How to preserve potatoes

In this brief guide, we will answer the question “how to preserve potatoes” and discuss the methods used to preserve both raw and cooked potatoes.

How to preserve potatoes

China became the world’s largest potato producer in 1993 and currently accounts for almost one quarter of global potato production and about 28% of total cultivated areas (1).

Potatoes can be preserved by:

  • Raw potatoes: Curing and storing raw potatoes under proper conditions
  • Cooked potatoes: Freezing 
  • Dehydrating 
  • Canning

Potatoes are very versatile and durable vegetables and they can be eaten either as a main meal or a side dish.

How to cure raw potatoes 

Curing is a normal practice after potato harvested to promote dormancy and extend postharvest storage life, by preventing decay caused by microorganism during storage. Curing at 15 C for 14 days in dry conditions reduced the incidence of skin spot from 70% prick wounds infected down to 4%. In damp conditions, however, curing only reduced the problem down to 53% (2).

Freshly harvested potatoes must be cured before long term storage. Curing allows the potatoes to develop a harder outer skin that protects them from bruising and damage in the future.

To cure freshly harvested potatoes:

  • Sort through the potatoes and remove any bruised and damaged potatoes.
  • Scrub off the dirt and soil from the potatoes. Do not wash the potatoes.
  • Spread them out on a clean mat or newspaper in a basement or cellar. 
  • Allow the potatoes to cure for about 2 weeks.
  • After curing, store the potatoes in a dark, dry place inside a mesh bag, crate, or box with ventilation.

How to preserve raw potatoes

Early potatoes which are free from serious bruising and decay may be held 4–5 months at 4°C for table use provided that they are cured 4 or 5 days or longer at 13–18°C to heal wounds prior to storage (3).

Raw potatoes are one of those vegetables that must not be refrigerated or frozen, but they preserve well at room temperature. Raw previously cured potatoes, when stored properly, can last for about 8  months. The following measures will ensure that potatoes are stored under optimum conditions. However, changes in the composition of tubers occur during storage. Sugar and starch are the main components affected by post-harvest metabolism in potato tubers, which ultimately affects potatoes’ cooking, sensory, and processing characteristics (3).

  • The best place to store potatoes is a dry, dark place such as in a basement or cellar.

Potatoes need plenty of ventilation. They are best kept in an open crate, wicker basket or an open bag. A significant amount of heat is produced during respiration and if this heat is not removed then the temperature of the potatoes could increase. To maintain the temperature of the potatoes at a specific level, the heat evolved by the potatoes during respiration must be removed by cooling. It is also important to have a steady supply of fresh air during storage to provide the oxygen needed in respiration and to remove CO2 released during respiration (3).

  • Potatoes must be stored away from sunlight to prevent them from sprouting. When exposed to sunlight, potatoes may become greenish. This makes them toxic. Always discard any potatoes that show signs of greening or sprouting.
  • Store raw potatoes away from ethylene producing fruits and vegetables. Potatoes are sensitive to ethylene and may sprout or spoil upon exposure to ethylene. Some ethylene producing fruits and vegetables include apples, bananas and avocados to name a few.
  • Raw potatoes must not be washed before storage. Even a small amount of moisture can cause microbial growth and spoilage. If there is dirt and soil on the potatoes, brush them with a clean brush or a cloth before storage.

The main factors that influence the rate and form of sprout growth are variety, previous storage history, temperature, humidity, composition of the atmosphere, and degree of exposure to light (3).

How to preserve potatoes by freezing

Looking back also over the historical development of quality requirements for processed foods, freezing when properly carried out is undoubtedly the most satisfactory method for the long term preservation of vegetable produce (3).

Once they have been cooked, potatoes can be frozen just like any other vegetable. Frozen potatoes can be used in a variety of dishes. Frozen potatoes are best when used within 5 weeks due to significant loss in vitamin C (4).3 months.

When preparing potatoes for freezing, always pick and remove moldy, bruised, greened or sprouted potatoes.

Potatoes must be either blanched, mashed, roasted or fried before being frozen. 

Blanching is a thermal treatment commonly applied in a variety of vegetable preservation treatments and is particularly important in freezing because it impacts quality very strongly. The product is heated, typically by brief immersion in water at 85–100◦C or by steaming at 100◦C. The primary objective is to inactivate enzymes responsible for alterations in sensory quality attributes (off flavors and odors) and in nutritional value (loss of vitamins) during storage (3).

To preserve blanched potatoes by freezing  :

  • Boil potatoes until they are just cooked. Potatoes must still be a little form at this point. It is better to leave the skin on during blanching to preserve the nutrients.
  • Transfer the potatoes into ice water.
  • Drain off the excess water and allow the potatoes to cool down to room temperature.
  • Place the potatoes in a tray lined with parchment paper. Leave some space around each potato.
  • Place the tray in the freezer for a few hours, until all the potatoes are frozen.
  • Transfer the potatoes into a ziplock bag.
  • Squeeze out the excess air, seal, label, and place the bags back in the freezer.

To preserve mashed potatoes by freezing:

  • Boil the potatoes until they are soft and mash them by adding butter, milk, cheese and any additional ingredients of your choice.
  • Transfer the mashed potato into ziplock bags.
  • Squeeze out the excess air, seal, label, and place the bags in the freezer.

To preserve roasted or fried potato:

  • Peel and slice the potatoes. 
  • Blanch the potatoes by lightly boiling and then adding them to ice water.
  • Slightly fry the potatoes in heated oil.
  • Allow them to cool down to room temperature
  • Place the tray in the freezer for a few hours, until all the potatoes are frozen.
  • Transfer the potatoes into a ziplock bag.
  • Squeeze out the excess air, seal, label, and place the bags back in the freezer.

How to preserve potatoes by dehydrating

Drying is a widely used method of fruit and vegetable preservation.Water is removed to a final concentration, which assures microbial stability of the product and minimizes chemical and physical changes. Nowadays, drying is regarded not only as a preservation process, but also as a method for increasing added value of foods (3).

Potatoes can be preserved by dehydration. 

Potatoes must be blanched before dehydration. Blanch the potatoes by immersing them in boiling water for 5 minutes and then transferring them into ice water. Then dehydrate the potatoes using a food dehydrator at 135° F until they are crispy. Store the dehydrated potatoes in an airtight container in a cool, dark place.

How to preserve potatoes by canning

Pickling involves preserving foodstuffs under high acid concentration, enabling their preservation for over two years without refrigeration. Pickling imparts unique and desirable changes in flavor, texture and color that take place over time in fermented pickles. Microorganisms (mainly lactic acid bacteria, Micrococcaceae, Bacilli, yeasts, and filamentous fungi) play a pivotal role in the pickling of foodstuffs while affecting the quality and safety of the final product (5).

Canning is the least common method to preserve potatoes. Homemade canned potatoes will last for about 1218 months. Canning potatoes is the most time consuming and technical method of preservation. You can find a detailed process of canning potatoes here.

Other FAQs about Potatoes that you may be interested in.

How to Keep Potatoes from Sticking

Can you eat potatoes on a low carb diet?

Can you eat old potatoes?

Are potatoes healthier than bread?

Conclusion

In this brief guide, we answered the question “how to preserve potatoes” and discussed the different methods used to preserve potatoes.

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

References

  1. Mudege, Netsayi Noris, Silvia Sarapura Escobar, and Vivian Polar. Gender topics on potato research and development. The Potato Crop: Its Agricultural, Nutritional and Social Contribution to Humankind, 2020, 475-506.
  2. Wang, Qingguo, et al. Effects of postharvest curing treatment on flesh colour and phenolic metabolism in fresh-cut potato products. Food Chem, 2015, 169, 246-254.
  3. Pinhero, Reena Grittle, Robert Coffin, and Rickey Y. Yada. Post-harvest storage of potatoes. Advances in potato chemistry and technology. Academic press, 2009. 339-370. 
  4. Tudela, Juan Antonio, J. C. Espın, and M. I. Gil. Vitamin C retention in fresh-cut potatoes. Posthar biol technol, 2201, 26, 75-84.
  5. Behera, Sudhanshu S., et al. Traditionally fermented pickles: How the microbial diversity associated with their nutritional and health benefits?. J Funct Foods, 2020, 70, 103971.