Onions stink due to a chemical change from alliin to sulfur compound
The onion family is large and diverse, containing more than 500 species. With such a wide range of species, the origins of the modern (or globe) onion are a bit fuzzy. It has not one, but five possible wild plants that it could have evolved from, all of which grow in the central Asian region.
Bulbs of the onion family are thought to have been used as a food source for millennia. Traces of onion remains were found alongside lateral fig and date stones dating back to 5000 BC in Bronze Age Palestinian settlements. It would be pure conjecture to suggest that these were cultivated onions. Archaeological and literary evidence suggests that cultivation probably took place around two thousand years later in ancient Egypt. This happened along with the cultivation of leeks and garlic and it is believed that the slaves who built the pyramids were fed radishes and onions.
“…It is believed that the slaves who built the pyramids were fed radishes and onions.”
It may not be surprising that it was the Romans who introduced the onion family to Europe. The origins of his name are also Roman or at least Latin. The late Latin name unio was used to describe a species of onion that resembles a single white pearl. Later the base was formed for the French, ‘Oignon’ and then, later, the English, ‘Onion’.
Why does the onion family smell? All plants closely related to onions (leeks, shallots, garlic, chives, etc.) contain thioallyl compounds or alliins. When cut or crushed, the alliin (an amino acid) within the garlic or onion is converted by an enzymatic reaction to allicin, which quickly breaks down into sulfur compounds. Sulfur compounds are aromatic and this is what gives all plants in the onion family their distinctive smell. So to put it simply:
o The onion family stinks due to a chemical change from alliin to sulfur compounds and sulfur stinks.
Health and Nutrition of the Onion Family:
Garlic contains by far the highest concentration of alliins and has been used medicinally for centuries and as an antiseptic since classical times. The Romans often used garlic and drank a solution of around 5-10 bulbs boiled in a small bucket of wine to cure a hangover.
Alliins have also been found to prevent the growth of malignant cells. In other words, they are anticancer and can help prevent the growth of cancer cells in animals. It has been documented that in areas of high garlic and onion consumption, rates of stomach cancer are relatively low.
There is increasing evidence that all members of the onion family have a positive effect in reducing the incidence of heart disease. Trials in the mid-1990s showed a drop in a test group’s cholesterol levels when given garlic powder.
It would seem that onions play a much more important anticancer or cardioprotective role than a nutritional one (see below). However, they add a distinctive taste, smell, and texture to many foods and form the starting stage in many recipes.
(All medium size), Raw Onion, Fried Onion in Oil, Pickled Onion
Energy (Kcal) 54 66 4
Protein (g) 1.8 0.9 0.1
Carbohydrate (g) 11.9 5.9 0.7
Sodium (mg) 5 2 68
Calcium (mg) 38 19 3
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I planted a few sets of onions in August for winter growth; they should be ready in late spring or early summer. These are the first onions I have ever grown as I have always been able to buy them cheap in bulk at a nearby Indian grocery store. However, this year there are only three of us in our house and I discovered that big bags are a false economy. Most of the time they sprouted or died before he had a chance to eat them all.
In addition to my sets of onions sown in August, I will be growing some from seed in January indoors for planting in April and some from seed outdoors in March. They can also be planted in sets in spring, which will be ready in late August or early September.
The soil must be well prepared for growing onions. Clay soils must be worked in a fine tillage working in abundant organic matter. It may be an idea to prepare the ground before using a green manure such as clover or phacelia. I have planted a patch of phacelia for this very reason, ideally it should be planted between March and September, but if planted in early October it should grow a bit before winter comes.
Most seed packets will give you an idea of planting depth and spacing. I always try to imagine what the plant will look like when it matures and give it a little more room than that. So each onion will be planted about 2 ½ onion sizes from its neighbor. This seems to work with most crops, but they can choke each other if they are too close together, as the roots need a certain amount of room to grow.