An HPLC-MS analysis of phenolic antioxidants in banana peel

Authors: Manthey, John; JAITRONG, SOMKIT - Burapha University

Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: 10/31/2016
Publication Date: 8/2/2017
Citation: Manthey, J.A., Jaitrong, S. 2017. An HPLC-MS analysis of phenolic antioxidants in banana peel. Proceedings of Florida State Horticultural Society. 129:181-184.

Interpretive Summary: Banana is an important food worldwide, and is a crop grown in most tropical agricultural regions. One of the important dietary factors of banana is the antioxidants that prevent cell damage. To study the antioxidants in the fruit pulp, these compounds were first studied in the fruit peel. The reason for this is the significantly higher concentrations of these compounds in the peel relative to the pulp. In the pulp, four main groups of antioxidants were detected and further studied. Knowledge of these compounds will aid in understanding the functions of banana antioxidants in improving human health and nutrition.

Technical Abstract: Banana peels are rich in many nutrients which allow for their use as food ingredients and biofertilizers in tropical agriculture. The phenomenon of rapid peel browning is a common occurrence, and is attributable to the peel’s high polyphenol oxidase activity and high concentrations of polyphenols. An analysis of methanol extracts of banana peel shows a diversity of polyphenols, including proanthocyanidin oligomers (n=1- 4) and polymers, ferulic acid and p-coumaric acid conjugates, and flavonoids. The analysis of these classes of compounds is facilitated by separations accomplished by LH20 chromatography. The flavonoids, which comprise the minor portion of polyphenols, occur mainly as flavonol glycosides, including conjugates of myricetin and quercetin. The numerous isomers of ferulic and p-coumaric acid conjugates (each n > 6) occur as high molecular weight compounds, and their mass spectra exhibit similar patterns of neutral losses, suggesting that they occur with similar side groups. Infrared and NMR spectroscopy will be used to identify the structures of these compounds. The tentative structures and degrees of polymerization of the proanthocyanidins are analyzed by electrospray ionization mass spectrometry. This is further facilitated by separations of these complexes by normal phase thin layer chromatography. This study illustrates the diversity of the polyphenols in banana peel, and is supportive of the use of this portion of the fruit as a high antioxidant food ingredient.