<P> The nutritional value of banana peel depends on the stage of maturity and the cultivar; for example plantain peels contain less fibre than dessert banana peels, and lignin content increases with ripening (from 7 to 15% dry matter). On average, banana peels contain 6 - 9% dry matter of protein and 20 - 30% fibre (measured as NDF). Green plantain peels contain 40% starch that is transformed into sugars after ripening . Green banana peels contain much less starch (about 15%) when green than plantain peels, while ripe banana peels contain up to 30% free sugars . </P> <P> Banana peels are also used for water purification, to produce ethanol, cellulase, laccase, as fertilizer and in composting . </P> <P> Banana peel is also part of the classic physical comedy slapstick visual gag, the "slipping on a banana peel". This gag was already seen as classic in 1920s America . It can be traced to the late 19th century, when banana peel waste was considered a public hazard in a number of American towns . Although banana peel - slipping jokes date to at least 1854, they became much more popular, beginning in the late - 1860s, when the large - scale importation of bananas made them more readily available . Before banana peel jokes came into vogue, orange peels, and sometimes peach skins, or fruit peels / peelings / or skins, generally, were funny, as well as dangerous . Slipping on a banana peel was at one point a real concern with municipal ordinances governing the disposal of the peel . </P> <P> The coefficient of friction of banana peel on a linoleum surface was measured at just 0.07, about half that of lubricated metal on metal . Researchers attribute this to the crushing of the natural polysaccharide follicular gel, releasing a homogenous sol . This unsurprising finding was awarded the 2014 Ig Nobel Prize for physics . </P>

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