Onions can be found all around the world, from Asia all the way to the Americas. They are edible used by professional chefs all over the world as garnishes or as a main dish, though not very widely consumed in this way. Not just it's bulb can be eaten, it's shoots and leaves are edible as well. They have a distinctive, strong flavour and also a pungent odour that could be neutralized and sweetened by cooking or heating. It has a dry, paper-like skin and a juicy, fleshly, layered inner core.
It is used widely in schools in science laboratories due to its relatively large cell sizes. This property allows it to be easily visible under low-end optical microscopes used in school. Moreover, it is easily obtainable, hence its wide usage.
Onions are made up of 89% water and 8% to 9% soluble sugars, the rest is minerals, fats, proteins, and sulphur compounds.
The reason why onions are pungent when raw or partially cooked and sweet when fully cooked is due to the presence of sulphur. Sulphur is an atom belonging the Third period, and group 6. It has an atomic number of 16. Its molar mass is 32.065 g (5 significant figures). It is a solid at room temperature, with a lemon yellow, non-metallic appearance. It has a melting point of 115.21 degrees Celsius and a boiling point of 444.6 degrees Celsius. It has a total of 18 isotopes.
When onion cells are broken, the sulphur compounds found in the onion cells break down into other compounds when in contact with surroundings. When the sulphur compounds are broken down, the sweet aroma of the onion then could be noticed. During cooking or heating, the rate of enzymatic action is significantly increased; hence the sweetness of the onion would be achieved more quickly via heating methods. The sweet aroma is caused by the soluble sugars found in onions.
Onions have been used for thousands of years as medicine and a staple food. The Egyptians worshipped it, believing that its spherical...