Question: Why are some fruits and vegetables yellow and orange?
About the article "Vegetable", section "Color pigments".

Candidate passages:
The orange color of carrots, pumpkins, sweet potatoes, oranges, melons and many other fruits and vegetables comes from carotenes, a type of orange photosynthetic pigment.
This pigment transmits the light energy that the plants absorb from chlorophyll.
Before the 18th century, carrots from Asia were usually purple, while those in Europe were either white or red.
Dutch farmers bred a variety that was orange; according to some sources, as a tribute to the King of the Netherlands, William of Orange.
The long orange Dutch carrot, first described in 1721, is the ancestor of the orange horn carrot, one of the most common types found in supermarkets today.
It takes its name from the town of Hoorn, in the Netherlands. 
The green color of leaf vegetables is due to the presence of the green pigment chlorophyll.
Chlorophyll is affected by the pH, and it changes to olive green in acid conditions, and to bright green in alkaline conditions.
Some of the acids are released in steam during cooking, particularly if cooked without a cover.
The yellow/orange colors of fruits and vegetables are due to the presence of carotenoids, which are also affected by normal cooking processes or changes in pH.
The red/blue coloring of some fruits and vegetables (e.g., blackberries and red cabbage) are due to anthocyanins, which are sensitive to changes in pH.
When the pH is neutral, the pigments are purple, when acidic, red, and when alkaline, blue.
These pigments are quite water-soluble.
This property can be used in rudimentary testing of pH.
β-carotene contributes to the orange color of many different fruits and vegetables.
Vietnamese gac ("Momordica cochinchinensis" Spreng.)
and crude palm oil are particularly rich sources, as are yellow and orange fruits, such as cantaloupe, mangoes and papayas, and orange root vegetables such as carrots and yams.
The color of β-carotene is masked by chlorophyll in green leafy vegetables such as spinach, kale, sweet potato leaves, and sweet gourd leaves.
Vietnamese gac and crude palm oil have the highest content of β-carotene of any known plant source, 10 times higher than carrots, for example.
However, gac is quite rare and unknown outside its native region of Southeast Asia, and crude palm oil is typically processed to remove the carotenoids before sale to improve the color and clarity.
The average daily intake of β-carotene is in the range 2–7 mg, as estimated from a pooled analysis of 500,000 women living in the USA, Canada, and some European countries.
The U.S. Department of Agriculture lists the following 10 foods to have the highest β-carotene content per serving. 
In countries such as the UK and Australia, Campbell's also makes V8 100% Fruit & Vegetable Juice, combining vegetable juice with fruit juices for one serving of vegetables and one serving of fruits.
This is available elsewhere as V8 V-Fusion.
They are also sold in "light" versions containing 50% juice (1/2 serving of vegetables and 1/2 serving of fruits) with added flavors to reduce calorie content.
V8 V-Fusion + Tea was recently introduced.
It contains a 1/2 serving of vegetables and a 1/2 serving of fruits.
Some varieties are composed of: Strawberry Banana: Sweet Potatoes, Tomatoes, Carrots, Beets, White Grapes, Oranges, Apples, Strawberries, Bananas and Banana Puree.
Pomegranate Blueberry: Sweet Potatoes, Purple Carrots, Tomatoes, Carrots, Apples, White Grapes.
Tropical Orange: Sweet Potatoes, Carrots, Yellow Tomatoes, Squash, White Grapes, Oranges, Pineapples.
Peach Mango: Sweet Potatoes, Yellow Tomatoes, Squash, White Grapes, Oranges, Peaches, Mangoes.
Acai Mixed Berry: Sweet Potatoes, Carrots, Apples, White Grapes, Acai Berries, Blueberries, Limes.
Cranberry Blackberry: Sweet Potatoes, Purple Carrots, Carrots, Apples, White Grapes, Cranberry, Blackberry, Lemon Juice.
Goji Raspberry: Sweet Potatoes, Purple Carrots, Carrots, Apples, White Grapes, Cherries, Strawberries, Blackberry, Oranges, Goji, Red Raspberry, Lemon Juice.
The Australian flavour variants are Tropical, Melon Burst, Citrus Splash, Apple, Carrot & Ginger, and Apple Plum Fusion.
Other varieties include V8 Splash. 
The diet of the eclectus in the wild consists of mainly fruits, wild figs, unripe nuts, flower and leaf buds, and some seeds.
Two favorite fruits are the pomegranate and the papaya (pawpaw) with seeds.
In captivity, they will eat most fruits including mangos, figs, guavas, bananas, any melons, stone fruits (peaches etc.
), grapes, citrus fruits, pears and apples.
The eclectus has an unusually long digestive tract and this is why it requires such a high fiber diet.
In captivity the eclectus parrot does benefit from a variety of fresh fruits and vegetables, leafy greens such as endive and dandelion, as well as a variety of seeds, including spray millet, and a few nuts such as shelled almonds and shelled walnuts.