How to store red onions
In this brief guide, we will answer the question “how to store red onions?” with an in-depth analysis of the proper storage of red onions. Moreover, we will also discuss what is the shelf life of red onions and how to tell if they have gone bad.
How to store red onions?
To store whole red onions use a well-ventilated basket or a large bowl and always choose a cool, dark, and dry area (1,2).
Make sure that onions should be prevented from moisture or light because they lead to mold formation and sprouting (1,2).
Optimum temperature to store whole red onions is at 0 to 4°C (32 to 40°F). Since they are not sensitive to chilling injury, they can be stored at -2 to -3 °C (28 to 27 °F). But, storage at temperature below -4 °C (25 °F) may cause freezing injury (1,3).
Cut or chopped red onions should be put in an airtight container, to minimize exposure to air and moisture and stored in the refrigerator at 0 to 4°C (32 to 40°F) (4).
Cooked red onions should be placed in an air-tight container stored in the refrigerator (4).
If you want to extend the shelf life of red onions whether fresh, cut or cooked, you can put them in an air-tight container or freezer bag, and store in the freezer at -18 ºC (5).
What is the shelf life of red onions?
Usually whole red onions have a shelf life of 2 to 3 months when stored under optimal conditions in the fridge (1). At room temperature they can last for 2-3 weeks (6).
Peeled or cut red onions have a shorter shelf life because they are more susceptible to moisture loss and microbial contamination. They can last for about 10 days in the fridge. It’s not recommended to keep them at room temperature since they may spoil faster (7).
Cooked red onions can be kept in the fridge for 3-5 days, when properly stored (4).
When stored in the freezer, red onions can last for about 12 months. Cooked red onions can remain safe to eat for 2 to 6 months (5).
What affects the shelf life of red onions?
The factors that may affect the shelf life of onions can vary depending on various aspects such as the type of onion, storage conditions, and how fresh they were when purchased. Next you can find some of these factors (1,3,8,9):
- Moisture and High humidity: Exposure to moisture promotes microbial growth and can lead to mold formation and rot. High humidity environments can cause sprouting in onions, reducing their shelf life.
- Physical damage: Bruising or cuts disrupt the onion’s protective outer layers and accelerates moisture loss and microbial entry.
- Light exposure: Light exposure can stimulate sprouting, cause greening, accelerate softening, and degrade flavor and aroma. Sprouting alters texture and flavor while greening results in a bitter taste and unappealing appearance. Softening and deterioration occur faster leading to quality decline.
- Exposure to ethylene: Since ethylene can cause onions to ripen and spoil more quickly, you should not store them near other fruits or vegetables that produce this gas like bananas, apples and potatoes.
How to tell if red onions have spoiled?
To tell if onions have spoiled, you should be able to recognize the signs of spoilage. Spoiled onions have a very dry flesh with sprouts growing on the outside. Spots can also be found on the surface of spoiled onions, with some having a mushy surface with dents (10, 11).
Another sign to check is if the onions emit a foul or fermented smell. Red onions may also develop a slimy or mushy texture, which is a result of microbial breakdown and decomposition (12).
Fungi such as Aspergillus niger and Penicillium spp. are found in spoiled onions and attack colored and white onions during storage and transportation.
Penicillium fungus can infect onions during storage, causing the growth of a blue-green mold on the onion’s surface. This may result in bulb degradation and a decline in quality (10,11).
In this brief guide, we answered the question “how to store red onions?” with an in-depth analysis of the proper storage of red onions. Moreover, we discussed what is the shelf life of red onions and how to tell if they have gone bad.
1. The Commercial Storage of Fruits, Vegetables, and Florist and Nursery Stocks. Agricultural Research Service Agriculture, Handbook Number 66, 2016, 436-438.
2. Your Questions Answered.Fruits and veggies more matters. USDA.
3. Sohany, M., et al. Physiological Changes in Red Onion Bulbs at Different Storage Temperature. World Journal of Engineering and Technology, 2016. 04(02):261-266
4. How should I store cut fruit and vegetables?. USDA, 2023.
5. Silva, C.L.M. Home Freezing of Fruits and Vegetables. In book: Frozen food science and technology, 2008.
6. Food labeling and product dating. USDA.
7. Onions, Bulb, Ready-To-Use. USDA, 2010.
8. Qiu Y, Zhou Y, Chang Y, et al. The Effects of Ventilation, Humidity, and Temperature on Bacterial Growth and Bacterial Genera Distribution. Int J Environ Res Public Health. 2022;19(22).
9. Jin Gao, et al. Role of ethylene response factors (ERFs) in fruit ripening. Food Quality and Safety, 2020, 4, 15–20.
10. Ibemologi, A, Tolulope A. solation and identification of bacteria from exposed and sliced Allium cepa (onions). Journal of Microbiology & Experimentation. 2022, 10, 224-227.
11. Can you use onions with black mold?. USDA, 2023.
12. Agi, V.N., et al. Studies on Microbial Contamination of Cut and Exposed Onions. Journal of Advances in Microbiology, 2020, 20(5):1-11.