Onions usually germinate in a relatively humid environment. In this case, harmful substances such as solanine will not be produced like potato germination, so eating germinated onions will not cause physical harm. Only after the onion germinates, the content, proportion and taste of nutrients have changed.

However, in a humid environment, onions are prone to mildew while sprouting, which needs careful observation to eliminate this situation. If you eat sprouted and moldy onions, it will easily lead to poisoning, especially many molds, such as Aspergillus flavus, which can secrete aflatoxin and is a highly pathogenic substance.

Onion is a perennial herb of Liliaceae and Allium. Bulbs are thick and subglobose; Paper to thin leathery, with thick endothelium, fleshy leaves, cylindrical and hollow, thickest below the middle, narrower upward, shorter than scape, and stout scape.

Umbellies are spherical with many dense flowers; Pollen white; Tepals have green midvein, oblong-ovoid, filaments of equal length, nearly spherical ovary, and concave honey holes with curtains at the base of abdominal suture; Flowering and fruiting in May-July. Purple onion is rich in anthocyanins, and the contents of protein, dietary fiber, calcium, magnesium, zinc and iron are higher than those of yellow onion and white onion, but the contents of carotene and vitamin C in the latter two are higher than those of purple onion.

In terms of taste, white onion is sweet, tender and high in moisture, suitable for fresh eating, baking or stewing. Yellow-skinned onion tastes slightly sweet and spicy, which is suitable for eating raw or dipped in sauce. Purple onion tastes the hottest.