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The importance of UV disinfection

Cleaning not only the eggs but also the rollers

Moba egg graders are packed with technology. Some designs are worth further investigation as they represent crucial customer value. In this series of articles, we will be zooming in on these "hidden gems". UV disinfection is a feature found on many types of food handling and processing machines, including egg graders. But what is it and why is it important?


Over the rainbow

Ultraviolet light, 'UV' for short, is a small portion of the light spectrum. Everyone knows the phenomenon of a rainbow, where white sunlight is split up into a range of colors, from red to orange via yellow to green, blue and finally violet. But beyond these colors that can be seen by the human eye, the spectrum continues. A little further than red there is infrared light with a slightly longer wavelength. This infrared light is invisible to the human eye, but can be sensed in the form of heat.


Lethal weapon against horizontal transmission

At the other end of the spectrum beyond violet, there is light with a shorter wavelength, referred to as ultraviolet. This UV light is also invisible to the human eye, but everybody knows UV because it causes sunburn. And that is exactly the property that we are using in egg grading.


Your skin is hurt because UV light damages living cells by destroying DNA. However, too much sunburn is not healthy and will destroy too many skin-cells. The DNA in those skin cells is so damaged that the skin is no longer capable of reproducing healthy cells to repair the skin.


The advantage of this rather dangerous effect is that if harmful bacteria, viruses and molds are exposed to UV light, they are also destroyed and are unable to reproduce. And this is what we use for egg production. An egg can already be infected in the chicken. In this case, which is called vertical transmission, the egg is infected from the inside and if this happens, UV treatment does not help. Only microorganisms that are exposed directly to UV are killed. Since the UV only affects the surface and does not penetrate the egg, this type of vertical contamination is not cured by UV.


But most of the infected eggs are caused by horizontal transmission. In this case, an initially good and healthy egg rolls over contaminated surfaces and picks up harmful microorganisms that can penetrate the eggshell from the outside. Microorganisms can migrate into the egg more easily especially when the shell suffers some micro-cracks. And this type of horizontal transmission is very much limited by the use of UV.

The UV unit not only cleans eggs but also the rollers

All Moba graders can be equipped with UV disinfection. This system is a unit under which eggs rotate on rollers long enough to ensure that even the biggest egg will make at least one full rotation. Special lamps are mounted in this unit, emitting the most effective UV light. This UV-C light has a wavelength of 254nm and is used at an intensity that effectively reduces all forms of salmonella species. This UV-C exists in sunlight but is for the most part filtered by our atmosphere. Lamps however can generate this type of light very effectively. And because it is the most dangerous type of light, special tunnel constructions protect the entry and exit of the unit so that no harmful light can escape.


The UV-C light not only reaches the eggshells but also shines directly on the rotating rollers. And this is perhaps even more important, as it prevents the rollers from building up contamination that could potentially cross-contaminate other eggs.


Repeated tests show the positive effect

99.9% of eggshell surface contamination is erased. This is called a log 3 reduction and in itself provides a 1000x smaller risk. The results for heavily contaminated rollers are even better: after 7 passes under UV light the contamination is no longer measurable. The outcome of the first test in 2006 is available and has been scientifically published (if you are interested you can find this here). Later tests have shown similar results. The tests also ensure that the egg content is not affected at all.

UV light is not a magic trick that solves all hygienic problems, but it is a very valuable step in a hygienic program. UV light is a natural phenomenon and is present in everyday sunlight. Infected eggs are not perse cured by exposing them to UV but the chances for cross-contamination are reduced more than a thousand times. The chance that the rollers of the grader itself become a source of cross-contamination is almost zero. Because of this, it forms a barrier that is difficult to pass for serious contamination, when used in combination with other good hygienic practices, of course.

In Omnia PX more use of UV

All Moba machines can be equipped with a UV unit on the infeed roller conveyor. The Omnia PX series goes one step further than any other grader in the world. All egg touching surfaces have disinfecting properties and in some cases, this is also achieved by the use of UV light units. In other situations, where UV light is impossible to implement, industrial plastics with disinfecting properties called "Ovoshield" are used. This will be explained in the next issue of Moba News.


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