Anthocyanins are water-soluble pigments found in plants and are responsible for the colours blue, red, purple and black. They belong to a broader class of pigment molecules called flavonoids. Anthocyanins serve several functions in plants, including pollinator attraction, photoprotection and pest deterrence. In humans, they act as antioxidants and may offer health benefits. The red colours of autumn leaves come from anthocyanins.
Examples of anthocyanins and their colours
There are many anthocyanins and their derivatives. Here are some examples of anthocyanins, a list of some plants that contain them and their colour ranges. Most anthocyanins are natural pH indicators that change colour depending on whether conditions are acidic, neutral or alkaline.
| Anthocyanin | Sources | Colour |
|---|---|---|
| Cyanidin | Grapes, blackberries, blueberries, cranberries, blueberries, raspberries, apples, red cabbage | pH pH 3-11: purple pH> 11: blue |
| Delphinidin | Delphiniums, violets, Concord grapes, cranberries, pomegranates | pH pH 3-11: Purple pH> 11: Red |
| Malvidin | Primrose flowers (primrose), red wine, cranberries | acid: Red neutral: Red basic: Blue |
| Pelargonidin | Red geraniums, strawberries, blackberries, red radishes, beans | red |
| Peonidine | Peonies, roses, bluebells, blueberries, plums, black rice, black bananas | pH pH 3-5: Yellowish pink pH 5-8: Reddish purple pH> 8: Blue |
| Petunidina | Petunias, chokeberries, muscadine grapes | dark red to dark violet |
Function in plants
Plants store anthocyanins in vacuoles in all tissues, including flowers, fruits, leaves, stems and roots. The pigments serve a variety of functions:
- To attract pollinators and herbivores that disperse seeds.
- Protection against cold stress
- Deter herbivores that are attracted to the green colour.
- Allelopathy: e.g. red anthocyanin in maple leaves slows the growth of nearby saplings.
Benefits of anthocyanins
Anthocyanins act as antioxidants. in vitro e in vivo. However, scientific studies on the benefits of anthocyanins in humans show mixed results.
In 2010, the European Food Safety Authority found no evidence of an effect of anthocyanins in humans. antioxidant benefits of including anthocyanins in the diet. Anthocyanins are approved for food colouring in the European Union (colour code E163), but a 2013 study found that very little is known about their safety and toxicology to be approved as a food additive or supplement. Exceptions are the extract of skin red grape skin and blackcurrant extract, which are safe as additives. Similarly, anthocyanins are not approved food colour additives in the United States, except for grape juice, grape skin and fruit or vegetable juice.
However, some peer-reviewed studies indicate that they improve blood sugar metabolism. bloodThey help prevent high blood pressure and heart disease, improve cholesterol levels and inhibit the growth of breast cancer cells. Notable studies include a 2010 report in Nutrition Reviews on Cardiovascular Health, a 2011 study in the American Journal of Clinical Nutrition and a 2017 study in the British Journal of Pharmacology on the effect of anthocyanins in the prevention and treatment of cancer. These studies indicate the need for further research into the health benefits of anthocyanins, but nutritionists agree that brightly coloured fruits and vegetables are part of a healthy diet.
Foods rich in anthocyanins
Foods rich in anthocyanins are intensely coloured fruits, seeds and leaves in the colours black, red, blue or purple.
This table lists representative levels of various foods. Note that the levels are not exact, as they depend on the time of harvest, fruit maturity, quality and other factors.
| Food | Anthocyanin (mg per 100 g) |
|---|---|
| Bilberry | 4180 |
| Purple corn | 1642 |
| Aronia (chokeberry) | 1480 |
| Norton Grape | 888 |
| Black raspberry | 589 |
| Wild blueberry | 558 |
| Açaí | 410 |
| Raspberry | 365 |
| Grapes of Concord | 326 |
| Mora marion | 317 |
| currant | 80-420 |
| Blackcurrant | 190-270 |
| Plum Queen Garnet | 277 |
| Black bean | 213 |
| red cabbage | 150 |
| cherry | 122 |
| Blue corn (maize) | 71 |
| Black rice | 60 |
Other foods containing anthocyanins include aubergine, blueberries, violet petals, apples, peaches and black soybeans.
Not all red or purple plants get their colour from anthocyanins. For example, the colour of beetroot, cacti and amaranth comes from betalains. Plants contain either anthocyanins or betalains, not both.