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Emulsipedia entry: Emulsifier usage in spray drying

Emulsifiers are used in various products to make them shelf stable from food to cosmetics, but how do you make those products and what process is usually involved? Spray drying is one possible unit operation where emulsifiers are constantly being used.

Spray drying is taking a liquid slurry and then converting it to a powder via water removal through a heated process. To make an effective slurry that will dry, emulsifiers are often used. The choice of emulsifier depends on multiple factors including end application and regulatory implications. HLB values are key for the type of emulsion that is to be made, with oil in water emulsion requiring typically HLB values in the 12-16 range (those that are soluble in water) while 4-6 HLB values for water in oil emulsions (those that are soluble in oil) are typically used. Knowing these values is critical in choosing the right hydrophilic-lipophilic conditions for the emulsion. Many a times, one emulsifier may not be enough so a combination of emulsifiers must be chosen since HLB values are additive (for example, if you need an HLB of 9, you can take 50% of an ingredient that is HLB 10 and 50% HLB 8 to make HLB 9) such that the emulsion that is formed is stable. If spray drying, it is important to remember that the emulsion stability is dependent on all ingredients.

 

Prior to spray drying, a slurry is formed which usually includes a carrier (starch or gum of some sort), an active component (the material you want to turn into a powder), and an emulsifier. Once all the ingredients are combined, the slurry is fed through a two-stage homogenizer at a certain pressure to make the emulsion. If a two-stage homogenizer is not available or needed, a high shear homogenizer is often used. The former allows for a finer emulsion micelle versus the latter. If the emulsion is stable after homogenizing, the slurry is then pumped into a heated chamber where water removal occurs resulting in a fine powder end product. This powder can then be used in various food, beverage, cosmetic, etc. applications.

With the push into having a product that is clean label, ingredients like polysorbate 60 and soy lecithin are being looked at to be replaced with ingredients like quillaja extract and sunflower lecithin. Gums like gum arabic are used often as carriers in the spray drying process not only because the active is encapsulated effectively but also because gums are clean label ingredients that also act as an emulsifier. Hydration time is key when working with gums for them to properly ‘bloom’ to allow for mixing with the active.  

The healthy halo is being looked at by both consumers and manufacturers but what is forgotten is that if choosing a replacement, the new replacement should be able to function in the emulsion as well as be able to produce the same quality powder. Looking for ingredients that are environmental friendly and sustainable is important but the end application must not be degraded by this switch.

About the author

Amit Sinha

Amit has been working in the food and beverage industry for the last 10+ years. Currently, he is working at Watson Inc. as a Process Innovation Engineer. Amit has a Master of Science in Chemical Engineering from University of South Carolina along with an MBA in Marketing from Regis University. He has an innate curiosity to learn about new foods and ingredients as well as enjoys participating in Crossfit and other fitness related events.