What makes onions red?

The red color of onions is caused by the presence of anthocyanins, which are natural pigments found in plants. Anthocyanins belong to a group of compounds known as flavonoids, which are known for their antioxidant and health-promoting properties.

In the case of onions, the specific anthocyanin responsible for their red color is called quercetin. Quercetin is a flavonol, which is a type of flavonoid. It is a water-soluble pigment that can range in color from pale yellow to deep red, depending on the concentration and pH of the solution.

The red color of onions is mainly concentrated in the outer layers of the onion bulb. This is because the outer layers are more exposed to sunlight, which stimulates the production of anthocyanins as a natural defense mechanism against UV radiation.

The red color of onions can vary in intensity depending on the variety of onion. Some red onion varieties, such as the Red Burgundy onion, have a deep, vibrant red color, while others, such as the Red Wing onion, have a milder, more pinkish-red color.

In addition to their visual appeal, the red color of onions is also associated with certain health benefits. Anthocyanins are known to have antioxidant and anti-inflammatory properties, and they have been linked to various health benefits, including reduced risk of heart disease, cancer, and certain neurodegenerative disorders.