Looking at the back or bottom of the perfume box, we can see the alcohol content of the perfume. Common alcohol accounts for between 72% and 81%, and the most common ratio is 80%. So the question is, the alcohol content in perfume is so high, much higher than the proportion of essential oils, but why the taste of alcohol is not obvious?

The discovery of alcohol


In human history, when and how alcohol appeared, there is still no conclusion. There is only a related hypothesis as to why humans have the ability to metabolize alcohol. It is said that human ancestors primates often ate overripe fruits and competed with natural selection to leave genes. The earliest alcoholic beverage found by archaeology was found in a prehistoric tomb near Haifa, Israel. It belonged to the Neolithic period more than 10,000 years ago and was fermented from wheat and barley. Pottery pieces dating back about 7000 BC were unearthed at the Jiahu site in Henan, China. Residue analysis revealed traces of ancient wine made from grapes, hawthorn, honey and rice. According to the Guinness Book of World Records, the earliest evidence of winemaking dates back to Georgia around 6000 BC. However, there is still a long way to go from alcoholic beverages to the use of alcohol to make perfumes. The discovery, purification and use of alcohol components have been experienced in the middle.

First, the pungent smell of alcohol that many people remember is not the smell of alcohol itself, but the smell of impurities in alcohol. Industrial alcohol is produced by the hydration reaction of ethylene, which is derived from petroleum. This kind of alcohol contains methanol and cannot be eaten or used for medical purposes or used to make perfume. Alcohol that most people come into contact with is usually made by fermenting corn and sugar cane. It contains impurities such as acetaldehyde and fusel oil. These impurities have a pungent odor. One of them is specifically made into denatured alcohol to warn people not to drink it, and at the same time avoid the taxes imposed on alcoholic beverages in many countries. In the early days, denatured alcohol would add dangerous methanol, but now it’s not so frantic. It would add bittering agents, emetics, unpleasant pyridine or kerosene, and sometimes dyes to show distinction. The alcohol in high-end perfume is fermented with grapes. From the beginning, the impurities are much less. After the didealdehyde treatment, it is finally made into denatured alcohol without unpleasant substances and coloring agents. The smell of impurities is almost negligible. The most extravagant way is to age the alcohol itself with balsam, iris, animal scent, etc. The smell of pure alcohol is very weak, and I can even think of it as a rose.

Second, after the perfume is sprayed, the alcohol will generally evaporate quickly, leaving only a variety of spices. This is not like what some people say on the Internet. It is because the saturated vapor pressure of alcohol is the largest (Raoult’s law), because perfume is not an ideal solution. There are various interactions between various molecules such as dipoles, hydrogen bonds, and London forces. The role is to follow Henry's law, and at the same time, the sprayed perfume will also have molecular interactions with the surface of the medium. In this case, it is more reasonable to use the octanol-water partition coefficient to consider the adsorption of the medium, use the Hildebrand solubility parameter to measure component volatilization, and use the linear free energy relationship to predict the equilibrium state. The vapor pressure is indeed the main factor, as is the Kovac index. Friends who have the ability to learn can search for these terms to further expand. If it is simple, just remember the principle of similar compatibility.

Third, from the perfume being sprayed from the nozzle or applied to the skin, to the person's olfactory perception, volatilization is one aspect, while diffusion (Fick's law) and reception (Stevens power law) are the other. According to the previously published research results, if you use the principles of fluid mechanics and psychophysics to construct partial differential equations for the perfume system, find the numerical solution and visualize it, you will find that even if you only use limonene, geraniol, and gallo musk three A variety of fragrances, regardless of ideal or non-ideal conditions, most perfume ratios can achieve full coverage of the smell of alcohol. In other words, if you want to highlight the smell of alcohol in a perfume, it actually requires an exquisite formula and superb skills, which is quite rare.