Extended aroma extract dilution analysis profile of Shiikuwasha (Citrus depressa Hayata) pulp essential oil

Yonathan Asikin ^a, Saki Kawahira ^a, Maeda Goki ^b, Naoto Hirose ^b, Shogo Kyoda ^c, Koji Wada ^a,*

^a Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan

^b Regional Agricultural System Section, Okinawa Prefectural Agricultural Research Center, 820 Makabe, Itoman, Okinawa 901-0336, Japan

^c Agricultural Production Corporation, Katsuyama Shiikuwasa Ltd., Katsuyama, Nago, Okinawa 905-0002, Japan

Shiikuwasha pulp is an important raw material for producing citrus essential oils. The volatile aroma composition of pulp essential oil was evaluated using gas chromatography (GC) methods, and its aroma profile was assessed using GC-olfactometry with an extended aroma extract dilution analysis (AEDA) technique in regard to alterations of odor strength and sensorial perception throughout serial dilution steps. The essential oil comprised a mixture of 55 aroma compounds, including monoterpene hydrocarbon, sesquiterpene hydrocarbon, alcohol, aldehyde, ester, and oxide compounds. The predominant compounds were limonene [57.36% (4462.80 mg/100 g of pulp)] and γ-terpinene [25.14% (1956.21 mg/100 g of pulp)]. However, linalool was identified as one of the key aroma components providing the highest flavor dilution factor in AEDA, whilst three sesquiterpene hydrocarbons (δ-elemene, germacrene B, and bicyclosesquiphellandrene) and two esters (heptyl acetate and decyl acetate) had superior relative flavor activities. The extended AEDA profile identified variations in assessed odor perceptions, intensity, and duration of aroma components over dilution, whereas the 12 most odor-active compounds showed comparable odor strengths.

Keywords: Shiikuwasha pulp essential oil, Gas chromatography-olfactometry, Extended aroma extract dilution analysis, Odor strength, Aroma profile