A green orange may sound like a contradiction in terms, but in fact there are some circumstances in which an orange can appear green in color. This unusual phenomenon has a scientific explanation behind it. In the following article, we will explore how an orange can turn green, looking at the chemistry and botany behind it. We will also examine some common scenarios that can result in green oranges, from unripe fruit to color-changing food dyes. Read on to unlock the mystery of this colorful citrus curiosity!
How Can Oranges Turn Green?
Oranges, like all citrus fruits, contain high levels of chlorophyll while growing. Chlorophyll is a green pigment present in plants that absorbs sunlight and allows photosynthesis to occur. In most oranges, the chlorophyll is overpowered by orange carotenoid pigments like beta-carotene. This is what gives oranges their familiar bright orange hue. However, there are some situations that can cause the chlorophyll to become more dominant, resulting in green oranges. Here are some of the main ways this can happen:
Unripe Fruit
One common reason for green oranges is picking the fruit before it is ripe. Unripe oranges have high levels of chlorophyll and low levels of carotenoids. As the orange matures on the tree, chlorophyll breaks down and carotenoids build up, changing the color from green to orange. If picked too early, the orange will still be green. This is often done intentionally for ornamental purposes, as some people enjoy the unique look of green oranges. However, it does affect the taste, making the oranges more sour and bitter than ripe ones.
Cold Temperatures
Cool weather can also cause oranges to turn green. Carotenoid pigments are sensitive to cold conditions. If an orange tree experiences frost or cold spells during the growing season, it can interrupt production of carotenoids, allowing the underlying green chlorophyll to show through. Oranges negatively affected by the cold will remain green even after ripening. Their flavor is also noticeably altered, becoming blander and less sweet than a normal orange.
Genetic Mutations
Some citrus trees develop genetic mutations that prevent them from producing carotenoids in their fruit. Without orange pigments, the natural chlorophyll makes the oranges stay green. Mutant varieties like the green orange and Limequat have natural genetic alterations that give them uniquely green oranges. These specially bred green oranges have a distinct flavor different from normal oranges, with a hint of lime or citron taste.
Artificial Coloring
In some cases, plain green food dye is used to create green oranges artificially. This is sometimes done for festive occasions, novelty recipes, or to visually distinguish different Orange variants. The food coloring only changes the outer appearance of the peel. It does not affect the inner fruit or orange flavor. However, dyeing chemicals can occasionally seep through the rind and alter the taste if left on too long.
Common Causes of Green Oranges
Now that we’ve looked at the ways oranges can turn green, let’s examine some specific scenarios that often produce green oranges. Here are some of the most common causes you might encounter:
Picked from the Tree Too Early
As mentioned, picking unripe green oranges directly from the tree is a straightforward route to green oranges. Many people actually prefer the tangy, sour flavor of unripe oranges. Green oranges also last longer in storage compared to ripe oranges. However, the maturity needs to be carefully monitored for the best results.
Premature Harvest After Cold Snap
If temperatures drop close to harvest time, growers may pick oranges while they are still green to avoid further cold damage. The oranges will not be able to ripen properly after being chilled, so they are picked while still green. This results in green oranges on the market.
Imported from Cold Climates
Oranges imported from cooler northern regions are more prone to being green. The carotenoid development can be hindered by the colder climate. Even after artificially turning orange through ethylene gas ripening, imported oranges may revert to a greenish tinge, especially around the stem.
Dyed for Decorations
As a novelty for holidays or events, plain green food coloring is sometimes painted directly onto orange peels. This instantly gives the appearance of a green orange, though it only affects the exterior color. It has no impact on the inner flesh or taste unless left to seep for too long.
Green Orange Varietal
There are a few specialty citrus varietals that naturally produce green oranges due to genetic factors. The green orange is one example, with dark green rinds and greenish internal flesh. Limequats are another cross-bred variety resulting in green fruits. These varietals provide an unusual alternative flavor to regular oranges.
Characteristics of Green Oranges
So what should you expect if you cut open a green orange? Here are some of the notable characteristics of green oranges:
External Color
The external rind of a green orange is most commonly a light greenish-yellow or darker forest green. It may have yellowish undertones, greenish patches, or even mixed blotches of green and orange. The intensity of the green color varies based on the specific cause.
Internal Color
Inside, the membranes and juice vesicles (segments) are often tinged with yellowish-green. In fully green varietals, the inside flesh is darker green. The juice itself is typically a golden or greenish color rather than true orange.
Flavor
Green oranges are more tart and acidic than ripe oranges. They have a characteristically sour, bitter bite. Some describe the taste as astringent or herbaceous with perhaps piney or grassy undertones from the chlorophyll. Sugar content and sweetness will be lower.
Aroma
The smell of greens oranges is weaker than ripe oranges, often with a more vinegary or citrusy tart scent. The citrus oils that give fresh oranges their tangy aroma are not as fully developed.
Texture
Unripe green oranges have a firm, dense flesh. As they ripen, the texture softens and becomes juicier. But green oranges maintain a chunky, chewy flesh even when the skin softens. The membranes are often quite bitter and resinous.
Are Green Oranges Safe to Eat?
Green oranges are safe to eat, provided they are tree-ripened or artificially dyed. However, unripe picked green oranges or those chilled on the tree may potentially cause digestive upset if consumed in excess. The higher acids and bitter compounds can be hard to digest. As with any food, moderation is key. Here are some guidelines for safely enjoying green oranges:
– Avoid very firm, pale oranges, which are likely extremely unripe.
– Start with small portions to test digestibility.
– Peel and eat segments whole to avoid biting into bitter membranes.
– Add sweeteners or spices to balance the sour taste.
– Dilute juice with water or blend into recipes providing sweetness.
– Use external peel for zest, avoiding any internal pith.
– Cook into recipes to mellow the sourness, like marmalade.
– Enjoy the novelty color, but accompany with sweeter oranges.
With proper care and preparation, both the flesh and peel of green oranges can be consumed and enjoyed. The refreshing tartness pairs well with sweeter ingredients in various dishes and drinks.
How to Ripen Green Oranges
If you end up with unripe green oranges, there are ways to ripen them at home. Here are some tips for turning green oranges orange:
– Leave at room temperature in a sunny spot to naturally ripen. Check daily for softness.
– Place inside a paper bag with an apple or banana to accelerate ripening with ethylene gas.
– Warm briefly in a 200°F oven to stimulate carotenoid development, then let sit on counter.
– Wrap in a newspaper and store for 1-2 weeks to slowly deepen orange color over time.
– Scrub outer peel with a dry brush to help break down chlorophyll.
– Soak in salty water for 1 hour to draw out bitterness, rinse, and air dry.
– Squeeze juice and strain out membranes and pulp to mellow the acidic taste.
– Use lime or lemon juice to make the flavor more palatable.
With patience and experimentation, an unripe green orange can mature into a sweet, juicy orange at home. But flavor and texture may still differ from a tree-ripened fruit.
Uses for Green Oranges
Rather than trying to ripen them, you can take advantage of the unique properties of green oranges in the kitchen. Here are some suggested uses:
Juice
Extract tart juice to mix into cocktails, salad dressings, marinades, or anywhere you want a citrus kick. Combine with sweeter orange juice to mellow it.
Zest
Grate the outer rind to release aromatic oils without bitterness. Use sparingly to add flavor to baked goods, sauces, and roasted vegetables.
Marmalade
Cook sliced green oranges into chunky marmalade, balancing out the sourness with sugar or honey.
Pickling
Pickle peeled segments or spiralized strands in brine for a fun condiment to pair with rich meats or cheese.
Decorative Displays
Arrange whole green oranges in centerpieces, wreaths, garlands, or holiday displays for their natural ornamental beauty.
Sour Candy
Dice very firm green oranges and coat in sugar or citric acid for homemade sour candy.
With creativity in the kitchen, the tartness and vibrant color of green oranges can be embraced to make delicious culinary creations.
Nutrition of Green Oranges
Green oranges are just as nutritious as ripe oranges, if not more so in some vitamins and minerals. Here is how the nutrition compares:
| Nutrient | Green Orange | Ripe Orange |
|---|---|---|
| Vitamin C | 80% DV | 70% DV |
| Folate | 15% DV | 10% DV |
| Potassium | 10% DV | 10% DV |
| Vitamin A | 2% DV | 2% DV |
– Excellent source of vitamin C. More in green oranges than ripe.
– Good source of folate. Green has more than ripe.
– Provides potassium. Similar amounts in both.
– Low in vitamin A. Carotenoids increase as orange ripens.
So green oranges can be enjoyed as a nutritional snack or ingredient. The higher acid and bitter taste results from natural plant compounds that provide many benefits.
Storage of Green Oranges
To get the most longevity and optimal eating quality out of green oranges:
– Store loose at cool room temperature, not in fridge. Cold damages flavor.
– Place green oranges by themselves, separated from ripe fruit. They give off ethylene gas.
– Use within 2 weeks for peak quality. Green oranges don’t store as long as ripe.
– Check frequently for mold growth in humid conditions. Wipe down to control.
– If drying out, wrap loosely in plastic or place in breathable paper bag.
– Avoid storing in sealed plastic, which traps moisture and accelerates spoilage.
– Refrigerate cut or juiced green oranges right away, using within 4-5 days.
With proper storage conditions, green oranges can retain their unique tart quality for up to 2 weeks post-harvest.
Conclusion
While green oranges are an unconventional citrus sight, their existence has a logical explanation. The residual green chlorophyll pigment can be revealed in certain circumstances during orange growth and ripening. Cool temperatures, early harvesting, mutations, and food dyes are some factors that can result in green oranges. These tart, acidic fruits are edible and nutritious when handled properly, though the flavor profile differs substantially from sweet, ripe oranges. Green oranges can be enjoyed for their sour enhancement to recipes, decorative appeal, or novelty snack. With some care and creativity, the green orange can provide an unexpectedly fresh and fun ingredient.
