Feijoa is an aromatic fruit and the essential oil from feijoa peel could be a valuable by-product in the juicing industry. An initial comparison of the essential oil extraction methods, steam-distillation and hydro-distillation, was conducted. The volatile compounds in the essential oils from four feijoa cultivars were identified and semi-quantified by GC-MS and the aroma active compounds in each essential oil were characterized using SPME-GC-O-MS. Hydro-distillation, with a material to water ratio of 1:4 and an extraction time of 90 min, was the optimized extraction method for feijoa essential oil. The Wiki Tu cultivar produced the highest essential oil yield among the four selected cultivars. A total of 160 compounds were detected, among which 90 compounds were reported for the first time in feijoa essential oils. Terpenes and esters were dominant compounds in feijoa essential oil composition and were also major contributors to feijoa essential oil aroma. Key aroma active compounds in feijoa essential oils were α-terpineol, ethyl benzoate, (Z)-3-hexenyl hexanoate, linalool, (E)-geraniol, 2-undecanone, 3-octanone, α-cubebene, and germacrene D. This is the first report on the optimization of the extraction method and the establishment of the aroma profile of feijoa essential oils, with a comparison of four New Zealand grown cultivars.
Keywords: GC-MS; HS-SPME-GC-O-MS; aroma active compounds; aroma profile; feijoa essential oil; hydro-distillation.