Around the world in 80 particles – A sweet tooth…

With stay at home advisories and social distancing, our fast-paced lives have been brought abruptly to a halt… as if we’ve been suddenly made to stop and reconsider. All around the world, we went back to the basics: a deep breath in, a home-cooked meal, the warm smell of cookies in the oven. We are all baking in earnest. Flour, yeast, and sugar have been flying off store shelves. A major hotel chain just released their secret chocolate chip cookie recipe¹.

And here is our own baker Henry, my colleague’s little one, making a cake with his mom. While keeping him busy and entertained, she taught him about measuring, weighing and, if you look closely, about particle sizes in sugar. Indeed, a fine sugar is better for the buttercream, while a granulated one improves the cake’s texture.

Sugar and particle sizes are two of my favorite things. I am no sugar expert – although I love sugar in all shapes and forms: powdered, granules, cubes and even brown and unrefined sugars that seem to be so fashionable lately. I did learn a bit about particle sizing while working for Malvern Panalytical for the last 13 years. In fact, I even measured particle size distributions of sugars.

As a commodity, it’s not surprising how much science goes into making and testing sugar. Among the various international commissions that regulate and standardize analysis methods for food metrology, the International Commission for Uniform Methods of Sugar Analysis² publishes detailed laboratory procedures for sugar testing. In fact, its current method book contains 112 methods for sugar and sugar-related products analysis. The methods serve to assess sugar quality, grades, color, polarization properties, particle size distributions and many more such attributes.

Although sieving is the current method of choice for particle size distributions analysis in sugars, laser diffraction can also be used as a quick and robust method for sugars within a wide range of sizes. Dry laser diffraction is best for testing sugar granules in their actual dry form without fear of dissolution or the use of expensive solvents. Wet laser diffraction can also be used during the crystallization process. Once the particle size distributions are measured, typically reported sugar grade parameters such as mean aperture and coefficient of variation can be quickly calculated using various moment means³:

• The mean aperture MA = D[50]
• The coefficient of variation CV(%) = (D[84]-D[16]) / (2*MA)*100

Size distributions and associated sugar grade parameters measured with laser diffraction for two sugar samples on the Mastersizer 3000⁴ system equipped with the Aero S dry accessory are shown below. Analysis can be performed in less than 1 minute, with excellent reproducibility.

Now, let me go learn something about that flour…

References

1. https://newsroom.hilton.com/static-doubletree-reveals-cookie-recipe.htm
2. International Commission for Sugar Analysis
3. Halden, H. “A simplification of the method for obtaining mean aperture and coefficient of variation of granulated sugars”. Journal of the American Society of Sugar Beet Technologists 14, No. 4 (1967): 267
4. Malvern Panalytical – Mastersizer Range