and culinary qualities, while high humidities may
promote rots.
15.Storage life is typically 2 to 3 months without significant loss in
quality.
Published by
North Carolina Cooperative Extension Service
---------------------------------------------------------------------
To sign-off this list, send email to majordomo@mallorn.com with the
message text UNSUBSCRIBE PUMPKINS
