Polymethoxylated flavones in Brazilian orange juice

Sinensetin has been quantified in authentic samples of Brazilian orange juice. In addition, six further polymethoxylated flavones (PMFs) have been determined in terms of their relative amounts. The PMFs were extracted into toluene and analysed using reversed phase HPLC with detection at 340 nm. Peak identification was based on the UV-visible spectra and the elution order described in the literature. Hand-squeezed orange juices contained a mean of 0.10 (SD 0.04) mg(-1) sinensetin with the highest concentrations found in Pera and Natal varieties. Commercial samples of frozen concentrated orange juice (FCOJ), frozen concentrated pulp-wash (FCOPW), retail FCOJ and retail freshly squeezed orange juice (FSOJ) typically contained at least ten times more sinensetin than those found for samples squeezed by hand. The PMFs peak area ratios for these sample classes were examined further using canonical discriminant analysis. This procedure could distinguish the hand-squeezed juices of Pera and Hamlin varieties from those of Natal and Valencia. Similarly, hand-squeezed juices could be readily distinguished from the commercial samples of FCOJ, FCOPW, retail FCOJ and retail FSOJ. (C) 1998 Elsevier Science Ltd. All rights reserved.