The dietary information for 100 grams of Kannan pazham / banana are as follows (approximately):
75 percent water
Carbohydrates: 22.8 g
12.2 grams of sugar
2.6 grams of fiber
0.3 gram of fat
Bananas are high in carbohydrates, which appear mostly as starch in unripe bananas and sugars in ripe bananas. The carbohydrate content of bananas varies dramatically as they mature. Starch is the primary component of unripe bananas. Green bananas can contain up to 80% starch by dry weight.
The starch is transformed into sugars during ripening and amounts to less than 1% when the banana is completely ripe. Sugars found in ripe bananas include sucrose, fructose, and glucose. The total sugar content of ripe bananas can reach more than 16% of the fresh weight. Bananas have a low glycemic index (GI) of 42–58, depending on how ripe they are.
Keep bananas in a cool and dry place, and protected from the light. Keep in mind that ideally bananas are supposed to be stored at around 12 degrees celsius and if they are kept in warmer temperatures there is a chance that they will ripen quickly. If you can wrap a plastic wrapper around the stem of the banana this will help in keeping them fresh for a longer period.