2019 Volume 20 Issue 1 Pages 13-21
This study aimed to determine and measure the presence of flavonoids and limonoids in yuzu (Citrus junos Sieb. ex Tanaka) seed oils and various commercial carrier oils. An extraction method for such compounds from oil samples was first used. A mixture of 5 g of oil sample and 5 mL of methanol-dimethyl sulfoxide (1 : 1) with naringenin as an internal standard was shaken and centrifuged to obtain the lower layer for analysis. Qualitative and quantitative determinations of flavonoids and limonoids were carried out using high-performance liquid chromatography and liquid chromatography-mass spectrometry. Flavonoids were not observed in the purified yuzu seed oil. By contrast, limonoids, such as limonin, nomilin, and obacunone, were observed at a concentration of 12.2, 3.6, and 21.3 mg/kg, respectively. Moreover, these compounds were also detected in the crude yuzu seed oil prepared at the laboratory at high concentrations of 636, 757, and 43.6 mg/kg, respectively. A total of 20 types of flavonoids and limonoids analyzed in the present study were not detected in 15 commercial carrier oils. However, nomilin and tangeretin were detected only in sesame oil at a concentration of 1,290 and 155 mg/kg, respectively. The present analytical method involving the extraction step was also applied for common oil products.
