To Örebro University

Despite the important role of total soluble phenoliccompounds (TSPC) in plant and human health, a large numberof studies that have evaluated the TSPC in food matrices didnot consider possible interfering compounds such as solublesugars, ascorbic acid (AA), and other reducing compounds inthe Folin-Ciocalteu (F-C) quantification method. Thus, thepresent study describes steps for the optimization of a meth-odology to extract the TSPC using banana leaves as an exam-ple. In addition, the method was tested using ascorbate oxi-dase (AOX) as a tool to determine and emphasize the impor-tance of the evaluation of AA interference in food productsusing orange juice as an example. The results showed that twoextraction cycles with 80 % acetone and a posterior hexaneextraction cycle to remove the excess of chlorophylls wereable to obtain a good TSPC extraction yield from bananaleaves without extracting compounds that may interfere withthe F-C method. The methodology has proven to be accurate,precise, simple, rapid, and inexpensive. Additionally, an over-estimation of the TSPC levels in AA-rich matrices was provenusing orange juice as an example. Finally, it was demonstratedthat the use of AOX could be a useful and simple tool to verifyand reduce the AA interference. This work proves and em-phasizes the importance of evaluating the yield of the extrac-tion and interferences in the quantification of the TSPC invegetal-derived foods, which are complex matrices thatshould be cautiously evaluated.