There are two types of green bananas: bananas that remain green when ripe and unripe yellow bananas. The flesh of the former is soft and tasty eaten raw. The later is starchy and tastes best when cooked.
Types of bananas that remain green when ripe:
Musa Ebun Musak - This cooking banana matures at 10 - 12 feet tall. It is hardy as far north as zone 8. The plant is green with brown in the trunk. The fruit is 4 - 6 inches long. Commonly called Crocodile Fingers.
Pisang Masak Hijau - Also called Bungulan and sometimes Monte Cristo. This tall thin plant is prone to wind damage but immune to Panama disease. Very sweet white flesh spoils quickly.
These types of bananas do change color when they ripen. They just don't turn yellow. The change is subtle. Bungulan becomes a lighter shade of green when ripe, like the color of a Granny Smith apple.
Unripe yellow bananas
If you are
yourself, it is important to wait until they reach full size before using them as immature bananas can upset your stomach. This is not a concern with store bought fruit as they are not harvested until they mature.
Apparently, mature green bananas can sooth an unsettled tummy. According to the June 30, 2009 issue of the Pediatric Infectious Disease Journal, cooked, unripe, mature banana fruit is antidiarrheal. People with inflammatory bowel diseases can benefit from adding it to their diets.
There is a recipe for green banana fries on the
Fun Facts About Bananas
page. Though this may not be the kind of dietary addition that the docs had in mind.