How to preserve sweet potatoes

In this brief guide, we are going to answer the question “How to preserve sweet potatoes ?”, and discuss the different methods used to preserve sweet potatoes.

How to preserve sweet potatoes

Studies show that consumer demand for sweet potato (yam) is growing exponentially, thanks to the rising interest in ethnic vegetables mediated by globalization and by nutraceutical research. For these reasons, both imports and consumption are rapidly growing, increasing by 100% over the last five years (1).

Sweet potatoes are preserved by :

  • Freezing: Sweet potatoes can be frozen after they are steamed, baked or roasted.
  • Canning: Sweet potatoes can be baked and then canned.
  • Dehydrating: Sweet potatoes can be baked or blanched and then dehydrated.

How to preserve raw sweet potatoes 

Fresh sweet potatoes are usually stored in a cool room to prevent sprouting. During the storage period, physicochemical properties of sweet potatoes may have been changed. The most noticeable change is the weight loss which has a significant influence on the quality of sweet potatoes (2).

Raw sweet potatoes have a long shelf-life. Under proper storage conditions, they can be preserved for up to six months. Sweet potato roots are chilling sensitive and should be stored between 12.5°C and 15°C (55°F to 59°F) with high relative humidity (>90%). A storage life of 6-10 months can be expected under these conditions, although sprouting may begin to occur after about 6 months depending on cultivar (3).

Raw sweet potatoes must be kept in a cool, dark and dry place. They must never be refrigerated or frozen before cooking. Refrigerating raw sweet potatoes will activate their sugars and cause faster spoilage. The best household area to store sweet potatoes is in the basement or cellar.

Sweet potatoes must never be washed before storage. Washing will introduce moisture which can cause microbial growth and faster spoilage. If the sweet potatoes have a lot of soil and dirt on them, it is best to clean them with a dry cloth or brush before storage.

After harvest, roots are immediately “cured” at 29–33°C and 85–90% RH with proper ventilation for 4–7 days. Curing heals wounds that occur during the harvest, first by a lignification beneath cells damaged at harvest, and second by the formation of a wound periderm beneath the lignified cells in a process called suberization. The healing provides a pathogen barrier and reduces desiccation at the wound site resulting in less weight loss during storage. Uncured roots do not store well but properly cured roots stored at 13–15°C and 85–95% relative humidity will be marketable for up to 12 months (5).

Sweet potatoes must also be stored away from other vegetables as they are sensitive to ethylene. Ethylene may cause them to sprout and rot faster. Exposure to ethylene (1 to 10 ppm) increases respiration rates and phenolic metabolism and adversely affects flavor and color of cooked roots (3).

How to preserve cooked sweet potatoes

Sweet potatoes are very versatile and can be used in a large number of dishes ranging from sweet to savoury. Cooked sweet potatoes can be preserved by freezing. 

Sweet potatoes can be cooked by either steaming, boiling, baking or roasting. Sweet potatoes can also be deep-fried or baked to produce sweet potato chips.

How to preserve baked sweet potatoes

Baked sweet potatoes can be frozen for up to 12 months. They must be allowed to cool down completely and then foil wrapped before freezing (4).

How to preserve steamed sweet potatoes

Steamed sweet potatoes can be frozen for up to 12 months. Peeled, steamed sweet potatoes must be allowed to cool down completely and then stored in a freezer-proof container. Flash freezing is preferred when preserving steamed sweet potatoes.

How to preserve roasted and mashed sweet potatoes 

Roasted, mashed potatoes can be frozen for up to 612 months. Puree of mashed potatoes must be stored in an air-tight container or a ziplock bag.

How to preserve sweet potatoes by canning

Cooked sweet potatoes can be preserved by pressure canning for up to 12 months at 90°F and up to 24 months at 70°C. The canned sweet potatoes must be stored at 50 and 70 °F in a dark place. 

Sweet potatoes can be canned whole, halved, or cut into chunks, in either syrup or water. Sweet potatoes can also be puréed and canned as a solid pack. The unit operations leading to the production of canned sweet potato roots include peeling, cutting, sizing, blanching, filling, syruping, exhausting, and retorting (5). 

How to preserve sweet potatoes by dehydration

Sweet Potato roots are cut into 2–3 mm thick slices and optionally blanched in boiling water for several minutes. The slices may be subjected to metabisulfite treatment before or during blanching to prevent browning. The blanched or unblanched slices are sun‐dried until the slices reach a moisture content of about 6–10%. Drying times vary from 4 hours to 5 days, depending on climatic conditions, and the dried slices are ground into flour (5).

Sweet potatoes can be dehydrated and stored in the proper conditions for about 12 months (6).

Sweet potatoes can be dehydrated in slices, pureed or in shredded form.

Dehydrated sweet potatoes can be consumed as a healthy snack. They can also be rehydrated by soaking in water and then used in dishes such as mashed potatoes and soup.

Dehydrating pureed sweet potato

Sweet potatoes are baked and mashed to form a puree. Water and seasoning can be added to make the puree but fats and oils must not be added.

The puree is spread at ⅛  to ¼ inches of thickness on the dehydrating tray. The puree is then dehydrated at 58°C for 6 to 8 hours.

Dehydrating sliced or diced sweet potatoes

Sweet potatoes are baked, cooled and then peeled. After peeling, the potatoes are cut into slices or diced. Cut potatoes are then placed evenly in a dehydrator tray and dehydrated at 52°C until they are crispy. 

Sliced sweet potatoes will dehydrate in 8-10 hours while diced sweet potatoes will take about 10-12 hours.

Dehydrating shredded sweet potatoes

Sweet potatoes are washed, peeled and shredded using a box grater. The shredded sweet potatoes are then blanched, cooled and drained. Next, they are spread evenly on a dehydrator tray and dehydrated at  52°C  until the pieces are tough.

How to use preserved sweet potatoes 

Preserved sweet potatoes can be used in numerous dishes. 

Cooked and frozen sweet potatoes can be thawed and then used as a substitute for fresh sweet potatoes in any recipe such as soups, mashed potatoes, filling etc.

Dehydrated sweet potatoes can be eaten by themselves as a snack or they can be rehydrated and then substituted for fresh sweet potatoes.

Both frozen and dehydrated sweet potatoes can be used in baking.  They can be used for baking muffins, cakes and even cookies

Other FAQs about Sweet Potatoes that you may be interested in.

Can Guinea Pigs Eat Sweet Potatoes?

Can you eat sweet potato on the keto diet?

How to know if sweet potato is spoiled

Conclusion

In this brief guide, we answered the question “How to preserve sweet potatoes?” and discussed the different methods used to preserve sweet potatoes such as freezing, canning and dehydrating. We also looked at the best storage conditions for raw potatoes and discussed how to use preserved sweet potatoes.

If you have any questions or comments please let us know.

References

  1. Galvao AC, Nicoletto C, Zanin G, Vargas PF, Sambo P. Nutraceutical Content and Daily Value Contribution of Sweet Potato Accessions for the European Market. Horticulturae. 2021, 7, 23. 
  2. Huang, Che-Lun, et al. Storage performance of Taiwanese sweet potato cultivars. J food sci technol, 2014, 51, 4019-4025..
  3. Cantwell, M., and T. Suslow. Sweet potato: Recommendations for maintaining postharvest quality. Perishables Handling, 2001, 107.
  4. Venema, C. Sweet potatoes: Using, Storing and Preserving. 2012. Michigan State University.
  5. Truong, V. D., et al. Sweetpotato production, processing, and nutritional quality. Handbook of vegetables and vegetable processing, 2018, 2.
  6. Harrison, J. A., and E. L. Andress. Preserving food: drying fruits and vegetables. University of Georgia cooperative Service, 2008, 2.