POLYMETHOXYLATED FLAVONES IN BRAZILIAN ORANGE JUICE

Sinensetin has been quantified in authentic samples of Brazilian orang e juice. In addition, six further polymethoxylated flavones (PMFs) hav e been determined in terms of their relative amounts. The PMFs were ex tracted into toluene and analysed using reversed phase HPLC with detec tion at 340 nm. Peak identification was based on the UV-visible spectr a and the elution order described in the literature. Hand-squeezed ora nge juices contained a mean of 0.10 (SD 0.04) mg(-1) sinensetin with t he highest concentrations found in Pera and Natal varieties. Commercia l samples of frozen concentrated orange juice (FCOJ), frozen concentra ted pulp-wash (FCOPW), retail FCOJ and retail freshly squeezed orange juice (FSOJ) typically contained at least ten times more sinensetin th an those found for samples squeezed by hand. The PMFs peak area ratios for these sample classes were examined further using canonical discri minant analysis. This procedure could distinguish the hand-squeezed ju ices of Pera and Hamlin varieties from those of Natal and Valencia. Si milarly, hand-squeezed juices could be readily distinguished from the commercial samples of FCOJ, FCOPW, retail FCOJ and retail FSOJ. (C) 19 98 Elsevier Science Ltd. All rights reserved.