The Composition of Volatile Aroma Components, Flavanones, and Polymethoxylated Flavones in Shiikuwasha (Citrus depressa Hayata) Peels of Different Cultivation Lines

Abstract

Citrus peels are important sources of various pleasant aroma compounds and valuable bioactive substances. To investigate differences in the composition and content of Shiikuwasha (Citrus depressa Hayata) peels from different cultivation lines, the composition of volatile aroma components, flavanones, and polymethoxylated flavones (PMFs) in four Shiikuwasha cultivation lines was examined. The composition of volatile aroma components in cold-pressed extracts of Shiikuwasha peels was analyzed using gas chromatography-flame ionization detection and gas chromatography-mass spectrophotometry. The extracts contained mainly monoterpene hydrocarbons (93.40-97.25%), including limonene (46.52-68.26%) and γ-terpinene (21.48-30.52%). Differences in the composition of volatile aroma compounds in the Shiikuwasha cultivation lines were revealed using principal component analysis. Additionally, the composition of flavanones and PMFs was determined using high-performance liquid chromatography methods. Neohesperidin (96.58%) was the predominant flavanone in 'Izumi kugani' peel, while the other peels had high hesperidin contents (89.26-98.66%). Moreover, the PMFs of Shiikuwasha peels were composed of nobiletin (56.74-64.77%) and tangeretin (23.17-34.70%).

Effect of cultivation line and peeling on food composition, taste characteristic, aroma profile, and antioxidant activity of Shiikuwasha (Citrus depressa Hayata) juice

“…These trends might also be related to the flavonoid composition of the fruit peels. A previous study has reported that ‘Izumi kugani’ peel contains a larger amount of total flavonoid content and distinctive flavanone composition owing to the presence of neohesperidin compound, whereas peels of other Shiikuwasha cultivation lines had high hesperidin contents . Neohesperidin reportedly has greater radical‐scavenging abilities compared with those of hesperidin …”

“…‘Izumi kugani’ juice was relatively more astringent and acidic bitter, whereas ‘Kaachi’ juice had the opposite taste values. Flavonoid content and composition in the fruits might have affected the occurrence of these aftertastes; whereas a previous study has reported that the peel part of ‘Izumi kugani’ fruit has a flavonoid content greater than that in three other cultivation lines . Moreover, it had a distinctive amount of neohesperidin, whereas other Shiikuwasha cultivation lines contained its flavanone glycoside isomer, hesperidin.…”

“…The isolated volatile aroma extract was then analyzed using gas chromatography-flame ionization detection-mass spectrophotometry (GC-FID-MS) following a previous method. 1 The composition of volatile aroma components was examined using an Agilent 6890 N gas chromatograph equipped with a bonded-phase fused silica capillary column (DB-Wax, 60 m × 0.25 mm i.d., film thickness 0.25 μm, Agilent J&W, Santa Clara, CA, USA) and a flame ionization detector. The gas chromatograph injector and the flame ionization detector were both set at 250 • C. Samples (1 μL) were injected using split mode injection (1:50) under a helium atmosphere.…”

“…Shiikuwasha is characterized by small fruit (weight, 26–45 g; polar diameter, 29–35 mm; equatorial diameter, 41–46 mm) with a thin, yellowish‐green peel approximately 1.6 mm thick. The peel is rich in flavonoid components, particularly flavanones and polymethoxylated flavones, and strong aroma characteristics . Ripe fruit of Shiikuwasha is commonly harvested during winter from November to December and processed into food products such as beverages, confectionery, and additives, which are regarded as national products of Japan.…”

“…The peel is rich in flavonoid components, particularly flavanones and polymethoxylated flavones, and strong aroma characteristics. 1 Ripe fruit of Shiikuwasha is commonly harvested during winter from November to December and processed into food products such as beverages, confectionery, and additives, which are regarded as national products of Japan. Shiikuwasha juice is also abundant in flavonoids that have hepatoprotective activity against D-galactosamine-induced liver injury.…”