UV LEDs key to more hygienic beer brewing: Fraunhofer R&D project

UV light inactivates germs in drinking water. Until now, this disinfection process has typically relied on mercury-vapor lamps, which
emit light in the UV spectrum. However, mercury is a toxic heavy metal
that can damage both human health and the environment.Water Purification Equipment
Now researchers at the Fraunhofer Institute for Optronics, System Technologies and Image Exploitation (IOSB) in Ilmenau, Germany, are
investigating a greener and more efficient alternative, which uses UV
LEDs to destroy bacterial DNA. The technology is also suitable for
disinfecting brewing water and for disinfecting the caps for bottled
beer, soft drinks, and mineral water during the filling process.

To ensure clean water for high-quality beer, brewing companies often install ultraviolet systems upstream of their brewing equipment, to
keep the drinking water free of germs. UV light is used because it is
effective in killing bacteria, viruses and germs; their genetic material
is destroyed by UV.

The brewing water is disinfected by pumping it through stainless steel tubes in which UV lamps have been fitted. UV light with a
wavelength of 265nm is especially suitable for this task. Up to now,
this UV light has been generated using mercury vapor lamps, which emit
light at 254nm.

Researchers at the Advanced System Technology AST branch of the IOSB in collaboration with project partner Purion, are working to replace
conventional lamps containing mercury with ultraviolet light-emitting
diodes. Based in the German town of Zella-Mehlis, the company
manufactures UV disinfection systems for purifying water. The technology
is used in water coolers, for example, but also to keep drinks
containers such as barrels, bottles and cans free of germs.

“Conventional mercury-vapor lamps emit light at 254 nanometers. As this lies below the optimal wavelength of 265 nm, the disinfection
performance is not optimal,” said Thomas Westerhoff, a scientist at
IOSB-AST. Further disadvantages of these lamps are their long warm-up
phases, their short service lives and the fact that they cannot be
deployed flexibly due to their bulky design.

“For these reasons, we prefer UV LEDs, which emit at a maximum wavelength of 265 nanometers. Of particular interest are UV-C LEDs,
because their radiation destroys the DNA of the pathogens much more
effectively.

“The UV rays generate resonances in the nucleic acids of the DNA and break the bonds of the molecules open. This changes the cell nuclei of
the micro-organisms in a way that renders cell division impossible.
Consequently, the pathogens can no longer multiply.