Classification of fragrances

Fragrances can be broadly classified into two categories: synthetic fragrances and natural fragrances.

Natural fragrances

Natural spices are spices obtained by water steam distillation, extraction, and pressing, so the price, collection amount and quality will change, and the price of spices will fluctuate and easily become higher. For example, muscone ((R)-3-methylcyclopentadecanone), a natural spice obtained from male musk deer, has been treated as a rare spice because of its unique aroma and rarity. In order to obtain musk, people once hunted musk deer to the brink of extinction, and then the Washington Treaty was introduced to restrain and control the hunting behavior. As a result, musk, a natural fragrance, is mostly obtained through synthesis.

Synthetic fragrances

Synthetic fragrances are stable in terms of production, aroma and quality, so prices are not very volatile and are low. There are 500 major synthetic fragrances, and more than 3,000 if you include the smaller ones. The variety of synthetic fragrances produced now greatly exceeds that of natural fragrances.

There are other uses of fragrances, roughly divided into the flavor of the food we eat (food spices, spices) and perfume, flower perfume, detergent aroma, etc. (cosmetic fragrances, perfumes) these two categories. The market size of these two categories of fragrances is about the same in the world, but Japanese fragrance companies are focusing on the former.

Properties of fragrance compounds

What kind of compounds can be used as fragrances? In general, fragrances are volatile substances with a molecular weight of 100-300, with a carbon atomic number of 20 or less, hydrophobic but slightly soluble in water, and able to bind to olfactory receptors.

In fragrances, API (Active Pharmaceutical Ingredients) and Agrochemical (Agrochemical fragrances), there are very few molecules containing aromatic rings or molecules with many heteroatoms (if the molecule contains many heteroatoms then the molecule is odorless). Most fragrance molecules are made up of carbon, hydrogen and oxygen atoms, while some contain nitrogen or sulfur atoms. Although there are few optically active molecules among the lower molecular weight molecules, there are exceptions: menthol, and in some optically active molecules different optical isomers of the molecule make up the substance with different odors.

The odor we usually smell in our life is from a mixture of dozens or hundreds of compounds, so even if we find it very unpleasant, the GC-MS-O analysis shows that there are substances with aromas mixed in the mixture. Of course there are also substances with very bad odor in this mixture. For details, see the study of odor components emitted by giant flowering konjac [2]

Aromas emitted by the combination of different compounds

The most important thing for fragrance compounds is the combination of compounds. Fragrances are made by mixing several compounds in a certain ratio to obtain complex aromas that cannot be given off by individual compounds. The skill of combining different compounds comes from the cultivation process of the perfumer and the accumulation of process knowledge (know-how), so this technique is not as simple and easy as we think.