Sometimes innovation begins with an everyday observation. As Andrea Johnson poured herself a glass of sparkling water in her kitchen, she paused for a moment to watch the bubbles. Some rose to the top immediately, while the smaller ones hung longer in the liquid. “I started considering how this observation might apply in my work,” she recalls today.
Andrea Johnson is responsible for Evonik Active Oxygens’ food safety business in the Americas region. She wondered: Could especially tiny gas bubbles have a role to play in industrial food safety? This question gave rise to an idea that is now being rolled out among Evonik’s customers in food processing.
A size comparison
Much smaller than a human hair
Electrically charged surfaces
The protagonists here are called nanobubbles. With a diameter of around 100 nanometers, they are roughly a thousand times smaller than a human hair and even significantly smaller than many bacteria. Unlike ordinary air bubbles, they do not simply rise to the water’s surface and burst. They are electrically charged, stay unusually stable, and can remain dispersed in liquids for days or even weeks. These properties make them highly interesting to researchers.
Their behavior is related to their size. Because nanobubbles are so small, they have an enormous surface area relative to their volume. At the same time, they exhibit a high “zeta potential”: an electrical surface charge that influences their stability and distribution in liquids. This allows them to interact intensively with particles, biological surfaces, and dissolved substances.
ELEMENTS-Newsletter
Get fascinating insights into Evonik’s research and its relevance to society, delivered straight to your inbox.
Food disinfection
Such properties make them especially useful in disinfection, for example. A team at Evonik investigated how these tiny gas bubbles can be combined with peracetic acid, an antimicrobial substance that has been used in the food industry for years. The goal was to improve the quality of disinfection and more effectively reduce microorganisms on product surfaces.
The challenge is significant. In poultry processing, the proliferation of pathogens such as Salmonella, Campylobacter, or E. coli must be reliably prevented in order to meet high standards for product quality and food safety. Producers need methods that are both effective and practical.
Peracetic acid has established itself as an important tool for this purpose. It is used at various stages of the processing chain and can be applied as a spray or rinse, or in cooling or immersion systems. Yet the chemical is not only powerful, it is also biodegradable: It breaks down after use into only water, oxygen, and acetic acid, a natural substance. This makes it an attractive choice for poultry producers who are concerned about chemical residues.
The intriguing question now was: Can nanobubbles further enhance the effectiveness of a proven process?
Enhanced performance of peracetic acid
Initial trials suggest so. The combination of peracetic acid and nanobubbles reduced more microorganisms on product surfaces than peracetic acid alone. The researchers believe that the tiny gas bubbles improve contact between the disinfectant solution and the surface. This could allow the active ingredient solution to distribute more evenly and reach areas that were previously harder to access.
Earlier studies have already shown that peracetic acid alone has a fundamentally high disinfecting effect, demonstrating significant reductions in Salmonella and Campylobacter. The new trials with nanobubbles aim to further exploit this potential.
Focus of scientific research
The nanobubble technology developed and patented by Evonik is already being rolled out in poultry processing plants. Yet getting from theory to practical application was not without its challenges. The Evonik team needed to scale up the technology in order to produce nanobubbles consistently in industrial quantities. The goal was to produce bubbles of uniform size using a system that could be integrated seamlessly into existing process plants. Only then did a laboratory phenomenon become an industrially viable technology.
For researchers, the topic’s fascination goes beyond this specific application. Nanobubbles show that a seemingly familiar phenomenon like a gas bubble can develop entirely new properties on the nanoscale. They remain stable, behave differently from ordinary bubbles, and influence the interaction between liquids and surfaces. This is precisely why they are increasingly becoming the focus of scientific research.
Real-world testing ground
Poultry processing serves as a real-world demonstration for a broader research question. Researchers are already discussing potential applications in water treatment, aquaculture, agriculture, industrial cleaning processes, and environmental technologies. Whether and to what extent this potential can be realized remains to be seen. However, the results so far indicate that a tiny gas bubble could conceal a multifaceted field of research.
Perhaps the most exciting insight, then, is not that nanobubbles are tiny, but that they raise a new question: What happens when a gas bubble becomes so small that it no longer follows the rules of everyday physics? The answer to this question could help make processes more efficient, safer, and more resource-efficient in the future.
