The Basics of Aroma principles

Fragrances and essential oils can add features and benefits to your cosmetic formulas, and be manipulated to suit a specific target market. These may include one or more of the following:

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• tangible benefits: benefits that can be experienced. These can include consumer satisfaction, covering body odours, and leaving a lasting aroma.
• intangible benefits: benefits that can’t be measured but are still important. These can include evoking emotions, providing impressions of the product, or to suit certain desires.
• features: such as covering base smells of a formula, adding to product appeal, or working to support the branding of a range.

When formulating your product and selecting the appropriate aroma, remember to consider the needs and desires of the target market, and the purchaser of the product.

Starting materials of fragrances

Fragrances can be composed of between 20 to 100 or more aroma chemicals. These chemicals can be obtained from:

natural sources: 

1. components (isolates) from essential oils can be separated out and modified.
2. common examples include: eugenol from clove oil; limonene and citronellol from citrus oils.
3. the ever increasing number of natural fragrances now available are created from combinations of essential oil isolates in place of synthetic materials.  

synthetic sources:

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1. crude oil sources can provide hydrocarbon backbones which are then modified to produce a variety of fragrance compounds.
2. these are still the most common source of many fragrance starting materials. 

Finished fragrances can be combinations of natural and synthetic sources or created using all natural isolates or all synthetic isolates, depending on the needs of the brief and price requirements. 

Starting materials of essential oils

Essential oils are natural substances that are already blends. They don’t exist as just one compound like an aroma chemical does, which makes blending of essential oils more challenging, generally less substantive and some aromas not possible from natural sources. 

Essential oils are obtained through processing methods such as:

expression 

• used to extract essential oils from citrus fruits.
• in expression, whole fruits are fed into a rotating drum containing rows of spikes. As the fruit tumbles over the spikes, the peel is removed and the oil cells within the peel are punctured to release the oil. The collected liquid is then washed and separated by centrifuge to separate the oil from the aqueous portion.

extraction can be one of two types:

• maceration involves immersing the flower of a plant into highly purified fat for a period of time and then straining the fat to remove the plant debris. This process is repeated using fresh flowers and the same fat over and over, resulting in a highly fragrant fat known as a pomade. This pomade may then be mixed with ethanol, gently heated to remove the alcohol and fatty alcohols of the fat, until only a viscous, fragrant oil mixture remains.
• carbon dioxide (CO2) extraction can also be used to extract essential oils from plants. It involves extremely high pressures of carbon dioxide to extract the oil from the plant, and on removal of the plant debris and removal of pressure, the carbon dioxide is spontaneously released leaving only a very concentrated essential oil.  

distillation:

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• steam distillation is often used for essential oils, to protect their volatile components that would otherwise be destroyed or removed by prolonged contact with heat. In steam distillation, steam is used to heat the starting materials to release a vapour that is then collected, cooled and condensed into a distillate.

Hydrosols are the ‘by-products’ of essential oil steam distillation. They are the water component that is collected during steam distillation production of essential oils, and therefore carry the aroma of the essential oil created, but in a water soluble form. The aroma of hydrosols is very similar, but far less concentrated as the corresponding essential oil. Hydrosols do, however, remain very stable in a product formulation – they are heat tolerant having been creating through a steam distillation process – so don’t oxidise, and retain their aroma over time.  

Can Cosmetic Chemists also 
create fragrances?

Perfumers put a fragrance together much like a Cosmetic Chemist puts a formula together; using known materials, in various combinations, and then repeating samples and variants until they get the aroma just right to suit the client’s brief. To be a perfumer, you need to undertake extensive studies in perfumery and focus on that solely; in addition, to be a perfumer you need to have ‘the nose’; an incredibly acute sense of smell. This is not something that can be learnt – you either have ‘the nose’ and ability to be a perfumer, or not. 

You would typically be one or the other; not both. Cosmetic Chemists will order fragrances to suit a brief, but not actually be creating the fragrance blend; while Perfumers will create the fragrance, but not the finished product. Just as much effort goes into the creation of a fragrance, as would go into a cosmetic formulation. Therefore, not only would sourcing of raw materials be a huge issue if you were to attempt to formulate both, but the time taken to do both, by the one person, would be inefficient to product development. 

Fragrance houses are the best to provide fragrances because they contain multiple ingredients which must be purchased in at least 1-5kg quantities. This makes it cost prohibitive for a small manufacturer to purchase the individual materials for their own fragrance creation, as the cost to purchase and hold such large quantities of multiple chemicals, when only a small portion of these would get used in standard fragrance developments. 

Can you mix essential oils and 
fragrances?

While fragrances are a complex blend of 20 – 100 different aroma chemicals, added in very specific amounts by a perfumer, essential oils come from plants as blends already. 

As a formulator, you should never add essential oils to fragrances without knowing the chemical composition of the fragrance. The addition of an essential oil, which naturally contains a variety of different fragrance compounds, can reduce the stability and substantivity of the fragrance. It could also cause the final ‘blend’ to form undesirable odours over time. 

Adding isolates from natural essential oils is possible if you know the composition of the fragrance; or mixing essential oils with fragrances is possible if you are prepared to run extensive stability tests to monitor the aroma profile over time and be careful to detect unsuitable changes. 

Does a perfumer need to disclose the components of their fragrance?

No, a perfumer does not need to disclose the full list of components in their fragrance. They must provide you with an MSDS, ensure the contents of the fragrance comply with regulatory limits, and provide you with details of any allergens the fragrance contains, along with %w/w of those allergens. Beyond that, they do not need to disclose their fragrance formula. 

When requesting fragrance from a fragrance house it is a good idea to request their IFRA (International Fragrance Association) Certificate – the IFRA endeavors to make sure that the usage standards for fragrance materials are put into practice according to the available scientific recommendations and that member companies comply with those standards. This helps ensure consistency, quality and safety of fragrances and fragrance materials. To learn more, visit: ifraorg.org

A final note on this introductory 
lesson…

This is just the very tip of the iceberg when it comes to the science of perfumery and selection of essential oils. The power and romance of aroma in a cosmetic formula cannot be denied, so to add that extra dimension to your cosmetic formulations, make sure you submit a detailed brief to your fragrance house or learn how to blend essential oils for lasting, head-turning appeal to your finished products.