Can you boil onions? (+1 Reason you should)

In this article, we will answer the question “can you boil onions?” and discuss what happens when you boil onions, how to boil onions, as well as the best methods to cook onions.

Can you boil onions?

You can boil onions. Boiling onions is a good way to prepare onions and then adding them to any recipe of your choice. 

Boiling onions is a simple method to cook vegetables, which, in addition to reducing the microbial load and improving the safety consumption of vegetables, can soften the tissues and reduce the intensity of the onion flavor.

However, boiling can also lead to nutritional losses, especially concerning the vitamin C and flavonols in onions (1,2). 

What happens when you boil onions?

When you boil onions, several changes occur in the onion, including (1,2,3):

Onions contain many flavonols, which are antioxidant compounds. One of the most important flavonol in onions is quercetin, which is related to several health benefits of onions. 

When onions are boiled, quercetin and other water soluble compounds are leached into the water, resulting in the significant loss of this compound in the onions. Studies report that, although losses by thermal destruction are negligible, the losses when boiling onions is between 30 to 48%. 

Similarly, onions contain vitamin C, which is an important vitamin for maintaining health due to its antioxidative property. Vitamin C, in addition to being water soluble, is thermally unstable and destroyed by heat. 

In this way, cooking onions by boiling and other methods result in the significant loss of vitamin C. A study showed that boiling onions led to about 54% loss of this vitamin.

Boiling onions also has positive consequences, because boiling can improve the extraction, the digestibility and bioavailability of the nutrients in onions. Cooking by boiling leads to the softening of the tissue and higher accessibility by the enzymes in the digestive process.

What are the best methods to cook onions?

There are many methods to cook onions, for instance, frying with oil or butter, steaming, boiling, baking and microwaving (1,2).

According to studies, frying onions can preserve the quercetin in onions by 80%, while there is a significant loss of vitamin C. There were no differences when frying in butter and frying in oil were compared.  

Studies report that microwaving could improve the extractability of the quercetin of onions, increasing its detectable amounts. The losses of soluble vitamins, such as from the B-complex and vitamin C could be better preserved.

This can be explained by the fact that microwaving requires no additional water and can be done by simply placing the vegetable in a microwavable bowl and covering it to be cooked for one minute (1). 

Therefore, the best cooking method to preserve the health components of raw onions is microwaving.

How to boil onions?

To boil onions, follow the instructions (adapted from 2):

  1. Clean and peel the onions
  2. Wash the peeled onions and mince them, using a food processor or a sharp knife and a cutting board
  3. Add a cup of water to a cooking pan and bring to boil
  4. Add 100 g of minced onions and cover
  5. Boil for 5 minutes at medium heat 

How to microwave onions?

To microwave onions, follow the instructions (adapted from 2):

  1. Clean and peel the onions
  2. Wash the peeled onions and mince them, using a food processor or a sharp knife and a cutting board
  3. Place 50 g of minced onions on a microwavable dish
  4. Cover with a commercial plastic food wrapper, such as of polyvinylidene chloride (PVC)
  5. Microwaved for 60 seconds using high energy imput

Conclusion

In this article, we answered the question “can you boil onions?” and discussed what happens when you boil onions, how to boil onions, as well as the best method to cook onions.

Other FAQs about Onions that you may be interested in.

How To Preserve Green Onions

What can I substitute for onion powder?

How to counteract too much onion in a recipe?

Citations

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