Making scents last – researchers find new way to encapsulate fragrance molecules

One of the biggest challenges for manufacturers when it comes to fragrances is that they are amphiphilic and easily evaporate at normal temperatures meaning it is difficult to encapsulate them efficiently.

There are some traditional approaches to do this but it has proved difficult to effectively retain the fragrance in microcapsules.

Publishing their work in the journal ACS Applied Materials & Interfaces​​, ​the researchers aimed to address this by incorporating a stable fragrance-in-water (F/W) emulsion that is primarily prepared from bulk emulsification, within a polymer microcapsule via microfluidic emulsification.

On the basis of the in-depth study of physicochemical properties of the microcapsules on fragrance leakage, David A. Weitz and his colleagues demonstrated that enhanced retention of fragrance can be achieved by using a polar polymeric shell and forming a hydrogel network within the microcapsule.

“We further extend the utility of these microcapsules by demonstrating the enhanced retention of encapsulated fragrance in powder state,”​ he notes.

Encapsulating challenges​

The challenge with creating long-lasting fragrances is that aroma molecules tend to be small and volatile, which means they can sneak through barriers easily and disperse quickly.

As mentioned, some methods have been developed to prevent fragrance molecules from hastily escaping from a spritz of perfume or a dollop of lotion, such as in one process which slows down the molecules by packaging them in microcapsules.

However this technique can be inefficient and doesn't control for shell size, thickness or structure, which makes it harder to work with.

Weitz and the research team wanted to figure out a new strategy using microfluidic and bulk emulsification to encapsulate fragrances and set about doing so with funding from Procter & Gamble, the National Science Foundation, the Harvard Materials Research Science and Engineering Center, and the National Research Foundation of Korea.

To begin with, in order to get a homogeneous mixture of water and α-pinene molecules,found in oils from pine trees and rosemary, the researchers emulsified them.

Pumping the emulsion into tiny glass microfluidic tubes created uniform microcapsules. Testing showed that the capsules successfully slowed the release of α-pinene.

In addition to its use in the fragrance industry, the researchers say the technique could have applications in drug delivery or other areas.