What is the HLB value?
If you stir emulsions and have already looked into emulsifiers, you might have stumbled upon this term before. But what does it mean and how can it help you?
HLB is the abbreviation for “hydrophilic-lipophilic-balance”. You could translate it as the balance between hydrophilicity (water-loving) and lipophilicity (oil-loving).
Most substances are either water-loving or oil-loving. This means they only dissolve in one phase. For example, sugar can be easily dissolved in water, but never in oil. Paraffin wax, on the other hand, can be easily dissolved in (hot) oil, but never in water. This means hydrophilic substances are also lipophobic (oil-repelling) and conversely, lipophilic substances are also hydrophobic (water-repelling).
Emulsifiers or surfactants have the special feature that they are both water-loving and oil-loving. They are therefore amphiphilic (water- AND oil-soluble). Because they dissolve in both phases, they can be used for emulsifying or cleaning.
Is an amphiphilic substance equally soluble in water and oil?
No, not necessarily. Every amphiphilic substance has a differently pronounced solubility. For example, it might prefer water and like oil only a little, or vice versa. The HLB value was created to categorize substances and their preferences.
Substances that are predominantly water-loving have a value above 10, while more oil-loving ones are below 10. You could also say:
- The lower the HLB value, the more the emulsifier likes (and needs) oil -
- the higher the HLB value, the more the emulsifier likes (and needs) water.
Depending on their value, they are used for different purposes. For instance, surfactants typically used for washing have a high HLB value and are therefore highly water-soluble, while a very low HLB value results in W/O emulsifiers.
Rich and light emulsions
Classic oil-in-water (O/W) emulsifiers usually have an HLB value of approx. 10. While all of these form O/W emulsions, the rule still applies here too – a lower value likes (and needs) more oil. This means the emulsifier is better suited for higher fat phases – and thus richer emulsions. If you want to create a light emulsion with a high water content, you should choose an emulsifier with a high HLB value.
Emulsifier mixtures (blends)
So much for the theory. In practice, however, mixtures of several substances with different HLB values are primarily used, as they all have their pros and cons. These “blends” usually work better and lead to more stable emulsions. In this case, you don't even have to pay that much attention to the HLB value, as a sophisticated mixture balances out minor weaknesses.
You might have noticed that we offer some ready-made emulsifier blends - now you know why.
If you want to learn more about this topic and how you can use the knowledge of the HLB value for your own purposes, then visit our Masterclass! Here, we will take a close look at the topic of emulsifiers and surfactants.