conditioners and potato tumblers are being engineered to deliver a dose of
short-wave ultraviolet light to control mold, viruses and bacteria that infect
S. Scheir, president and chairman, Steril-Aire Inc., Burbank, CA
From radio signals to gamma waves, the electromagnetic
spectrum offers considerable potential to prepare and preserve food products.
Knowing precisely which wavelength in the spectrum to apply to a particular
need is only the first step, however: scientists and engineers also need to
fabricate systems that can withstand the rigors of an industrial environment.
The application of UVC, short-wave ultraviolet in the C band range (200 to 280
nanometers) to inactivate mold, bacteria, fungus, viruses and other spoilage
organisms illustrates the development challenge.
UV lamps to treat germicidal disease date to the 19th
Century, when Nobel laureate Niels Ryberg Finsen used UV to treat skin
infections in treatments that presaged today’s chemotherapy. After the 1976
Legionnaire’s Disease outbreak in a Philadelphia
hotel, medical science linked Legionella bacteria to heating, ventilating and
air conditioning (HVAC) systems that can spread bacteria and viruses thriving
in warm, moist environments. Among the scientists who worked on a solution was
Brad C. Hollander, who developed a UVC lamp to improve indoor air quality.
Hollander was issued a patent in 1994 for an electric discharge device to
sterilize HVAC air, and the following year Steril-Aire Inc. was established to
commercialize the technology. The company now is based in Burbank,
CA, and is headed by Robert S. Scheir,
president and chairman.
In one of the 10 US patents assigned to Steril-Aire, Scheir
cites a study involving a 20-year-old HVAC system in City of Industry, CA.
Biocides, high-pressure sprayers and other treatments provided temporary
removal of mold and bacteria from the cooling coils, but buildup resumed in as
few as three days. The inventor configured germicidal lamps to permanently
resolve microbial encrustation on the coils and boost heat transfer efficiency
up to 30 percent, improving airflow and energy efficiency by a similar amount.
holds a PhD in medical microbiology from UCLA and performed graduate studies in
immunochemistry at the School
of Hygiene and Public Health at Johns Hopkins University. Before joining Steril-Aire,
he was a senior scientist at McDonald-Douglas Corp., specializing in
biological-warfare detection instrumentation.
array of short-wave UV lamps provides a kill step against mold, viruses and
bacteria in this tumbling drum bound for duty in a potato processing plant.
Source: Steril-Aire Inc.
FE: How do your lamps differ from a bug zapper?
Scheir: Bug lights mounted on a wall emit UV waves that are
close to 400 nanometers. The light attracts flying insects, which fly to the
light source and are electrocuted.
UVC from vaporized mercury lamps emit waves of 253.7
nanometers, which is close to 265, the wavelength that destroys DNA and
provides maximum germicidal effectiveness. Altering the DNA prevents
replication and causes cell death. Effectiveness of UVC is directly related to
time and intensity. The intensity 2 inches from the lamp is almost three times
greater than at 6 inches, and at 12 inches intensity is half the level at 6
inches. Total irradiation also is impacted by reflectance within the cavity.
With aluminum and aluminized materials, you get about 85 percent bounce off the
surface, potentially increasing the dosage received by organisms.
FE: What does your firm manufacture?
Scheir: We have developed system-engineered UVC emitters
that, unlike conventional UVC lamps, work in cold environments. Standard UVC
lamps lose output to the point they don’t work below 40