As a formulation expert, what are the biggest challenges you face when working with natural/ sustainable ingredients, and how do you address issues such as stability, efficacy, or sensorial properties while maintaining a commitment to sustainability?
We live in the age of growing transparency, as consumers and even regulators are requesting more information than ever before.  Therefore, before addressing stability, efficacy and sensoriality profiles of ingredients, it is essential to set a sustainability framework that is workable for the brand and that reflects the ethos behind it. This means reality checks and discussions, using as much data as possible and finding the ingredients partners that are on the same wavelength. 
This is because the plant origin of an ingredient is just the tip of the iceberg and all sorts of information are required. Starting with the supply chain of the raw material including biodiversity and ending with end of life data, such as biodegradability and aquatic toxicity. There is also a growing focus on social criteria such as fair wages and child labour. The recent scandal by the BBC investigation in Egyptian Jasmin cropping involving children was a big surprise especially because big corporations have been using such jasmin in high end perfumes (1).
If a quantitative approach like LCA is chosen then metrics regarding the production of the ingredient are also needed, but unfortunately they are not available as one would expect. However, I expect metrics to become more common in the next few years.

Overall, the ultimate solution to getting ingredients with good data comes down to working with quality suppliers that are prepared to invest in disclosing and optimising this other dimension of ingredients production. Products certifications such as Cosmos, Natrue, UEBT and even process certifications such as RSPO can help the selection process as several sustainability criteria are included in the standards already.
Because of this complexity there is a lot of work going into the decision making process well before the formulation development starts. And I must say, there is rarely a perfect solution, because even if you find the perfect ingredient for the formula, it might come from far away or the price might be higher than you would like, etc. However, the overall outcome is a positive improvement, so no black and white, but different shades of grey.

Once the sustainability criteria are set and you have a positive list of ingredients to use then it makes sense to work on the actual formula to achieve good stability, efficacy and sensoriality. Thanks to an incredible amount of innovation by the cosmetic industry there is a great selection of green chemistry ingredients with great sensorial profiles, from emulsifiers, to rheology modifiers, silicone alternatives, biodegradable surfactants, film formers, microplastic free alternatives for glitter. There are also refined vegetable oils that have much less odour and colour and can be stabilised with natural antioxidants. There is still work to do, obviously, but every time I moderate the sustainability zone theatre at In Cosmetics Global I am surprised and excited by the amount of innovation. An example is the launch by Lubrizol of an inherently biodegradable and microplastic free acrylate copolymer with a low Carbon footprint and natural content. I find this launch a promise for even better innovation to come in the near future.

Given the above I would say the biggest challenge is not finding the right ingredients to achieve stability, good sensoriality profile and efficacy, but having a realistic formula budget for innovative quality ingredients with a transparent supply chain and data. At a time of increased cost of living even if money is tight, according to Mintel (2) it is all about value, quality and convenience of use, something that formulations made with the green ingredients of today can deliver.

Formulating sustainably is certainly harder but despite that its comprehensive approach is gradually being integrated in the conventional formulation process more and more, driven by consumers trends and even regulatory mounting pressure. And above all it allows you to develop future proof formulations.

How is cosmetic preservation going to be affected by formulating more sustainably?
Cosmetic preservation is not excluded by this trend and in a way it had a head start well before other ingredients, thanks to the “free from” trend. This led to developing several natural derived multifunctional ingredients that have multiple functions, such as foam boosting with antibacterial properties, or antioxidants with bacteriostatic or antifungal properties. Several of these green materials have also been used in synergistic blends with Annex V preservatives allowing a lower level of use, making them really a good fit for the trend “making more with less”.
In the recent years there have been also interesting launches such as plant derived Sodium Benzoate that is Cosmos approved and even Phenoxyethanol with 25% Renewable Carbon Index. This really shows the effort and opportunities behind natural preservation today. Other ingredients used in hurdle technology, traditionally made from petrochemicals, such as Propylene glycol, Butylene glycol and Pentylene glycol have also been made available via green sources thanks to the advancements of biotechnology.

Despite the abundance of multifunctionals and green preservatives, it can be quite challenging for formulators to find them all in one place and choose the relevant ones. That is why I decided to write a book collecting a selection of raw materials I came across over the years, showing INCI, trade names, regulatory status, Cosmos status and other relevant data in one place, saving time and hassle. The book is a virtual one and can be purchased on my website.