I want to share with you a recipe from my beloved late aunt, may she rest in peace, who passed away at the age of 97 in full mental clarity and was a vegetarian. And before the perfect pie, here is something about the nutritional value of an onion: It causes us to shed tears, but also strengthens our immune system – the onion is much more than just a salad topping.
Beyond its health value, it changes in taste and sweetness depending on the cooking method, requires proper storage conditions, and is even packed with interesting myths. So how do you store it correctly, why does it make us cry, and what are its health benefits? As a scientific advisor to the Plants Production and Marketing Board, I spoke with Moshe Saadon, a farmer who also grows onions... and here are all the answers:
Medical virtues of onions: Onions against a cold? This is not a myth at all. And our grandmothers were not wrong when they recommended combining onions with honey, or using onions in any other possible way when sick and having a runny nose. So not only against the flu, there are many antioxidants in onions that work on all levels to prevent diseases:
1. Antimicrobial properties: In a study published in Planta Medica, the antimicrobial effect of sulfur compounds found in onions, particularly allicin, was investigated. The researchers examined the antibacterial and antifungal activity of allicin in onions and found that it inhibits the growth of bacteria and fungi.
2. Quercetin content: Quercetin is an antioxidant known for its anti-inflammatory and antiviral properties. In a study from the Journal of Agricultural and Food Chemistry, they checked the quercetin content in different onion varieties and found that red onions are particularly rich in quercetin.
3. Reducing the risk of colon cancer: An epidemiological study published in the Journal of Oncology examined the connection between the consumption of vegetables from the onion and garlic family and the risk of colon cancer. The study found that increased consumption of these vegetables is associated with a reduction in the risk of colon cancer.
4. The effect of red onions on breast and colon cancer cells: A study conducted in Canada examined the effect of different onion varieties on cancer cells. The researchers found that red onions, which are rich in quercetin and anthocyanins, are particularly effective in destroying breast and colon cancer cells under laboratory conditions.
5. Diabetes prevention: In a study presented at the 97th annual conference of "The Endocrine Society", they claimed that onion extract, given together with an anti-diabetic drug containing metformin, significantly lowered blood sugar and cholesterol levels and increased the effectiveness of the drug.
Diabetic rats that received a high dose of onion extract showed a decrease of over 50% in blood glucose levels. It is important to note that despite the encouraging findings, most of these studies were conducted under laboratory conditions or on animals. Additional clinical studies in humans are needed to confirm the health effects of onions. The onion can be a very beneficial addition to the diet, but of course, it should not be seen as a substitute for established medical treatments.
The amount of sugar in onions: Onions contain 4–7 grams of sugar per 100 grams, depending on the variety – white onions contain less, red and purple onions contain a bit more sugar, mainly fructose. This is the reason why purple onions are more suitable for salads, and white onions are more suitable for cooking and soups.
Why do onions become sweet after frying? In frying, a process called caramelization occurs, in which the heat breaks down the starches and complex sugars in the onion (such as fructooligosaccharides) into simple sugars like glucose and fructose.
This process starts at a temperature of about 120°C and causes the onion to acquire a sweetish taste and a golden–brown color. By the way, this is just proof that there is not always a direct connection between the sweetness of a vegetable or fruit and the amount of sugar it contains. An onion has as much sugar as a carrot or strawberries, and you do not feel its sweetness until the pungent substances break down.
How long can you keep onions?
- Whole onion (uncut): It can be kept for about 2–3 months in a cool, dry, and dark place with ventilation (for example, in a cupboard outside the refrigerator).
- Cut onion: It must be stored in an airtight container in the refrigerator, and it will keep for about 7–10 days.
- Cooked onion: It can be kept in the refrigerator for up to 5 days.
- Frozen onion: Onion pieces can be frozen, and it will keep for about 6–8 months.
And what about keeping onions in the refrigerator? Do they become toxic? The myth regarding a cut onion in the refrigerator becoming toxic is not scientifically based!!!! Here are a few points to clarify the matter:
Can a cut onion cause poisoning? Absolutely not! There is no chemical mechanism that can cause this to happen!!! The substances in onions do not break down into toxins but simply dry out or oxidize.
Does a cut onion absorb bacteria and become toxic? No. There is no scientific proof that an onion absorbs bacteria from the air and becomes toxic, especially if you store it correctly (in the refrigerator, in an airtight container, or well–wrapped), there is no danger.
What does happen to a cut onion in the refrigerator?
- It might dry out and lose its freshness.
- It might absorb odors from other foods in the refrigerator.
- It might cause an onion smell in other foods that are in the refrigerator
and only if we do not store it correctly – it might grow mold or develop bacteria, like any other food.
Like any food – if the onion shows signs of spoilage – bad smell, slimy texture, different color – it is best to throw it away.
How is it right to store a cut onion?
In the refrigerator – in a closed container or well–wrapped in plastic wrap.
Pay attention to signs of spoilage – if there is a strange smell, soft or slimy texture, throw it away.
Why does the onion make us cry? What is the substance that causes tears?
When cutting an onion, an enzyme called alliinase breaks down sulfur compounds called sulfoxides, which create the compound that causes us to tear up, and its complicated name is Syn–Propanethial–S–Oxide. The substance is released into the air and reacts with the tears in the eyes, creating a diluted sulfuric acid that causes irritation and tears.
How to reduce tears when cutting onions? Effective tips:
- To cool the onion – putting it in the refrigerator for 30 minutes before cutting reduces the volatility of the irritating substances.
- To use a sharp knife – a sharp knife cuts the cells smoothly and reduces the release of enzymes.
- To soak the onion in water – cutting the onion under running water or soaking it in water before cutting may reduce the release of chemicals.
- To wear swimming goggles or protective glasses – well, everyone knows this, it blocks the molecules from reaching the eyes.
- To use a fan – a fan directed with the air away from the face can disperse the substance and prevent it from reaching the eyes.
And for the recipe:
Chop 4 onions.
Add a cup of whole spelt flour.
A teaspoon of baking powder.
A third of a cup of olive oil.
Half a cup of water.
2 eggs.
A teaspoon of salt, a little black pepper.
Mix, flatten on a greased pan, and bake for about half an hour at 180°C.
10 servings, 120 calories per serving. Together with a large salad – a dietetic meal.
For Dr. Maya Rosman's course: How to improve your health and how to lose weight in a sane and logical way, click here