**2. Microscale fractional bulb-to-bulb distillation**

200 Distillation – Advances from Modeling to Applications

which provides important information about the scent profiles of fragrant plants. The analytical advances in the latest GC-MS technology are remarkable. In testing for the presence of a particular compound, detection of trace amounts of the substance has become possible. Recently, the olfactometry (O) functionality was incorporated into the GC-MS method. That analytical method, GC-MS-O, enables the odors of each constituent in a mixture to be precisely evaluated. These advances in analytical technology are associated with the discovery of natural products with important properties, for instance, a unique flavor. However, because the level of analysis is extremely detailed, the number of components in the characteristic scent of a plant can become huge. For this reason, indentifying the important scent components out of the many components is nontrivial. As a solution, a method for measuring the relative strength of each constituent's scent has recently been developed, and key findings have been reported. However, this method has

1. As the number of components increases, the effort required for analysis becomes

2. In a mixture of multiple components with similarly strong scents, the essential

Such difficulties arise in elucidating the key fragrance constituents of essential oils obtained from fragrance materials, such as sandalwood and vetiver, which are currently used as base

We found that the fragrances of these scent materials can be expressed by combining groups of scent components. These groups consist of several organic compounds that have similar structures and thus similar odor. The interaction between these constituents is vital to the odor. From an oil, it is important to separate the *minimum odorant groups* necessary to retain

In this chapter, I will explain how to divide the odor oils from fragrant plants into groups with similar properties (structure, odor, etc.). I will also present the results of experiments

Sandalwood (*Santalum album,* L.), vetiver (*Vetiveria zizanioides*), patchouli (*Pogostemon patchouli*), and frankincense (*Boswellia papyrifera*) are typical materials in traditional Japanese incense, and the essential oils obtained from these materials possess unique and valuable features such as providing the base notes for perfume. Although many studies on the constituents of these materials have been reported, the key compounds of their scent profiles remain unknown. Determining these scent profiles is a prerequisite to elucidating the key

In attempting such a determination, however, the following main issues must be overcome. Firstly, the fragrances of the scent materials are not formed by a mere superposition of individual scents. Secondly, the scent components of these materials have weak odors. Almost all researchers have recognized these issues, but previously developed methods have not been suitable for clarifying the odor characteristics. In our work, we reconsidered and revised previous methods and were able to successfully evaluate the scent profiles of

conducted in my laboratory, which used popular and important scent materials.

the following problems.

components are difficult to identify.

the characteristic fragrance of the scent material.

components of the characteristic odors of these materials.

greater.

these materials

notes.
