How to store cut onions?

In this brief guide, we will answer the query, “How to store cut onions?” and will discuss how to properly store onions.

How to store cut onions?

To store cut onions, wrap them in a plastic sheet or reusable bag and place them in the refrigerator. They will be fresh for up to 10 days in the refrigerator without spoiling. Depending on the temperature, pre-cut onions can be stored for even longer. In a study, slicing onions enabled a higher stability of the physicochemical and biochemical aspects in comparison to dicing. Storage of slices at 0°C allowed preservation for up to 15 days (1).

Keeping onions in a cool, dark, dry place is the ideal storage method.

Throughout the year, regular yellow onions are accessible. Keeping onions in a cold, dry, dark, and well-ventilated space like a pantry or cellar is recommended by the National Onion Association (NOA).

Because they are so permeable, this is why. They may grow or decay if exposed to excessive temperatures or humidity. According to one research, onions do best when stored at a temperature of 40–50°F (4–10°C). Temperatures in this range are ideal for preserving their properties.

On the other hand, onions have a good storability compared to other crops. Plants, lifted at maturity and dried so that roots, shoots and skin are completely dry, keep well. The bulbs remain dormant at both low and high temperatures allowing high temperature storage in the tropics and refrigerated storage in temperate regions. Where modern refrigerated or controlled atmosphere storage is available, bulbs can be kept for up to 9 months (2).

To avoid mold and decay, it’s essential to have enough ventilation. An open basket, bamboo steamer, mesh bag, netting bag, or even pantyhose may be used to store the food.

Because of inadequate ventilation, onions may rot fast if they are stored in plastic bags. As a result, they can endure longer in the dark. In the absence of direct sunshine, temperatures and humidity are less likely to fluctuate, which may speed up the deterioration process.

Ventilation, according to studies, decreases onion decay. When the aeration and air movement in bulk storage are improper and very poor, it results in rise in storage temperature, which adversely affects the physiology and pathology of the stored product. Forced air ventilation system has a great scope in reducing the storage losses in bulk storage of onion since fairly even temperatures could be maintained in the store (3).

Avoid Storing Whole Onions in the Fridge

Store-bought onions have a papery peel because they were cured quickly after harvesting. They will last longer if they are properly cured.

Onions should be kept in a cool, dry, dark, and well-ventilated location since they are susceptible to mold and mildew. These circumstances prevent them from absorbing too much moisture or becoming overheated or damp.

Onions that are kept in the refrigerator are subjected to frigid and damp temperatures. Due to their high absorption capacity, they may quickly turn mushy and spoiled if left out.

However, low temperatures are necessary to avoid sprouting, thus low temperatures keep onions dormant and refrigeration must be used to further delay sprouting. Onions with relatively high dry matter content can tolerate temperatures just below 0°C, but those with low dry matter may be damaged by freezing (4). According to the USDA, onions may be kept in the refrigerator for 2 months, while in the freezer, the shelf life of onions is 12 months.

Onions that have been peeled, sliced, or diced are exempt from this rule. Chopped or sliced onions can only be kept in the fridge for 7–10 days, however, peeled onions may stay in the fridge for up to two weeks.

How to Keep Shallots Fresher for Longer?

Shallots are closely related to onions, but their softer and sweeter flavor sets them apart from onions. Shallots should be kept in a cold, dry, dark, and well-ventilated location, much like ordinary onions, The pantry, basement, cellar, or garage are included in this category.

The optimal storage conditions of shallots are, therefore, similar to the storage conditions for onions. Maintaining proper air circulation is essential to keeping shallots fresh and flavorful. They should not be exposed to high temperatures, which induces sprouting and weight losses. This method of storing shallots should keep them fresh for 30 days or more. As an alternative, shallots may be frozen for six months. However, many losses occur during storage. After a prolonged period, and when sprouting starts, a considerable increase in the amount of reducing sugars (i.e. fructose and glucose) can occur. Changes of vitamin C (ascorbid acid) during storage, also depend on variety and storage condition. Content of vitamin C is better preserved in storage conditions at 0−2°C in the cold room. Studies show that there were higher losses of the content of vitamin-C in bulbs stored in air ventilated storage in comparison to the storage under refrigeration (at 0−2°C) (4).

Soak the shallots in water for a few minutes before placing them in an ice cube tray. Once the shallots have been peeled, keep them in an airtight container or resealable bag in the freezer.

 At various stages of processing, how to keep onions fresh?

An onion’s lifespan may be extended by storing it in the right way. Various processing phases need different storage methods.

Peeled

Refrigeration should be used as soon as an onion has been peeled to prevent bacterial infection. Make sure your fridge is set to 40°F (4°C) or below to keep it fresh. Peeled onions, according to the USDA, may be kept in the refrigerator for 10–14 days.

Cut, slice, or dice onions

Cut or chopped onions keep for up to ten days in the refrigerator. Put them in a resealable container or plastic wrap and store them away. Alternatively, many supermarkets sell pre-sliced onions. Keep them refrigerated and utilize them before they expire.

A study analyzed onions minimally processed using two types of cut (10 mm cubes and 3–5 mm thick slices) and stored at different tem-peratures (0, 5, 10 and 15°C). Results showed that fresh-cut onions stored at 0°C were less pungency, had lower respiratory rate levels and less variation of total phenolic, anthocyanin and quercetin contents among the temperatures investigated. In addition, the physicochemical aspects and appearance changed less with fresh-cut onions stored at 0°C. Moreover, slicing enabled a higher stability of the physicochemical and biochemical aspects in comparison to dicing. Storage of slices at 0°C allowed preservation for up to 15 days (1).

It is possible to freeze chopped, sliced, or diced onions for up to six months. Soups, stews, and casseroles are the finest places to put them.

Cooked

Onions that have been cooked may be kept in the refrigerator for three to five days. Within a few hours of cooking, store them in an airtight container or resealable bag. In the long run, they may get infected with germs. During storage, browning may occur. This can be prevented by adding 0.05% ascorbic acid. A study showed that cooked onions stored with onion juice, added by lactic acid, glucose and ascorbic acid could be stored for 3 weeks (5).

Plus, they keep for three months in the freezer after they’ve been cooked. You may increase the shelf life of onions by pickling them. To prevent germs from growing and spoiling the veggies, they must be kept in a solution that inhibits their development. They can survive for up to six months if prepared in this manner (5).

To make pickled onions, combine peeled onions with vinegar, salt, sugar, and other seasonings to taste in a glass or ceramic jar. They’ll last longer if you put them in the fridge once they’ve been opened.

How to store Spring Onions and Leeks?

Many people are unsure whether spring onions and leeks are interchangeable terms. Scallions, or young onions, are another name for spring onions. They feature hollow green leaves because they are picked before the bulb is completely developed. 

Green/spring/salad onions or scallions are immature onions grown at high density for a short season. The market often does not distinguish between A. cepa and A. fistulosum for this use. These must be harvested and sold within a few days and are popular both for salad and cooked use. A similar product is semi-bulbed onions, again harvested before maturity and sold quickly; it provides a larger amount of bulb tissue than scallions (2).

Unlike spring onions, leeks don’t have a bulb to store their flavor and nutrients. Larger, crunchier, and sweeter, these pretzels offer a more substantial crunch. Leeks and spring onions are kept similarly because of their numerous similarities.

Spring onions and leeks may be stored in a jar of water on your counter if you intend to use them within a few days. To avoid wilting, make sure your kitchen isn’t too hot or damp. For longer-term storage, tie the stems with a rubber band and cover them in a slightly moist paper towel. Afterward, store them in the crisper section of your refrigerator for up to two weeks.

Spring onions and leeks may be chopped and frozen to extend their shelf life. Take care to keep them in an airtight container or resealable bag. According to the USDA, spring onions may be kept for 1 week in the refrigerator or up to 12 months in the freezer.

Other FAQs about Onions that you may be interested in.

Can you eat onion stalks?

Can you eat onion skin?

Does Onion Powder Go Bad

What is brown onion?

Conclusion

In this brief guide, we answered the query, “How to store cut onions?” and discussed how to properly store onions.

References

  1. Berno, Natalia Dallocca, et al. Storage temperature and type of cut affect the biochemical and physiological characteristics of fresh-cut purple onions. Postharv Biol Technol, 2014, 93, 91-96.
  2. Griffiths, Gareth, et al. Onions—a global benefit to health. Phytother res, 2002, 16, 603-615.
  3. MN, Dabhi, N. C. Patel, and N. K. Dhamsaniya. Effect of storage conditions on the quality characteristics of onion. J Food Sci Technol, 2008, 45, 376-377.
  4. Ilić, Z., et al. The effect of long-term storage on quality attributes and storage potential of different onion cultivars. IV Balkan Symposium on Vegetables and Potatoes 830. 2008.
  5. Hlavaty, P. The continuous cooking of onions for food processing and food service application. 199.7