However, green apple mostly refers to Granny Smith variety, which is also the most popular one.

There are other varieties, including:

• Crispin
• Shizuka
• Pippin

Origin

The cultivation of Granny Smith is attributed to Maria Ann Smith (and hence the name) of Sydney, Australia in 1868. Smith was a recent immigrant to Australia and had purchased an orchard which she cultivated with her husband. On throwing French crab-apple remains and apple cores in the same corner, the green apple was accidentally cultivated. Smith found these new apples delicious and good for cooking, so began to promote it. Other local planters also began to cultivate this variety and from 1895 onwards, the Australian government began to promote Granny Smith apples. Due to its longer shelf life, this  apple became popular internationally. 

Nutrition

Apples are full of fiber, phytochemicals such as quercetin, catechin, chlorogenic acid, anthocyanin, and vitamin C. The quercetin found in apples is an antioxidant and has anti-inflammatory properties, while pectin helps in lowering LDL and decreasing the risk of heart diseases. Pectin also has cancer preventing properties. Consuming green apples may keep the pancreas in good health, preventing or restricting the onset of diabetes. Eating apples on a regular basis can also help in keeping the weight in check.

One cup of sliced green apples (109g) contains:

To get the full benefits of nutrition from apples, it is best to consume them raw and whole. The removal of the skin reduces the flavonoids and the fiber, while dehydrating the green apples removes the vitamin C. 

Green apple recipes

Green apples are known as cooking apples and are used in a variety of dishes. They are great in desserts as well as in salads and sometimes, even in main course dishes. Here are a few interesting green apple recipes:

• Green Apple Curry
• Cupcakes
• Apple Crumble
• Apple Strudel
• Apple Tart

FDA regulations

The FDA describes fresh fruit as fresh produce that is sold to final consumers in an unprocessed or raw form. It regulates the production and marketing of fresh fruits, including green apples. Products made for consumption from fresh green apples, such as canned apple, apple juice, apple jam, apple butter, and other products are also covered under the FDA and are strictly regulated.

References

Harvard T.H. Chan School of Public Health, The Nutrition Source, Apples
https://www.hsph.harvard.edu/nutritionsource/foodgreen -features/apples/

Food and Drug Administration, United States of America, Guidance for Industry: Guide to Minimize Microbial Food Safety Hazards of Fresh-cut Fruits and Vegetables, FDA-2008-D-0108, 2008.
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-guide-minimize-microbial-food-safety-hazards-fresh-cut-fruits-and-vegetables