RESEARCH NOTE: USE OF PULSED ULTRAVIOLET LASER LIGHT FOR THE COLD
PASTEURIZATION OF BOVINE MILK
September, 2002
Journal of Food Protection: Vol. 65, No. 9, pp. 14801482.
WAYNE L. SMITH,a MANUEL C. LAGUNAS-SOLAR,b and JAMES S. CULLORa
aDairy Food Safety Laboratory, School of Veterinary Medicine, Veterinary
Medicine and Teaching Research Center,
University of California, Davis, California 95616, USA
bCrocker Nuclear Laboratory, University of California, Davis, California
95616, USA
http://www.foodprotection.org/QuickLinks.htm
ABSTRACT
Because of concerns that some potentially dangerous microorganisms may
survive conventional heat pasteurization of milk and because the heat needed
to sterilize milk affects marketability, the ability to efficiently cold
pasteurize milk may become more desirable. In this pilot study, we
investigated the use of pulsed ultraviolet (PUV) laser light to nonthermally
(cold) pasteurize bovine milk.
Dairy bulk tank milk was treated with UV light (248 nm) emitted from a
pulsed excimer laser. The samples were then analyzed for surviving bacteria
by spiral plate counting and subculturing in Trypticase soy broth. Other
bulk tank milk samples were inoculated with one of eight relevant milk
bacterial species before being exposed to laser light. There was no growth
observed for any of the plated or subcultured samples exposed to 25 J/cm2.
One bacterial isolate was then used to inoculate milk to further investigate
bactericidal laser light doses. Growth was observed for samples treated with
an average of 0.3 to 6.6 J/cm2 but not for those treated with 12.6 J/cm2.
The results indicate that in principle, the bacterial content of milk can be
adequately controlled by exposure to PUV laser light.
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Value of the bio-availability and content of calcium in milk needs to be appreciated. I never had a broken bone as a kid, although my leg was once bent sideways like a bow in a car accident. Bro and I each drank anything up to 4 liters of milk a day. In fact the only broken bone I ever got was from using a knife hand to break a stack of tiles while Kung Fu training. It wasn’t the tiles that did the damage; it was my failure to pull up before hitting and cracking the wooden floor! I was 26 then. My little finger hamate bone healed quickly, and I was training again full contact inside a month.
In contrast I’ve also seen many vegan and vegetarian children raised without dairy products. The common observation is weak bones and teeth, and I have yet to see an exception to this.
If you don’t display health problems from milk, I would suggest drinking it while you are young. If you don’t and you find later in life that calcium absorption is poor, then the best and easiest form of calcium may not be available to you. You simply may not have the enzymes to assimilate the mineral. Something that also should be remembered is that actions of many recreational drugs result in cells utilizing more calcium.
In regards to cats; I seem to remember reading that cats lack some lactases required for metabolism, so it’s hardly surprising cow’s milk is not very good for them. We generally don’t give our cats milk, except on occasion as a medicine.
Getting back to tryptophan; current methods of pasteurizing using heat would not destroy much if any tryptophan, with any probable product being a small amount of tryptamine, itself an active LSD like compound, although orders of magnitude less in potency.
