Sequential Separation of Essential Oil Components during Hydrodistillation of Azorean Cryptomeria japonica Foliage: Effects on Yield, Physical Properties, and Chemical Composition

Abstract

The hydrodistillation (HD) process is used to obtain and fractionate essential oils (EOs). In this study, we aimed to evaluate, for the first time, the effects of six different HD timeframes (HDTs: 0–2, 2–10, 10–30, 30–60, 60–120, and 120–240 min) on the yield, physical properties, and chemical profile of Azorean Cryptomeria japonica foliage (Az–CJF) EO. An Az–CJF EO obtained by a typical HD over 4 h was used as a control sample, yielding 0.82%, w/fresh weight (f.w.), and containing eighty-nine components, as determined by GC–MS. The EO fraction yield revealed a narrow range (0.06–0.18%, w/f.w.), with ca. 50% obtained within the first hour. Monoterpene hydrocarbons dominated in Fr1 and Fr2 (92 and 45%, respectively, mainly α-pinene) while oxygen-containing sesquiterpenes prevailed in Frs. 3–6 (42–62%, mainly elemol and eudesmol isomers). Furthermore, Fr2 and Fr3 were the richest in oxygen-containing monoterpenes (9 and 7%, respectively, mainly bornyl acetate) and in sesquiterpene hydrocarbons (6 and 5%, respectively, mainly δ-cadinene), while Fr4 and Fr5 had higher amounts of diterpene hydrocarbons (ca. 22% both, mainly phyllocladene) and Fr6 exhibited the highest oxygen-containing diterpenes content (4%, mainly nezukol). In addition, regression models were established to predict EO yield, HD rate, and composition (major components) for a given HDT. As a result of this study, specific EO fractions can now be targeted in Az–CJF EO by adjusting the HDT. Hence, these findings can help reduce distillation time and, thus, operating costs associated with the HD process. It can also meet specific market demands due to the differential composition of the obtained EO fractions. In turn, this contributes to increasing the commercial potential of C. japonica EO.