Why Is Blue Fruit so Rare?

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Fruit comes in every color from red to purple; yet blue fruit is very rare. Even blueberries are not truly blue as they have a slight purple tint.

In edible plants, two chemicals produce color: carotenoids and anthocyanins. Carotenoids produce red, orange, and yellow, while anthocyanins generates red, purple, and blue. Since both chemicals share the color red, it is the most probable hue. As a result, most fruit is red.

Additionally, leaves are green- the compliment of red. On the color wheel, red and green lay directly across from each other. This contrast makes it easy for birds and other animals to spot fruit. Animals eat the fruit and, more importantly, spread the plant’s seeds, which aids reproduction. Therefore, plants with most contrast are the most likely to survive. Moreover, certain plants may produce darker or lighter leaves. The color of fruit adjusts to the leaves to maximize contrast. For example, a plant with very dark leaves often yields brighter colored fruit, usually with a yellow tint.

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Additionally, the acidity of soil affects the color of fruit. In highly acidic environments anthocyanins generate red hues. Meanwhile, less acidity yield bluer hues.   However, red is still a prominent color, so even fruit with a strong blue tint, like blueberries, may appear slightly purple.

Acidity is measured on the pH scale from 0 to 14. 7 is neutral, anything below is acidic, and anything above is basic. Strawberries have a pH of 3.00-3.90, while blueberries have the pH of 3.85-4.50. Although both types of fruit are acidic, blueberries have a higher pH than strawberries. This means they are less acidic and, as a result, have a blue tint.

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Amazingly, blue quandong, a berry popular in Australia, has a vibrant, deep teal color. This color drastically contrasts the plant’s red leaves.

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Additional fruits and vegetables that contain anthocyanins include:

Blackberries                Blueberries

Cherries                        Cranberries

Eggplant                       Plums

Raisins                          Red apples

Red beans                    Red beets

Red cabbage               Red or purple grapes

Red onions                  Red pears

Strawberries

Fruit tarts are a refreshing, (somewhat) healthy treat for summer.  Blue and red fruit topping adds patriotic flare!

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Perfect for Independence Day!

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The tarts begin with a shortbread dough pressed into a muffin pan.

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While the crusts bake, cut the fruit into thin slices.

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Then, prepare the cream cheese and yogurt filling.  Confectioners sugar instead of granulated keeps the texture smooth and creamy.

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Generously fill each crust with the cream.

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Finally, top with fruit.

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Happy Fourth of July!

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Fruit Tarts

Crust

1/2 cup butter

1/4 cup sugar

1 cup flour

1/2 tsp salt

Filling

8 ounces cream cheese

1/2 cup plain yogurt

3/4 cup confectioners sugar

1 tsp vanilla

Topping

Strawberries

Blueberries

Preheat the oven to 350° F.

For the crust, cream the butter and sugar until light. Add flour and salt. Spoon into muffin tin and press up the sides.  Bake for 20 minutes, or until very lightly browned. Let cool.

For the filling, beat the cream cheese and sugar until smooth.  Add in yogurt and vanilla.

Spoon filling into each crust.  Top with slices strawberries and blueberries.  Serve at room temperature or cold.

Makes 6 tarts.

Straight Dope

Garden Betty

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