Perfume compositions are an important part of many industries ranging from the luxury goods sectors, food services industries, to manufacturers of various household chemicals. The purpose of using perfume or fragrance compositions in these industries is to affect customers through their sense of smell and entice them into purchasing the perfume or perfumed product. As such there is significant interest in producing a perfume formulation that people will find aesthetically pleasing.
The job of composing perfumes that will be sold is left up to an expert on perfume composition or known in the fragrance industry as the perfumer. They are also sometimes referred to affectionately as a “Nez” (French for nose) due to their fine sense of smell and skill in smell composition.
The composition of a perfume typically begins with a brief by the perfumer’s employer or an outside customer. The customers to the perfumer or their employers, are typically fashion houses or large corporations of various industries. The perfumer will then go through the process of blending multiple perfume mixtures and sell the formulation to the customer, often with modifications of the composition of the perfume. The perfume composition will then be either used to enhance another product as a functional fragrance (shampoos, make-up, detergents, car interiors, etc.), or marketed and sold directly to the public as a fine fragrance.
Although there is no single “correct” technique for the formulation of a perfume, there are general guidelines as to how a perfume can be constructed from a concept. Although many ingredients do not contribute to the smell of a perfume, many perfumes include colorants and anti-oxidants to improve the marketability and shelf life of the perfume, respectively.
Perfume oils usually contain tens to hundreds of ingredients and these are typically organized in a perfume for the specific role they will play. These ingredients can be roughly grouped into four groups:
- Primary scents (Heart): Can consist of one or a few main ingredients for a certain concept, such as “rose”. Alternatively, multiple ingredients can be used together to create an “abstract” primary scent that does not bear a resemblance to a natural ingredient. For instance, jasmine and rose scents are commonly blends for abstract floral fragrances. Cola flavourant is a good example of an abstract primary scent.
- Modifiers: These ingredients alter the primary scent to give the perfume a certain desired character: for instance, fruit esters may be included in a floral primary to create a fruity floral; calone and citrus scents can be added to create a “fresher” floral. The cherry scent in cherry cola can be considered a modifier.
- Blenders: A large group of ingredients that smooth out the transitions of a perfume between different “layers” or bases. These themselves can be used as a major component of the primary scent. Common blending ingredients include linalool and hydroxycitronellal.
- Fixatives: Used to support the primary scent by bolstering it. Many resins, wood scents, and amber bases are used as fixatives.
The top, middle, and base notes of a fragrance may have separate primary scents and supporting ingredients. The perfume’s fragrance oils are then blended with ethyl alcohol and water, aged in tanks for several weeks and filtered through processing equipment to, respectively, allow the perfume ingredients in the mixture to stabilize and to remove any sediment and particles before the solution can be filled into the perfume bottles.
Instead of building a perfume from “ground up”, many modern perfumes and colognes are made using fragrance bases or simply bases. Each base is essentially modular perfume that is blended from essential oils and aromatic chemicals, and formulated with a simple concept such as “fresh cut grass” or “juicy sour apple”. Many of Guerlain‘s Aqua Allegoria line, with their simple fragrance concepts, are good examples of what perfume fragrance bases are like.
The effort used in developing bases by fragrance companies or individual perfumers may equal that of a marketed perfume, since they are useful in that they are reusable. On top of its reusability, the benefit in using bases for construction are quite numerous:
- Ingredients with “difficult” or “overpowering” scents that are tailored into a blended base may be more easily incorporated into a work of perfume
- A base may be better scent approximations of a certain thing than the extract of the thing itself. For example, a base made to embody the scent for “fresh dewy rose” might be a better approximation for the scent concept of a rose after rain than plain rose oil. Flowers whose scents cannot be extracted, such as gardenia or hyacinth, are composed as bases from data derived from headspace technology.
- A perfumer can quickly rough out a concept from a brief by combining multiple bases, then present it feedback. Smoothing out the “edges” of the perfume can be done after a positive response.
Creating perfumes through reverse engineering with analytical techniques such as Gas chromatography–mass spectrometry (GC/MS) can reveal the “general” formula for any particular perfume. The difficulty of GC/MS analysis arises due to the complexity of a perfume’s ingredients. This is particularly due to the presence of natural essential oils and other ingredients consisting of complex chemical mixtures. However, “anyone armed with good GC/MS equipment and experienced in using this equipment can today, within days, find out a great deal about the formulation of any perfume… customers and competitors can analyze most perfumes more or less precisely.”
Antique or badly preserved perfumes undergoing this analysis can also be difficult due to the numerous degradation by-products and impurities that may have resulted from breakdown of the odorous compounds. Ingredients and compounds can usually be ruled out or identified using gas chromatograph (GC) smellers, which allow individual chemical components to be identified both through their physical properties and their scent. Reverse engineering of best-selling perfumes in the market is a very common practice in the fragrance industry due to the relative simplicity of operating GC equipment, the pressure to produce marketable fragrances, and the highly lucrative nature of the perfume market.