Editorial Feature

What to Know About Particle Sizing of Flavor Emulsions

Particle size analysis of flavor emulsions is extremely crucial in the food and beverages industry to monitor the flavor, texture, and stability of the emulsions. This article discusses the importance of particle size analysis of flavor emulsions and the methods used to perform the analysis.

Particle Sizing, particle analysis, flavour emulsions, flavor emulsions, flavor particles

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Importance of Particle Size Analysis

Flavor emulsions are water and oil emulsions typically prepared as a concentrate and can be diluted during the formation of a final product. Two flavor emulsion types are primarily used in the food industry, including a flavor emulsion with a high concentration oil emulsion, which is essential oil stabilized using additives using stabilizers and emulsifiers, and a flavored oil emulsion with added vegetable oil formulated to provide a cloudy appearance.

Flavor emulsions are stabilized by adding hydrocolloids, such as carrageenans, alginates, gum Arabic, and xanthan gum. These hydrocolloids can provide both steric/electrosteric and electrostatic stability to the emulsion.

Particle size analysis of flavor emulsions is performed to monitor their stability in both diluted and concentrated forms over time by tracking changes in the distribution and size of the droplets. Specifically, the creaming of oil and sedimentation of flocculated material to the top of the container and at the bottom of the container, respectively, must be prevented.

The optimal particle size of flavor emulsions is less than three microns. Particle size analysis methods, such as laser diffraction, can be utilized to monitor changes in particle size upon dilution/storage, identify and reject unstable formulations, and ensure optimum sizing of the droplets.

Sugar crystallization in flavor emulsions can also lead to batch-to-batch problems and affect the stability of the system. Particle size analysis can be performed to identify large particles such as coalesced sugar crystals/oil droplets.

Particle Size Analysis Methods

Dynamic Light Scattering (DLS)

DLS/quasi-elastic light scattering/photon correlation spectroscopy is a non-destructive/noninvasive technique for measuring particle size from the submicron to the micrometer region. Macromolecules and particles in a solution undergo Brownian motion caused by the collisions between the solvent molecules and particles.

The light scattered from the particle ensemble due to Brownian motion fluctuates with time. A digital correlator in DLS adds and multiplies these short-time scale fluctuations continually in the measured scattering intensity for autocorrelation function generation. This function is analyzed to obtain the diffusion coefficients and, then, the particle size information.

In most DLS instruments, a coherent monochromatic helium-neon laser with a fixed 633 nm wavelength is utilized as the light source. The light source converges to a waist of focus in the sample using a focusing lens. Although light is scattered at all angles by the particles in the flavor emulsion, a DLS instrument typically detects the light scattered at 90o.

DLS is a versatile and fast particle size analysis technique that can be used to determine the particle size distribution of the emulsion to monitor the emulsion’s stability. For instance, the particle size analysis of a flavored alcoholic beverage emulsion can be performed by initially diluting the sample using a sodium chloride solution and then using a Zetasizer Nano system with four mW helium-neon laser operating at 633 nm wavelength at 25 oC for analyzing the diluted sample.

In a study published in the journal Bioactive Carbohydrates and Dietary Fibre, researchers used DLS for successful particle size distribution measurement of food-grade flavor emulsions of cardamom and vanilla prepared using galactan exopolysaccharide (EPS). The Galactan flavored emulsions (GFE) were diluted using distilled water before the particle size analysis.

Although conventional DLS instrumentation requires the sample to be diluted significantly to reduce multiple scattering effects and allow free movement of particles, such dilution of samples can also change their morphology, which is a major challenge of using this technique. 

Laser Diffraction

Laser diffraction is used extensively for particle size analysis in the food and beverages industry, including for the particle size analysis of flavor emulsions. In this method, particles passing through a laser beam scatter light at an angle that is related directly to their size. The observed scattering angle logarithmically increases with the decreasing particle size.

The scattering intensity is also dependent on the particle size as it diminishes with particle volume. Thus, large particles scatter light with high intensity at narrow angles, while small particles scatter light with low intensity at wider angles. This phenomenon is exploited to determine the particle size.

A laser diffraction system consists of a laser/an intense, coherent light of fixed wavelength, a series of detectors, and a type of sample presentation system. The particle size distributions in laser diffraction are determined by comparing the scattering pattern of the sample with a proper optical model.

The method is suitable for particle size analysis of flavor emulsions as it is non-destructive, reliable, fast, and versatile, has high repeatability and flexibility, does not require calibration, can generate volume-based particle size distributions, and can detect both agglomerated and well-dispersed particles effectively.

Specifically, the extensive dynamic range of this method from 0.02 microns to a few millimeters allows the characterization of both larger coalesced/flocculated droplets and fine emulsion droplets in flavor emulsions to monitor emulsion stability.

In a study published in the journal Food Science and Biotechnology, researchers used a laser-diffraction particle size analyzer to successfully determine the particle-size distribution and mean particle sizes of the double-emulsified mayonnaise samples.

Image Analysis

Image analysis is suitable for analyzing both particle shape and size as it generates data by capturing direct images of every particle with high resolution and sensitivity. The images of individual particles enable the detection of crucial phenomena, such as breakage, foreign particles, and agglomeration.

In volume-based techniques, larger particles are more heavily weighted compared to smaller ones. However, the additional resolution provided by the image analysis technique ensures that every particle is weighted equally, leading to more effective identification of smaller particles.

To summarize, DLS, laser diffraction, and image analysis currently play an important role in particle size analysis of flavor emulsions. However, particle size analysis can be improved using more advanced instrumentation and developing novel and more effective methods.

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References and Further Reading

Kavitake, D., Kalahasti, K. K., Devi, P. B., Ravi, R., Shetty, P. H. (2020). Galactan exopolysaccharide-based flavour emulsions and their application in improving the texture and sensorial properties of muffin. Bioactive Carbohydrates and Dietary Fibre, 24, 100248. https://doi.org/10.1016/j.bcdf.2020.100248

Bancarz, D., Huck-Jones, D., Kaszuba, M., Pugh, D., Ward-Smith, S. (2008). Particle Sizing in the Food and Beverage Industry. Nondestructive Testing of Food Quality, 165–196. https://doi.org/10.1002/9780470388310.ch7

Yildirim, M., Sumnu, G. Sahin, S. (2016). Rheology, particle-size distribution, and stability of low-fat mayonnaise produced via double emulsions. Food Science and Biotechnology, 25, 1613–1618. https://doi.org/10.1007/s10068-016-0248-7

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Samudrapom Dam

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Samudrapom Dam

Samudrapom Dam is a freelance scientific and business writer based in Kolkata, India. He has been writing articles related to business and scientific topics for more than one and a half years. He has extensive experience in writing about advanced technologies, information technology, machinery, metals and metal products, clean technologies, finance and banking, automotive, household products, and the aerospace industry. He is passionate about the latest developments in advanced technologies, the ways these developments can be implemented in a real-world situation, and how these developments can positively impact common people.


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