The pigmentation changes that occur.

This pigmentation change does not affect the nutritional effect of the two foods, and will not produce a reaction can be safely eaten. Onions are rich in nutrients, fat-free, containing protein, sugar, crude fiber and calcium, phosphorus, iron, selenium, carotene and eighteen kinds of amino acids.

Onion Introduction

Onion is a perennial herb of the lily family, genus Allium. Bulb thick, nearly globose; papery to thin leathery, inner skin fat, fleshy, leaf blade cylindrical, hollow, the thickest below the middle, tapering upward, shorter than the scape, the scape is stout, up to 1 m high, umbels globose, with many and dense flowers; pollen white; tepals with green midvein, rectangular-orbicular ovate, filaments of equal length, the ovary subglobose, ventral suture line at the base of the curtain with the depressed nectar pits; flowering and fruiting in May to July.

Onions are biennial or perennial herbs. Root string-like, thick green cylindrical hollow leaves, the surface has a waxy; leaf sheaths fat scale-like, crowded around the shortened stems, forming bulbs (commonly known as onion); umbels, white small flowers; capsule. The outer edge of the rhizome is covered with a thin skin (white, yellow, or red), and inside are layers and layers of flesh, usually white or yellowish.

Native to western Asia, it is widely cultivated in China and abroad. It is one of the main vegetables in China. China's onion origin mainly in Fujian, Shandong, Gansu, Inner Mongolia, Xinjiang and other places.