Once a mere waste product, the banana peel has become a source of nutrients, an animal feedstock and a fertilizer. Bananas are the second most popular fruits consumed in the United States. The banana plant is large herb -- a member of the Musaceae family – that originated in tropical southern Asia. It grows to a height of between 6 and 20 feet. In modern times, it is the foremost fruit cultivated in tropical regions worldwide.
Organic matter is the peel's principal constituent. Proteins account for 0.9 percent by weight of the peel, lipids are 1.7 percent, carbohydrates are 59.1 percent and crude fiber is 31.7 percent. This composition makes the peel a good animal feedstock.
The water, or moisture, content of banana peels depend on the time of harvesting and ripening of banana fruit. It varies between 6 and 8 percent by weight of the peel.
Potassium is the mineral with the highest concentration, comprising 0.078 percent by weight of the peel, according to studies by Nigerian scientists. Potassium regulates body fluids and blood pressure. Manganese has a slightly lower concentration in the peel, with 0.076 percent. This mineral aids bone and cartilage formation. The calcium concentration is 0.019 percent, sodium is 0.024 percent and iron is 0.00061 percent. The presence of trace amounts of phosphorus together with the potassium make banana peels an excellent garden fertilizer.
When heated, the organic content of banana peels breaks down to its constituent carbon and gases to produce banana charcoal. The product originated in Uganda to substitute dwindling wood supplies as a cooking fuel.
Pectin is a gelling agent used in jam and confectionery production. It is sourced mostly from citrus fruit and apples. Banana peels contain a smaller amount of pectin than citrus fruits but more than sugar beets.
Anti-nutrients are substances that are poisonous to humans and animals. Hydrogen cyanide concentration in a banana peel is 0.0013 percent by weight and well within the safety limit. Oxalates, which cause kidney diseases, are present at a low, safe level of 0.00051 percent. Saponins have a high 24 percent concentration. These compounds can cause paralysis of the sensory system and inhibit growth in swine and poultry. The saponin content must be removed if the peel is destined for animal feed.
Dried banana peels have 30 to 40 percent tannin content. This substance is used to treat and blacken leather. Fresh banana peels are an efficient shoe polisher.