Freeze drying of pumpkin puree – a summary

Writen by Martina Vavrusova Hedegaard, Ph.D., Technologist, SD Freeze Drying

In general

  • Pumpkins in general are vegetables native to South America but nowadays they are grown in EuropeAustraliaNew ZealandIndia, but also in Southeast Asia including Thailand, Indonesia, Malaysia and other countries.
    It has been reported that pumpkin production has increased annually by 2.2 % and from 1992 to 2012 pumpkin production has increased to 25 million tonnes.
  • Pumpkins belong to the family Cucurbitaceae and the genus (family) Cucurbita. There are five domesticated species of which the three species Cucurbita pepo L.Cucurbita maxima Duchesne, and Cucurbita moschata Duchesne, represent the most economically important species cultivated worldwide.
  • Generally, pumpkins are quite stable after harvesting (1 – 3 months) but after peeling they are more susceptible to microbial spoilagemoisture losscolor changes and softening.
  • Because of the large size of pumpkins and difficulties in removing their strong peels there is a high demand for suitable processing techniques, which results in a final product with valuable nutritional qualities. Therefore, drying and powdering are suitable techniques for prolonging shelf life and maintaining the nutritional value of pumpkin.
  • The pumpkin powder is an alternative to fresh pumpkin with many nutritional benefits. It has storage and transportation advantages over fresh pumpkin due to its longer shelf life.
  • The pumpkin powder is used as a supplement to cereal flours in bakery products like bread, cakes, and cookies. It is also used in soups, spices, and sauces. Pumpkin powder has a highly desirableand pleasant flavor, good sweetness, and a deep yellow-orange color.
  • Therefore, in order to prolong the shelf life of pumpkins for retail markets and in order to best maintain nutritional qualities, freeze drying is the most appropriate technique.

 Nutritional values

  • Pumpkin flesh is an excellent source of β-carotene. β-carotene is a red/orange natural pigment (carotenoid) found in plants and fruits. It is known as a precursor of vitamin A, which the human body converts into vitamin A (healthy skin and mucous membranes, good eye health and vision). β-carotene has been studied as an antioxidant for its ability to inhibit oxidation of other molecules known as radicals, which damage cells and eventually lead to cancer and other chronic diseases. Carotenoids in general, including β-carotene can promote health benefits when taken at dietary levels.
  • Pumpkin is a good source of B-vitamins (water-soluble) such as B6 (pyridoxine), B1 (thiamine), B2 (riboflavin), B9 (folic acid), vitamin Kvitamin C, and minerals such as potassium, phosphoru