Flavor of the day: How to spray dry flavors and fragrances part 2!

How many of you have had the that smell of vanilla and cookies bring you back to your childhood and baking in the kitchen? You’re in luck, instead of launching a baking spree, my sense of smell reminded me I owe you a second post on how to spray dry flavors and fragrances. Hungry for it? Then read on!

A few days ago, I had the “fun task” to clean out our bathroom drawers. On one shelf, I found a box full of old perfumes, some of them, I dare say more than 25 years old. I took one cap off a perfume bottle and took a good whiff of the liquid inside. Immediately, I was flooded by memories of my younger days. So, I sat there and enjoyed the time, thinking back to all the special occasions for which I wore that perfume.

Do you know what else the powerful sense of smell reminded me of? I owe you a part two to our blog post on how to spray dray fragrances and flavors.

Don’t let that thought linger in the air longer than the scent of perfume in a crowded room. Let’s get right into it. I believe I promised you a discussion into spray drying parameters most suitable for spray drying of flavors and fragrances. Here they are:

  • Inlet temperature – Set your inlet temperature to a value where the temperature gradient between the wet droplet surface and hot saturated gas leads to the evaporation of the solvent. The more energy is put into the system, the faster the water is evaporated, which increases the drying efficiency. Quick drying also leads to rapid formation of a semi-permeable membrane on the droplet surface that retains the core material in the microcapsule. But, the droplet could inflate or breakdown when the boiling point of the liquids is exceeded.
  • Outlet temperature – You cannot set this temperature, it is a parameter governed by inlet temperature, feed rate, dryin gas, sample concentration and atomization gas performance.
  • Feed pump rate – The peristaltic pump feeds the emulsion to the nozzle. If you keep parameters constant, an increased feed rate usually results in bigger particle sizes, better separations and higher yields.
  • Drying gas and atomization gas – It has been observed that if you increase drying air flow rate, you will also increase encapsulation efficiency. This effect could be attributed to a lower relative humidity in the whole system. A small emulsion particle size is preferred when encapsulating flavors and fragrances, because it can lead to better mixing of atomization gas and emulsion. Smaller particle sizes retain volatiles flavors and fragrances due to more rapid heat and mass transfer (i.e. the drying process is faster).

Now how about some practical examples of how you can encapsulate different flavors and fragrances? Take a look at this table:

Flavor and fragranceCarrier materialFindings and benefits
Sulfur aromaArabic, maltodextrin or their mixtureObtained good retention; high yield; storage stability improved
Caraway essential oilWPC, SMP, and their mixtures with maltodextrinProved WPC per se and in combination with carbohydrates can be successfully used as wall materials; WPC exhibited better encapsulating properties than SMP
Limonene oilGum arabic, WPC, and their mixtures with cassava starchCreated microcapsule morphologies with uniform surfaces and without cracking, offered adequate protection to limonene oil
Coconut oil (containing vitamin A)Arabic gumExhibited spherical form and rough particle substances. Particle size in the range of 3.5 and 10.4 um; protect and stabilize vitamin A in the capsules
Chia seeds oilWPC/pectin + maltodextrin
WPC + HiCap 100
Compared different carriers for microencapsulation; the final microcapsules increased the induction time and enhanced stability
Pomegranate seed oilSMPOptimum operating conditions to achieve high encapsulation efficiency of 95.6%
Canola oilLentil protein isolate and maltodextrinEncapsulate canola oil in most effective encapsulation wall material with protection against degrading oxidative reactions
Walnut and chia oilHPMC; maltodextrinProtective effect to walnut oil and to chia oil with microencapsulation process
PhytosterolsArabic gum and maltodextrinPhytosterol microparticles with good characteristics were formulated and developed by spray drying
Sunflower oilHPMC; maltodextrinBased on RSM method to develop optimized encapsulation process

Lastly, I’d like to discuss some important characteristics of your fragrances of flavor-containing microcapsules.

Moisture content and water activity

Moisture is known to influence oil oxidation, flavor retention and the microstructure of particles. Moisture content of walnut or chia oil has been shown to be as low as 0.95%, whereas sunflower oil powder could have moisture levels as high as 4.86%. Water activity is usually associated with moisture content. Water activity influences the release of flavor and fragrances, as it could change the coating matrix structure. Low water activity slows the release of volatiles and inhibits microbial spoilage. High water activity could cause the matrix to plasticize, which increases the release rates of mobile flavors and fragrances.

Particle size, distribution and microstructure

These parameters could affect flavor, color, texture and odor of the product, as well as its flowability and dispersibility. Usually, when you encapsulate flavors and fragrances, you prefer uniform, homogenous and round particle morphologies. Research has shown that using an ultrasonic nozzle produces the narrowest size distribution compared to other nozzle types. I also want to add that microcapsules with a smooth surface, few concavities and wrinkles have beneficial effects on encapsulation efficiency and stability.


You can calculate the yield by dividing the weight of microcapsules solid mass by the total solid mass to be spray dried. The yield is influenced by many factors, such as the core and wall material, the ratio of core and shell material, the surfactant, inlet temperature, feed concentration and others. To increase yield, you could try to decrease the feed solids concentration and increase the core to wall material ratio. Increasing the inlet air temperature should also increase your yield.

Total oil content, surface oil and encapsulation efficiency

The total oil content of your microcapsules includes the surface oil and encapsulated oil. The presence of oil on the powder surface is an unwanted property with negative effects on storage stability. You can calculate the encapsulation efficiency by subtracting the surface oil content from the total oil retained after spray drying or by hydrodstillation of essential oil from the matrix after washing out the surface oil by organic solvent. Of course, when the highest encapsulation efficiency is achieved, you have the lowest oil content on the surface of the microcapsule, so your encapsulated flavors or fragrances are best protected from the surrounding environment.

Storage stability

And this brings us to the last point. During the storage period, microcapsules containing flavor and fragrances could be oxidized, resulting in odor deterioration. Storability is one of the main factors to determining encapsulation efficiency. Literature has shown, that for example, with chia oil, even after a 90-day storage period, the peroxide value (PV) of microencapsulated oil is considerably lower than nonencapsulated oil.

Whew, I hope I now gave you a good taste of how to spray dry fragrances and flavors. And if you want a quick refresher on the spray drying and microencapsulation techniques as a whole, check out a free spray drying guide or watch a brand new webinar on the topic of advanced spray drying. I do hope you found this post as flavorful as I did. What spray drying topic should we tackle next? Leave me a comment and I’ll see what I can cook up!

Till next time,

The Signature of Bart Denoulet at Bart's Blog