Sucrose esters – the multifunctional, cold-processable emulsifier

With Sisterna SP70-C, an HLB 15 sucrose stearate in powder form, formulators can design a cold process o/w emulsion. This article from Sisterna zooms in on the possibilities of this production method and explains the crucial additional benefits of sucrose esters. These advantages combined with a cold processing method result in excellent formulations that meet the sustainability and clean beauty needs of consumers.

The most common way to make an o/w emulsion is using a hot production method. The pros of this type of production technique is that the heating energy eases the emulsification step. Another argument is that the heat could kill all the microorganisms. Of course, you have your solid ingredients which require heating. But if you can work around using solid ingredients, there are many benefits to making a cold process emulsion. It’s a much easier process as it’s safer to prepare and more economical than heated emulsions. The reduced energy consumption makes a cold manufacturing process more environmentally friendly and it doesn’t present any limitations in terms of the temperature sensitivity of ingredients.

Cold emulsification possibilities

Sisterna SP70-C is an HLB 15 powder-grade emulsifier, which makes it quite unusual for use in a cold process. However, it’s easily cold-dispersible in the oil phase.

A basic formulation with Sisterna SP70-C is presented in Table 1 with comparisons between an oil phase of 20% up to 60% and the effects on the oil droplet size and viscosity.

Two common oils are also compared:

1. sunflower oil, which is a more polar vegetable oil

2. isopropyl myristate (IPM), which is a medium polarity ester oil.

Oil concentration and droplet size

High shear is enough to produce standard emulsions with Sisterna SP70-C. There are no particles visible and it gives droplet sizes between 1µm and 10µm, small enough to obtain a stable emulsion while having an oil phase of 20% to 60%.

With a 60% oil dosage, 3% of Sisterna SP70-C works well. At lower oil levels of 20% to 30%, it’s possible to reduce the dosage to 2%.

Oil concentration and viscosity

In order to select the right viscosity of the formulation, it’s important to note that the higher the oil phase (internal phase), the more viscous the product becomes. There is a slight difference between the two oils used, as IPM gives a slightly higher viscosity (see Figure 1).

Another key consideration is that it’s not only the oil concentration that can influence the viscosity, but also the selected hydrocolloid, which can have a big impact. Using a viscosity-increasing hydrocolloid, such as sclerotium gum, gives a good viscosity build-up as well as stability to the emulsion.

The benefits of sucrose esters

Although we’ve already mentioned the reason why cold emulsification is so interesting, there are more objectives why it should be done specifically with sucrose esters. The ability to combine the benefits of Sisterna SP70-C with this manufacturing technique gives the formulator an opportunity to design products in line with the current natural, clean beauty and responsible cosmetics trends. The result is an innovative processing technique that is ideal for creating simple and effective natural formulations.

Sisterna SP70-C is a non-ionic and PEG-free/ethylene-oxide-free emulsifier, which is very mild on skin (see Figure 2). It is suitable for use in cosmetics designed for sensitive skin, or for children and babies. It even has irritation-reducing capabilities when dosed with other (anionic) surfactants/emulsifiers that are usually more irritating, making the total formulation milder on skin.

The most well-known benefit of sucrose esters is the skin feel. It gives a very soft touch when applied on skin and has a velvet-like after-feel. This skin feel is largely independent of the oil phase. Even when you dose a very greasy oil, the greasiness will be eliminated by the use of sucrose esters.

Certified natural and food-grade

Skin moisturisation is one of the most important aspects of personal care products. Figure 3 shows that sucrose esters increase the moisture level of the skin, making them more than just an emulsifier. It shows the comparison in skin hydration of a basic emulsion made with only Steareth-2 and Steareth-21 (placebo formula), and the same emulsion to which 2.5% of Sisterna SP70-C is added.

Sucrose esters are also food-grade ingredients, they don’t have any taste or odour and do not cause any colour deformation in production. Being edible is usually important for formulators as it indicates a product is very safe to use. Sucrose esters are also certified by some of the most respected certification bodies in Europe and the United States, including Ecocert, COSMOS and the NPA. In addition to its naturality, Sisterna SP70-C is readily biodegradable.

Less is more in clean beauty

It is well-known that consumers are increasingly focused on the naturality of a formulation, in addition to their interest in a product’s biodegradability and the way in which it’s produced or manufactured.

Consumers are more aware of ingredients and know that a long INCI list on a product’s packaging no longer means the product is better. This is the ethos of clean beauty, where less is more, conveyed in a simple INCI list that consists of safe and effective ingredients.

Because of the multifunctional benefits of sucrose esters, like the mildness, skin moisturisation and skin feel, combined with cold processability, naturalness and being readily biodegradable, formulators can design very effective and responsible formulations with a short INCI list. You do not need any extra ingredients to make a formulation milder, improve moisturisation or adjust the skin feel.

A co-emulsifier is not needed as it can be used as a single emulsifier. The only things that are needed, along with water and sucrose esters, are an oil of your choice, a stabilising system, preservative and an active ingredient. A formulation such as this is featured in Table 2.

This Lagom lotion Sweden formulation goes back to the basics, not only keeping it simple and effective but also considering the environment and maintaining that less is definitely more.

Contact Danlink Ingredients, the exclusive South African distributor for Sisterna, for more information, technical notes and guide formulations on sucrose esters.

Did you know?

Sisterna SP70-C shows selective antimicrobial properties. It actively targets microorganisms that cause nappy rash, athletes’ foot and odour formation, making the emulsifier an ideal active ingredient for use in products designed to address these concerns. Furthermore, Sisterna SP70-C does not interfere with the skin flora.