Storing onions
Question: I heard that peeled fresh onions shouldn’t be stored, as they can become toxic. Is this true, and if so, why?
Answer: No, it’s not true that peeled fresh onions become toxic when stored. This is a common myth with no scientific basis. However, there are a few important points to consider about onion storage for safety and quality.
Onions are rich in sulphur compounds, which give them their distinctive flavour and aroma. These compounds also have antimicrobial properties that help prevent the growth of harmful bacteria. However, when an onion is peeled and exposed to air, it loses its protective outer layers, making it more susceptible to contamination if not stored properly.
How to Safely Store Peeled Onions
- Refrigeration: Peeled or chopped onions should be placed in an airtight container and stored in the refrigerator at a temperature below 5°C (41°F). Under these conditions, they remain safe to eat for up to 7 days.
- Avoid Exposure: Leaving peeled onions uncovered at room temperature can lead to bacterial growth, which is where the myth of “toxicity” likely originated. While they won’t become poisonous, they may spoil more quickly, leading to off flavours or unpleasant odours.
Scientific Insights
Interestingly, onions are naturally low in moisture compared to other vegetables, which makes them less hospitable to harmful microorganisms. They also contain antioxidants, such as quercetin, that may offer health benefits, including anti-inflammatory and antibacterial properties.
Flavour and Freshness
While storing peeled onions in the fridge is safe, their flavour and texture may degrade over time due to oxidation and moisture loss. To retain their freshness, use them within 3–4 days for best results.
In summary, peeled onions can be safely stored if handled properly. By understanding the science behind their composition and following safe storage practices, you can avoid waste and enjoy their flavour in your meals.