What are betalains?

Plant pigments have widely different chemical structures. The major chemical types are chlorophylls, carotenoids, anthocyanins and betalains.

Betalains are plant derived natural pigments that are presently gaining popularity for use as natural colorants in the food industry. The growing interest of consumers in the aesthetic, nutritional and safety aspects of food has increased the demand for natural pigments such as betalains to be used as alternative colorants in food products.

The major dietary sources of betalains are not only cactus pear and red and yellow beetroot but also colored Swiss chard and grain or leafy amaranth.

The major commercially exploited betalain crop is red beetroot (Beta vulgaris) because the extract contains mainly betanin, which is approved as a red food colorant E162 in different low-acid and neutral food commodities (pH 3–7) from beverages to candies and from dairy to cattle products by both the European Union and the United States.

According to their chemical structure, betalains can be subdivided into red-violet betacyanins or yellow betaxanthins, with its color ascribed by the betalain structure's resonating double bonds.
What are betalains?