Home Coffee product The problem with triboelectricity: lessons from coffee blends

The problem with triboelectricity: lessons from coffee blends


AsianScientist (7 March 2022) – The next time you make yourself a cup of 3-in-1 instant coffee, first shake the sachet vigorously. After pouring your shaken coffee powder, you may notice that the tiny particles have started to clump together, forming lumps in your cup or inside the packet itself.

Like the way a plastic comb can make your hair stand up, the agitated powder particles can clump together due to a physically induced static electrical charge, otherwise known as triboelectricity, and it affects more than coffee in your cup.

During manufacturing, the same phenomenon can cause powdered ingredients to stick together, leading to product buildup and possibly clogging of machinery. This problem, called fouling, causes disruptions and delays that cost the food and bioproducts industries in the United States about US$7 billion annually.

To better understand why fouling happens and how to prevent it, researchers at the Singapore Institute of Technology (SIT) studied the formulations of every household’s favorite 3-in-1 instant coffee powder. By investigating the cause of fouling as well as the electrostatic charge of each component, researchers found the ideal mix to avoid potential fouling issues when scaling or processing.

Associate Professor Wong Shin Yee (right) of SIT leads the triboelectricity-induced fouling minimization research project, together with research engineer Ernest Lim Teng Shuen (left).

Understanding fouling

“Food products tend to be formulated first for taste and nutrition before being scaled for manufacturing, so manufacturing issues such as fouling don’t surface until late in the process. product development cycle,” explained lead researcher Associate Professor Wong Shin Yee of SIT’s Food, Chemical and Biotechnology cluster. .

As a result, Wong and his team wanted to investigate whether powder fouling could be mitigated before manufacturing, taking these considerations into account even at the formulation stage. To do this, the team first visited industrial sites where they were able to observe the 3-in-1 instant coffee production process and determine the cause of the clogging.

“We observed that the ‘fouled’ powder could be easily brushed or patted onto the treatment surfaces, indicating the absence of physical adhesion or chemical bonding,” Wong said.

This observation strongly suggests that the powder adhesion that led to fouling was due to electrostatic attraction rather than chemical factors such as powder solidification or crystal formation, or biological factors. such as microbial growth and biofilm formation.

The team also noticed fouling occurring during the packaging stage. When powder is conveyed through narrow lanes to be dispensed into individual pouches, the physical contact and friction generate an electrostatic charge and lead to clogging.

The perfect formula

With the cause of the fouling firmly established, the next step for Wong and his colleagues was to devise a way to reduce the chances of it happening in the first place.

When researchers measured the electrostatic charge of different commercial 3-in-1 coffee blends, they found that blends with high negative charges tended to clog more easily, with the ideal charge being neutral or zero.

Realizing that altering the components and proportions of a powdered blend can also alter its electrostatic charge, Wong and his team analyzed each individual ingredient in the coffee blend to determine which formulation could bring the 3-in-1 coffee to that ideal state. .

They found that sugar with higher mineral levels generated less electrostatic charge when stirred and would therefore be less likely to clog. Meanwhile, coffee powders with lower caffeine levels and lower fat creamers generated less load.

From there, the researchers came up with the ideal formulation of the coffee blend to reduce the load and therefore reduce the risk of clogging.

“We recommend using high-mineral sugar, low-caffeine powdered coffee, and low-fat creamers,” Wong explained.

triboelectricity, powder fouling, sit
Wong and his team found that reformulating powder mixtures to neutralize static charge can minimize the risk of powders sticking to stainless steel.

Efficiency from the start

Despite establishing the correlation between powder formulation and electrostatic charge as well as the best formula to minimize clogging in the 3-in-1 instant coffee, Wong acknowledged that taste is still the main concern when it comes to coffee. involves formulating food products.

Even so, she sees her study as “building layers of protection” right from the product formulation stage.

“Although we initially started from a pain point during manufacturing, we discovered that there was a unique way to approach the problem by mitigating the problem more easily during formulation,” he said. she explains. “When it gets to production, then manufacturers can further ease the load through other innovative means.”

Beyond changing the product formula, Wong’s research also highlights the potential benefits of overhauling the product development process.

“If you look at a typical development cycle for new food products, there are usually two different groups of experts who lead formulation and process development separately,” Wong said. “From our study, it’s clear that this should be a combined effort: formulating with processing constraints.”

Wong’s research, which illustrates the development of a cycle of holistic solutions to potentially solve a persistent industrial manufacturing problem, exemplifies SIT’s goal of using applied research to develop and translate solutions that are beneficial to the industry.

“We are constantly reaching out to industry partners to surface interesting problems that can present themselves as opportunities for multiple layers of innovation and learning adventures,” Wong explained, adding that his findings throw the basics of a food technology knowledge base.

In line with Singapore’s 2020 Research, Innovation and Enterprise Strategy for Advanced Manufacturing and Engineering, Wong’s work paves the way for increased productivity in powder manufacturing, with the potential to grow further and help solve other problems in handling food powders.

“As an academic, I like to approach industrial problems as scientific adventures. All scientific adventures begin with validating ideas to determine if the adventure is worth exploring,” Wong concluded. “I am very grateful to everyone who worked on my blue sky projects and their persistence in obtaining scientific validations.”

Asian Scientist Magazine is a media partner of the Singapore Institute of Technology.


Copyright: Asian science magazine; Photo: Singapore Institute of Technology.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.