76 PRESERVATIVES


plant residues, such as fruit peels, husks, or fibrous crop waste, these materials are repurposed into effective, high-performance cosmetic ingredients. This approach lowers carbon emissions,


reduces landfill burden, and supports resource efficiency - key factors in meeting today’s environmental and regulatory expectations. For brands, upcycled ingredients offer more than just ecological benefits. They allow companies to tell compelling,


transparent product stories that resonate with eco-conscious consumers who increasingly seek out ethical, waste-reducing alternatives. As the industry continues to shift toward responsible sourcing and cleaner formulations, upcycled raw materials are positioned to play a central role in shaping the future of sustainable beauty: combining environmental value with proven cosmetic performance.


A question of responsibility: natural vs. synthetic origin While functionality is a prerequisite, the sustainability profile of raw materials is increasingly becoming a deciding factor for cosmetics manufacturers. Consumers no longer distinguish between performance and ethics, they expect both. This shift is reflected in the rise of certified natural cosmetics and the growing interest in circular economy principles. Natural pentylene glycol answers this call with


a truly future-oriented concept. It is produced through the upcycling of agricultural by-products - specifically, fibrous plant waste from sugar cane and corn cultivation. Instead of being discarded or burned, these residual materials are transformed into a high-purity, multifunctional ingredient via a green chemistry fermentation process. This not only reduces waste and carbon emissions but also minimises competition with food resources. The result is a pentylene glycol grade that is 100% of natural origin, fully compliant with COSMOS and NATRUE standards, and suitable for vegan and cruelty-free formulations. Alongside the natural grade, synthetic


pentylene glycol offers the same high-quality performance in a more economically efficient format. Synthetically derived, it is well-suited for large-scale production or formulations where natural certification is not a requirement. This grade also features a particularly mild


odour, making it suitable for applications where sensory neutrality is desired. Both versions share identical technical characteristics, giving formulators full flexibility to choose the most appropriate grade based on formulation goals and market positioning (Table 1).


Multifunctionality and emulsion stabilisation Pentylene glycol exhibits a broad spectrum of functionalities, making it a truly multifunctional component. Its ability to boost skin hydration is well documented. Due to its hygroscopic nature, pentylene glycol helps maintain moisture levels within the upper layers of the skin.1 This contributes to a supple, moisturised skin


feel and helps support a healthy barrier function, an essential aspect of modern skin care concepts. In addition, pentylene glycol serves as an effective solvent for a wide range of water-


PERSONAL CARE September 2025 No diol


4% Pentylene Glycol


dmean % change


12.0 µm -0%


soluble and oil-soluble cosmetic ingredients. It helps dissolve challenging raw materials such as botanical extracts and preservatives, enabling their even distribution within the formulation. This function ensures that performance


ingredients are bioavailable and optimally delivered to the skin.2,3


Its solvent properties


also contribute to the clarity of aqueous gels and the stability of emulsions by improving the homogeneity of the final product. Pentylene glycol can affect the viscosity of emulsions, especially when incorporated to the aqueous phase. This effect is mainly attributed to its hygroscopic and solvent-like nature, which can reduce water activity and weaken interactions within viscosity-building networks, such as polymeric thickeners. By partially disrupting the hydrogen bonding in the aqueous phase, pentylene glycol lowers the overall viscosity and modifies the rheological profile of the formulation. In systems relying on water-phase thickeners, the addition of pentylene glycol may require an adjustment of the viscosity. Additionally, its low molecular weight and amphiphilic character improve the mobility of the continuous phase, which can result in a thinner, more fluid emulsion consistency. This effect can be beneficial for achieving lighter textures or improving spreadability in serums, lotions, or sprays.


Diols, such as pentylene glycol, play a


supportive role in stabilising emulsions through their unique physicochemical properties. Due to their amphiphilic nature, diols can interact with both the aqueous and oil phases, helping to improve the uniformity and distribution of droplets within an emulsion system. This interaction can reduce droplet coalescence and


8.2 µm -31.7%


Figure 1: Particle size reduction for increased emulsion stability measured by static light scattering (ISO 13320-1) with Bettersizer S3 Plus in O/W emulsion consisting of 79.5% water phase and 20.5% oil phase


phase separation, leading to enhanced emulsion stability over time. Pentylene glycol’s ability to reduce droplet size in emulsions was proven by a static light scattering experiment: the average oil droplet diameter in an O/W emulsion containing 4% pentylene glycol was reduced by 31.7% compared to an emulsion without any diol (Figure 1). Their compatibility with a wide pH range and


various emulsifier systems makes diols versatile stabilisers, particularly valuable in minimalist or natural formulations where emulsifier concentrations are reduced.


Antimicrobial effect and mechanism of action Equally important is its role in preserving microbiological integrity. Pentylene glycol displays antimicrobial activity, which is independent of pH and effective even at low concentrations. This makes it an ideal component for clean and minimalistic formulations, especially where the goal is to reduce or even eliminate conventional preservatives. Its efficacy lies in its amphiphilic molecular


structure. Like other surface-active agents, pentylene glycol integrates into the lipid membranes of microorganisms. By disrupting the membrane’s structural integrity, it causes leakage of intracellular components and ultimately cell death.


This mechanism ensures a broad antimicrobial


effect without the need for harsh or controversial preservatives, making it suitable for sensitive skin. Its skin tolerability and non-irritativeness was proven by patch test. Pentylene glycol exhibits strong synergistic effects when combined with organic acids, other


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