Cucurbita spp (Cucurbita maxima, C. pepo, C. moschata)
The terms pumpkin and squash are often used interchangeably. Pumpkin generally describes what Americans call winter squash (zucchini is an example of summer squash), which are hard-skinned, hard-fleshed, mature fruit. There are many different varieties available. The most common are round in shape with a thick hard skin ranging from blue-grey in colour to orange-red, with orange flesh.
Pumpkins should be full sized and well formed with the stem intact. They should be well matured with good rind development typical of the cultivar. Internal quality attributes are strong colour, heavy dry weight, and high sugar and starch contents. The fruit may have a tender rind when freshly harvested. Curing in the field (with protection from the sun) before handling and stacking into bins or wagons will help to harden or cure the rind.
Postharvest storage temperature
Optimum temperature is 12.5–15°C. Pumpkins and winter squash are chilling sensitive when stored below 10°C. Depending on the cultivar a storage life of 2–6 months can be expected at 12.5–15°C. For green rind squashes, storing at 15°C may cause degreening, undesirable yellowing, and texture loss. They can be stored at 10–12°C to prevent degreening, although some chilling injury may occur at the lower temperature. High storage temperature (>15°C) will result in excessive weight loss, colour loss and poor eating quality. Freezing injury can occur at temperatures below -0.8°C.
Controlled atmosphere storage
Atmospheres containing 7% CO2 can be beneficial by reducing loss of green color. Yellow squash, however, appear not to be benefited by 5–10% CO2. Lowering the O2 concentration does not appear to provide any benefit.
Exposure to ethylene will degreen squash with green rinds. It will also cause abscission of the stem, especially in less mature fruit.
Moderate relative humidity (50–70%) with good ventilation is essential for optimum storage as high humidity will promote decay. However, 50–70% relative humidity will reduce decay during storage, though significant weight loss will occur.
Disease & infection
Several fungi are associated with decay during storage including fusarium, pythium, anthracnose (colletotrichum) and gummy stem blight or black rot (mycosphaerella). Alternaria rot will develop on chill-damaged winter squashes. Fruit that are overmature at harvest (>2 weeks beyond optimal harvest date) will tend to have more storage decay.
Steam or bake pumpkin for maximum nutrient content. Brighter orange flesh is healthier it will be for you, as more beta-carotene is present, which our bodies convert into vitamin A.