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Effect of size grading on the essential oil yield and composition of fresh ginger rhizomes
Abstract
The essential oil of freshly harvested 12 months mature ginger rhizomes graded based on their thickness, according to three commonly occuring sizes (big, medium and small) were extracted and
subjected to GC-MS evaluation, in order to establish likely variation in yield and identify possible compositional differences between the
three ginger grades. Results revealed that the essential oil yield were found to be size dependent, and had inversely proportional relationship to rhizome thickness, (big 3.2±0.148%, medium 4.1±0.489% and small 5.1±0.208%), with 28-59% yield variation among the grades. The result obtained from gas chromatographic and mass spectrometric analyses showed that the concentration of essential oil constituents of ginger decreased with increase in size. The major constituents detected included different levels of á-gingiberene, â-Sesquiphellandrene, â-Bisabolene, Ar-curcumene, â-Phellandrene, Camphene, Geraniol, á- Farnesene and Neral, which were significantly different from each size grade (P<0.01). The concentration of the essential oil constituents were highest in small rhizomes followed by medium and big rhizomes. It is evident from this study that the essential oil yield and compositional characteristics of the three ginger size grades vary from each other, and would assist product developers in optimizing their selection of
appropriate ginger rhizomes for use in product formulation.
subjected to GC-MS evaluation, in order to establish likely variation in yield and identify possible compositional differences between the
three ginger grades. Results revealed that the essential oil yield were found to be size dependent, and had inversely proportional relationship to rhizome thickness, (big 3.2±0.148%, medium 4.1±0.489% and small 5.1±0.208%), with 28-59% yield variation among the grades. The result obtained from gas chromatographic and mass spectrometric analyses showed that the concentration of essential oil constituents of ginger decreased with increase in size. The major constituents detected included different levels of á-gingiberene, â-Sesquiphellandrene, â-Bisabolene, Ar-curcumene, â-Phellandrene, Camphene, Geraniol, á- Farnesene and Neral, which were significantly different from each size grade (P<0.01). The concentration of the essential oil constituents were highest in small rhizomes followed by medium and big rhizomes. It is evident from this study that the essential oil yield and compositional characteristics of the three ginger size grades vary from each other, and would assist product developers in optimizing their selection of
appropriate ginger rhizomes for use in product formulation.
