How often do you use half of an onion and store the other half in a plastic bag inside the refrigerator? You may have heard the claim that leftover cut onions are a particular hazard and cause of food poisoning. This claim states that cut onions are somehow a magnet for bacteria and that you should never save leftover onions but should discard them immediately. Are onions “poisonous” and dangerous? Should you never save leftover onions for later? Well, this claim came from famous blog post back in 2008 that has since been removed. However, the belief has persisted and has been spread through social media and other internet posts. It is a myth! There is nothing inherently dangerous about leftover onions and you can safely store them in the refrigerator for up to seven days.
Onions do not contain any compounds that are dangerous when the onions are cut or stored. Likewise, onions do not attract bacteria or present a more favorable environment for bacteria compared to other foods. This myth was essentially made up and presented on the web by one source, from where it was disseminated.
Two compounds in onions, allicin and quercetin, have been shown to have antibacterial activity. Other compounds like propenesulfenic acid, flavonoids, and fructo-oligosaccharides, kaempferol, leteolin and quercetin derivatives may contribute to the anitbacterial activity of onions. Onion juice or onion extracts may be useful as bacterial inhibitors. 1Kavita Sharma, Neelima Mahato, Yong Rok Lee,
Systematic study on active compounds as antibacterial and antibiofilm agent in aging onions, Journal of Food and Drug Analysis, Volume 26, Issue 2, 2018, Pages 518-528, ISSN 1021-9498, https://doi.org/10.1016/j.jfda.2017.06.009. (https://www.sciencedirect.com/science/article/pii/S1021949817301369),2Kabrah, Ahmed M., et al. “Antibacterial Effect of Onion.” Scholars Journal of Applied Medical Sciences (SJAMS) , Nov. 2016, https://doi.org/10.21276/sjams.2016.4.11.53.
How To Store Leftover Onions
Both fresh and cooked onions can be safely stored in the refrigerator. The peel of an onion may contain more of certain antibacterial compounds. However, the peel may also be contaminated with dirt and bacteria. So, it is best to remove the peel before storing leftover onions. When storing half of an onion, store the peeled onion in a sealed plastic bag in the refrigerator. You can also wrap the onion in plastic wrap or place it in a sealed storage container. Half an onion will keep well for around 5 to 7 days in the fridge. If the edges of the cut onion look dry when you want to use it, simply slice off the dry part.
Store sliced onions in an airtight container or plastic bag. Sliced or chopped onions will not last as long as an intact half onion but can be safely stored in the refrigerator for a few days.
Before placing leftover onions in the refrigerator, make sure they are sealed tightly or the odor from the onions will escape into the air inside the refrigerator, potentially impacting the smell and taste of other foods.
Cooked onions can be stored in the fridge for 4 to 5 days in a tightly sealed container.
Freezing Onions for Storage
When freezing onions, it is best not to a freeze whole or halved onion. Before placing onions in the freezer for storage, chop the onions to the size you want to use and store them in a freezer bag. Use within six months for best results.
Sources
Discover more from CulinaryLore
Subscribe to get the latest posts sent to your email.