Deactivation of organisms using high-intensity pulsed...

Details Deactivation of organisms using high-intensity pulsed... Deactivation of organisms using high-intensity pulsed...

1998-02-18

2001-05-08

Gorgos, Kathryn (Department: 1741)

Chemical apparatus and process disinfecting, deodorizing, preser

Chemical reactor

With means applying electromagnetic wave energy or...

C422S022000, C422S023000, C422S024000, C210S748080

Reexamination Certificate

active

06228332

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to disinfection or decontamination of food, water, air and packaging materials, and more particularly, is directed to deactivation or killing of organisms, such as cyst-forming protozoa, such as
Cryptosporidium parvum,
or viruses, such as poliovirus, in food, water, or air, or on packaging material. Even more particularly, the present invention relates to deactivation of such organisms using high-intensity short-duration pulses of polychromatic light in a broad spectrum.
As used herein the terms “deactivate”, or decontaminate and forms thereof refer to the killing or sterilizing, i.e., rendering unable to produce, of microorganisms.
Substantial technical effort has been directed to increasing the levels of microbiological decontamination in water, air, foodstuffs and other microbiologically labile products, and packaging materials so as to preserve these products against microbiological spoilage and/or to prevent infection of their consumers. Such efforts have involved both the treatment of products and packaging material, and the development of packaging techniques for preservation.
The photobiological effects of light, including infrared light (780 nm to 2600 nm; i.e., 3.9×10
14
Hz to 1.2×10
14
Hz), visible light (380 to 780 nm; i.e., 7.9×10
14
Hz to 3.9×10
14
Hz), near ultraviolet light (300 to 380 nm; i.e., 1.0×10
15
Hz to 7.9×10
14
Hz) and far ultraviolet light (170 to 300 nm; i.e., 1.8×10
15
Hz to 1.0×10
15
Hz), have been studied, and, in particular, efforts have been made to employ light to deactivate microorganisms on food products, containers for food products or medical devices. See, e.g., U.S. Pat. Nos. 4,871,559;
4,910,942; and 5,034,235, issued to Dunn et al. (the '559, '942, and '235 patents), incorporated herein by reference.
Other studies of the photobiological effects of light are reported in Jagger, J., “Introduction to Research in Ultraviolet Photobiology”, Prentice Hall, Inc., 1967. U.S. Pat. No. 2,072,417 describes illuminating substances, e.g., milk, with active rays, such as ultraviolet rays; U.S. Pat. No. 3,817,703 describes sterilization of light-transmissive material using pulsed laser light; and U.S. Pat. No. 3,941,670 describes a method of sterilizing materials, including foodstuffs, by exposing the materials to laser illumination to inactivate microorganisms. However, such methods have various deficiencies, such as limited throughput capacity, limited effectiveness in killing microorganisms (particularly, cyst-forming protozoa and viruses), adverse food effects (e.g., negatively affecting food flavor or appearance), inefficient energy conversion (electrical to light) and economic disadvantages.
In the area of water decontamination in particular, heretofore known methods of killing cyst-forming protozoa are in many cases ineffective and inefficient, i.e., overly time consuming or too costly. One commonly used method of water decontamination is the addition of chlorine to water for the purpose of killing microorganisms. Unfortunately, chlorine, at levels that are not also toxic to humans, is ineffective at killing some cyst-forming protozoans. In recent years, for example, outbreaks of
Cryptosporidium parvum
(
C.parvum
) have caused illness in hundreds of thousands of people, and have killed numerous others. Such outbreaks are common in the spring and summer rainy seasons when water from feedlots and the like may be undesirably mixed with municipal water supplies. No cost effective method of eradicating
C.parvum
has heretofore been available.
One attempt to eliminate live
C.parvum
from water involves exposing contaminated water to ultraviolet light. While limited success has been observed using ultraviolet light and special methods for increasing exposure time or intensity (such as by trapping oocysts in a mechanical filter and exposing the mechanical filter to ultraviolet light) to eradicate low concentrations of
C.parvum,
i.e., about 2 log cycle reductions, such method requires that the water be exposed to ultraviolet light having an intensity of 15 W/s for more than two hours, i.e., about 150 minutes. Thus, the use of ultraviolet light has proven not to be a viable approach to eradicating
C.parvum
in municipal water treatment facilities. What is needed is a method of eradicating
C.parvum,
other cyst-forming protozoa, and other microorganisms, such as viruses, that is both fast, i.e., that can be used practically in a water treatment facility, and that is highly effective, i.e., is effective to deactivate high levels of
C.parvum,
i.e., more than 2 or 3 log cycles.
In the area of air decontamination, airborne microorganisms, and in particular viruses, and even chemical contaminants, are of major concern. In order to be effective, an air treatment approach must be able to process flowing air as it passes from a contaminated space into an uncontaminated or sterile space. Heretofore, the most common method of air treatment has been to employ micro filters, such as HEPA filters, in a duct in order to physically remove particulate contaminants from the flowing air. Unfortunately, the micro filters employed pose significant impediment to air flow, and therefore require the use of high powered fans and the like in order to pump the air through the air filters. As more particulate contaminants become trapped in the micro filters over time, this impediment to air flow increases. In addition, due to the relatively high resistance to air flow posed by such microfilters, leakage of air around the filters becomes a significant factor in their design. Such filters also are subject to releasing trapped contaminants into the duct when they are removed for replacement and such released contaminants can be subsequently carried by the duct into areas sought to be protected by the filter. Furthermore, some microfilters may be unable to remove particularly small contaminant particles.
SUMMARY OF THE INVENTION
The present invention advantageously addresses the needs above as well as other needs by providing a method for deactivating cyst-forming protozoa, such as Cryptosporidium parvum, and viruses, such as poliovirus, using short duration pulses of very intense polychromatic light. Application of short duration pulses of high intensity, incoherent polychromatic light provides efficient, effective, high throughput processing and results in many practical and economic advantages.
Generally, in accordance with the present invention, methods are provided for deactivating microorganisms, including cyst-forming protozoa and viruses, by exposing the microorganisms to at least one short duration pulse of incoherent polychromatic light having an energy density in the range of from about 0.01 to about 50 joules per square centimeter using a wavelength distribution such that at least about 50%, and preferably at least about 70% or even 95% of its electromagnetic energy is distributed in a wavelength range of from 170 nanometers to 2600 nanometers, and a duration in the range of from about 1×10
−6
to about 1×10
−1
seconds, but preferably less than about 10 milliseconds.
Desirably, at least about 40 percent, and typically greater than about 70 percent of the energy of the light pulses should be of continuous emission spectra. However, intense pulses from sources including significant line emission spectra may also be beneficially utilized in specific processes. Such short, intense, incoherent light pulses may be provided by pulsed, gas-filled flashlamps, spark-gap discharge apparatuses, or other pulsed incoherent light sources.
Pulsed, gas-filled flashlamps produce broadband light when an electrical current pulse is discharged through the flashlamp, ionizing the gas and producing an intense burst of both continuum and line emission over a broad spectral range. Such flashlamps typically employ inert gases such as Xenon or Krypton because of their high efficiencies of electrical to optical energy conversion. The use

Affiliated with

Also associated with

Rating

Deactivation of organisms using high-intensity pulsed... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Deactivation of organisms using high-intensity pulsed..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deactivation of organisms using high-intensity pulsed... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2501374