Anthocyanins from banana bracts (Musa X paradisiaca) as potential food colorants

Banana (Musa X paradisiaca) bracts, abundant edible residues of banana production, were investigated as a potential source of natural colorant. Anthocyanins were extracted with acidified methanol, purified using C-18 resin, and characterized by UV-visible spectroscopy, physicochemical reactions, HPLC, and electrospray mass spectrometry. Monomeric anthocyanin content was 32.3 mg/100 g bracts on a cyanidin-3-rutinoside basis. Color characteristics (Hunter CIE L*hc) of a solution (absorbance of 0.3, 520 nm, pH 3.5), were L*=86.8, h=44.2 and c=12.7. Cyanidin-3-rutinoside represented ∼80% of the total pigment. Other anthocyanins were 3-rutinoside derivatives of delphinidin, pelargonidin, peonidin and malvidin. One acylated anthocyanin (∼2% of the pigment) was found but not identified. Acid hydrolysis of anthocyanins revealed the concomitant presence of six more common anthocyanidins (delphinidin, cyanidin, petunidin, pelargonidin, peonidin and malvidin) suggesting that, besides being a good pigment source, it could also be a useful tool for anthocyanin identification.