In-line sterilisation with pulsed light

The effectiveness of pulsed light in killing micro-organisms is well know, but until now there was no suitable testing environment that was sustainable and met industry standards. Claranor has developed a pulsed light sterilisation treatment that is reproducible and traceable. Each product receives exactly the same amount of energy, and the procedure is monitored and can be checked at any time

The Claranor equipment has been placed above the capper, in the capping and filling closed area

Chemicals may be the conventional means of disinfection when it comes to food packaging but Claranor illustrates that for some applications pulsed light technology has additional benefits.

Pulsed light technology has existed in a lab environment for almost 40 years. Microbiologists have known of the effects of pulsed light on micro-organisms, but in the past there was no suitable testing environment that was sustainable and met industry standards. Today there is.

Based in Avignon, south of France, Claranor has been a provider of disinfection technologies since 2004, and in that short time has gathered the necessary skills to bring pulsed light technology to a range of applications. In particular it has developed systems for the sterilisation of caps, cups and packaging. It has also completed validation and qualification trials with independent laboratories, including the Fraunhofer Institute in Germany.

The company has completed many projects for industrial food, beverage and dairy product manufacturers and it also collaborates with equipment suppliers looking to integrate the technology into complete production lines, retrofit or new.

Such technology, supplied by the company, is already being used by international beverage and dairy production groups, such as Nestlé Waters and Lactalis.

The pulsed light sterilisation treatment is completely reproducible and traceable. Each product receives exactly the same amount of energy, and the procedure is monitored and can be checked at any time

The pulsed light sterilisation treatment is completely reproducible and traceable. Each product receives exactly the same amount of energy, and the procedure is monitored and can be checked at any time. On top of these benefits, working with pulsed light is much more environmentally friendly. The energy consumption for running the pulsed light unit is not significant compared with the whole line consumption, and it uses neither water nor chemicals and thus has no chemical residue.

Beverage line solution

These benefits were of interest when Aujan Industries was facing a microbiological issue with its flavoured beverage containing a high level of sugar.

Aujan Industries is located in Dammam, Saudi Arabia and produces beverages for the Middle East and African market. Its three factories in Dammam, Dubai and Iran produce flavoured beverages, carbonated soft drinks as well as malt beverages, that together generate an annual turnover of about US$1bn.

The product in this instance, which can be stored at ambient temperature for several months, was packaged using a special packaging method: hot filling at 80–85°C.

Prior to 2011, the bottles were turned upside down once filled and capped, to decontaminate the cap with the heated liquid and thus secure the package. But this step was lengthening the production process considerably and the company wanted to improve production line efficiency.

Pulsed light was chosen as the new disinfection technology rather than chemical methods because of its compactness, low operational cost and process simplification.

Pulsed light was chosen as the new disinfection technology rather than chemical methods because of its compactness, low operational cost and process simplification

The pulsed light equipment was integrated on an existing Sidel line, producing 42,000 bottles/hr. One flash per cap (a Corvaglia and a Portola cap with a 28mm dia.) was enough to achieve the level of decontamination required. The Claranor equipment has been placed above the capper, in the capping and filling closed area.

Installed in 2011, Aujan Industries is satisfied with the equipment: “After six months of production, Claranor equipment has demonstrated what we were expecting: full bacteriological treatment of our caps, no recorded contamination on product, ease of operation and maintenance, very positive support from Claranor… [and] low operational cost,” says the engineering and project manager of Aujan Industries.

Pulsed light disinfection: how it works

The basic principle of pulsed light sterilisation is to destroy micro-organisms using short, intense light flashes generated by xenon lamps.

The energy needed for product decontamination is accumulated in a capacitor. A high-voltage signal initiates the so-called “arc formation”. The arc comprises highly ionised gas with strong currents.

Xenon gas is used because of its capacity to convert electrical energy into light energy. This arc starts the flash of intense luminosity.

The peak power of one flash is around 1 megawatt (Mwatt). The flashes present a continuous spectrum, rich in UV light, that lasts a few hundred microseconds. The housing of the lamp is made of quartz, so almost no optical energy is wasted. The flashes are controlled and concentrated by aluminum reflectors, specifically designed for each application.

Each flash produces an enormous amount of energy. With a lamp energy of 300J and a flash time of 0.3mS, that is 1Mwatt (or 1kW per cm2 of the treated object).

The micro-organisms absorb all the energy – mainly that in the far UV domain.

Pulsed light has a destructive effect on micro-organisms thanks to a combination of two effects:

The sterilising effect of UV: the DNA in the cells of micro-organisms absorb the UV rays. This ruptures the double strands of DNA and provokes the formation of abnormal single-strand bonds. This prevents DNA replication. The micro-organism’s protein production and cell metabolism is blocked and it dies.

The power of the flash: the intense energy delivered in a very short time increases this lethal effect.

A Claranor installation consists of two parts:

1. The electronics bay: powered by the main current this generates the electrical pulses. The integrated cooling system regulates the temperature of the water in the lamp circuit.

2. The optical cavity: This is where the light is generated, powered by the electronic bay. It has flash lamps and a reflector that focuses the light towards the surface that needs to be treated.

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