Tannins
Tannins are the main antinutritional factors of bananas and are mostly contained in the peels. Ripening causes those tannins to migrate to the pulp or to be degraded by polyphenol oxidases and peroxidases (Happi Emaga et al., 2011). In addition to their antinutritional effects, particularly in monogastrics, banana tannins are responsible for the astringent taste of immature fruits, making them less palatable than mature fruits (Ly, 2004).
Mycotoxins
In 1986, cases of mycotoxin contamination due to Fusarium were reported in banana fruits grown in India (Swamy, 2009).
Pesticides
As bananas are subject to heavy pesticide applications, feeding animals with banana fruits or stalks may result in toxic residues in animal tissues. An Australian survey assessing 28 banana pesticides reported that carbaryl, chlorothalonil, dicofol and prochloraz could be responsible for residue violations in meat and edible offal (MacLachlan, 2006).