Anthocyanin

Anthocyanin-rich tomatoes are also called ‘blue’ tomatoes, based on their blue (unripe) skin colour. The skin colour of most Anthocyanin-rich tomatoes turns from blue/purple (unripe) to red skin with blue/purple shoulders when ripe. The level of Anthocyanin in ‘blue’ tomatoes varies widely, but some cultivars can have levels similar to grapes or black currants. Fruit size is important when considering Anthocyanin levels, because smaller tomatoes will have higher Anthocyanin levels than larger tomatoes. This is because most Anthocyanin is found in the tomato skin (rather than the flesh) and sunlight hitting the skin is what regulates Anthocyanin production. In addition, Anthocyanin or blue tomatoes might be ‘water-wise’ tomatoes. The University of California Master Gardener Program of Sonoma County (an area which experiences drought conditions) notes that: “Varieties with the unusual blue color that comes from the pigment anthocyanin blocks the sun, protects the fruit, and may result in lower need for irrigation.”