Pulsed light processing
- How does it work?
- What can it be used for?
- What can it not be used for?
- Related Facilities
- Further Information
|Key words||pulsed light, UV, non-thermal technology, decontamination, inactivation, microorganisms, bacteria, moulds, yeasts, viruses, spores|
How does it work?
|Primary objective||Non-thermal microbial inactivation of food products, food related packaging and food processing equipments.|
|Working principle|| Pulsed light (PL) technology involves the use of intense and short duration light pulses. The spectrum of the light pulses is broad, ranging from ultraviolet (UV, 100 nm) to near infrared (nIR 1100 nm), with a considerable amount of light in the short-wave UV domain. To produce the light pulses, electromagnetic energy is accumulated in a capacitor during fractions of a second and then released in the form of light within a short time (ns to ms). The resulting effect consists in an amplification of power with a minimum of energy consumption.
Light pulses used for food processing applications typically emit 1 to 20 flashes per second at an energy density in the range of about 0.01 to 50 J/cm2 at the treated surface. Although the light spectrum generated by the PL technology has a similar composition to sunlight, the disinfection effects arise because the intensity involved is roughly 20,000 to 90,000 higher than that of sunlight at earth’s surface. In comparison with the continuous UV light disinfection systems, the PL technology shows considerable advantages:
The mechanism of action of the PL processing is very complex including short-term, thin-layer temperature effects – phototermic effects (the treated surfaces briefly reaching 300-7000C), photochemical effects (formation of free radicals) and DNA damage to micro-organisms [1, 2]
With PL processing theres is a reduction of the spoilage of treated products by inactivation of moulds, yeasts, fungi, viruses and bacteria (Salmonella, Typhimurium, Listeria, Pseudomonason, Campylobacter, E.coli, etc.)
|Additional effects|| The PL technology was reported [1-3] to show additional positive effects such as:
In some cases, heating of food products accompanying the PL process, can induce the negative effects specific to thermal processing. The most important technological problem related to the use of PL technology consists in finding ways to control (to avoid) food heating and to treat foods homogeneously.
|Important process parameters||light pulse intensity, pulse number and duration, light spectral composition, light source positioning, distance to the sample|
|Important product parameters||absorption/transmission of the treated product, surface topography, penetration depth, opacity, transparency of food product and package|
What can it be used for?
|Products||Liquid foods (cold pasteurization of liquid food such as milk, juices) and solid foods (fruits, vegetables, eggs, shell, fish and meat) to be disinfected|
|Operations||Disinfection and preservation of food products.|
|Solutions for short comings||
What can it NOT be used for?
|Products|| For opal products the PL technology is only a surface treating method. To keep the appropriate level of efficiency of the PL technology, a uniform treatment of the target surface is required.
Restricted products are:
|Operations|| The PL technology is a non-thermal technology. However, heating may occur accidentally during the use of PL technology. In order to avoid this effect, the following recommendations are desirable:
|Other limitations||Uniformity of the treatment is limited by the product geometry and opacity.|
|Risks or hazards||PL technology is considered free of any health risks. However, more research is needed on the nutritional consequences and on the applicability of photosensitization to foods. PL is safe to apply but some precautions have to be taken to avoid exposure of workers to light and to evacuate the ozone generated by the shorter UV wavelengths More research is needed on the nutritional consequences of applicability of photosensitization to foods and possible formation of toxic by-products.|
|Maturity|| This technology is available at industrial scale. Laboratory studies demonstrated that PL disinfection technology is clearly efficient, but its efficacy on real foods is still under investigation.
Further studies are necessary in order to:
|Modularity /Implementation||PL processing can be incorporated easily into in-line manufacturing processes. Due to its flexible design and scalability, PL could become a relatively inexpensive solution for small- or medium-size companies.|
|Consumer aspects||PL processing corresponds to the increased consumer awareness about minimally processed foods [7, 9].|
|Legal aspects|| PL treatment was approved for food surface decontamination by the US Food and Drug Administration (FDA) in 1996. The approved procedure uses light pulses of wavelengths between 200-1000 nm, with a pulse width not exceeding 2 ms and the cumulative level of the treatment not exceeding 12 J/cm2 (FDA Code 21CFR179.41).
The legal status of PL technology in the European Union has a different approach, since the legislation is not technology oriented but food and food ingredient oriented. The PL technology fall in the scope of Regulation (EC) 258/97 on novel foods and novel food ingredients, article 1, item f (European Union, 1997). Among other categories, this legislation applies to foods and food ingredients to which a production process not currently used has been applied, and evaluates possible changes in nutritional value, metabolism and level of undesirable substances.
|Environmental aspects||PL processing is an energy-saving, waste-free, environmentally friendly technology.|
Facilities that might be interesting for you
light pulse intensity, pulse number and duration, light spectral composition, light source positioning, distance to the sample absorption/transmission of the treated product, surface topography, penetration depth, opacity, transparency of food product and package Light equipment 2.1.1 physical stabilizing other Science Direct, Scopus Search terms: pulsed light, decontamination WikiSysop :Template:Review document :Template:Review status