Short answer
Beetroot, chard stems, amaranth and prickly pear owe their red-violet and yellow-orange colours to betalains, nitrogen-containing pigments quite unrelated to the anthocyanins in red cabbage or berries. Betalains are found only in one order of flowering plants and a few fungi, and have never been found in the same plant as anthocyanins. They hold their colour across the mildly acidic range most foods sit in, but are sensitive to heat, light and oxygen.
Betalains are built around betalamic acid, which contains nitrogen. Join it to a cyclo-DOPA unit and you get a betacyanin, red to violet; join it to an amino acid or amine and you get a betaxanthin, yellow to orange. Betanin, the main pigment of red beetroot, is a betacyanin. Anthocyanins, by contrast, are flavonoids with no nitrogen in the coloured core. The two groups look superficially similar in a red vegetable, but they are made by entirely different biosynthetic routes.
Betalains occur in plants of the order Caryophyllales — beets and chard, amaranth, spinach's relatives, cacti, bougainvillea, four-o'clocks — and in a handful of fungi. Within that order, plants that make betalains do not make anthocyanins, and no plant has been found with both, even though the two pigment classes seem to do similar jobs. Other members of the order use anthocyanins instead. This mutual exclusion is one of the cleaner patterns in plant chemistry and is why a red beet and a red cabbage respond so differently to the same kitchen treatment.
Add vinegar to beetroot and it stays red; add bicarbonate and it does not turn blue-green the way red cabbage does. Betanin is at its most stable in the mildly acidic range and much less stable in strongly acidic solutions. Its weak points are heat, light and oxygen: long boiling, especially once peeled, turns it brownish, and sliced beetroot left in light fades. Because betanin is water-soluble it bleeds out of cut beetroot, which is why beetroot is usually cooked whole and unpeeled, with its root and a little stalk left on.
Golden and candy-striped beetroot contain more betaxanthins; they bleed less red but lose colour the same way.
Concentrated beetroot juice and betanin are used to colour foods such as yoghurts, ice creams, sweets and meat substitutes, under the EU name beetroot red (E 162). Its heat sensitivity is a practical limit: it suits chilled and lightly processed foods better than products baked or sterilised at high temperature. The regulatory detail is on the food colourants page; this page is about the chemistry.
| Property | Betalains | Anthocyanins |
|---|---|---|
| Chemical family | Nitrogen-containing, from betalamic acid | Flavonoid glycosides |
| Typical foods | Beetroot, chard, amaranth, prickly pear, dragon fruit | Red cabbage, berries, red grapes, aubergine skin |
| Response to alkali | Little colour shift before degradation | Shifts to blue, green, then yellow |
| Main weaknesses | Heat, light, oxygen | pH, heat, light, oxygen, metals |
| EU colour number | E 162 | E 163 |
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
FactStrong evidence
Betalains are water-soluble vacuolar pigments of the order Caryophyllales and some fungi; betacyanins are red-violet and betaxanthins yellow to orange, and all contain betalamic acid.
FactStrong evidence
Anthocyanins and betalains have never been found together in the same plant and appear to be mutually exclusive.
Caveat: An observation across the plants studied, not a proven law; the mechanism is still investigated.
FactModerate evidence
Betanin solutions are much less stable at pH 2 than at pH 3, and betanin degraded about three times faster under fluorescent light at pH 3 than at pH 5 in the study the review cites.
FactStrong evidence
Beetroot red (betanin) is authorised as a food colour in the EU as E 162.
Source: Food colours (topic page)
Reviewed 29 September 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.