Wood’s anti-bacterial properties
Andre Willers
20 Apr 2013
Synopsis :
Wood does inhibit bacterial growth , but it takes about 4
days . Much quicker to microwave it .
Discussion :
1.The empirical , experimental data is rock-solid . Wooden
cutting boards in the kitchen are much better than any other surface .
Bacterial counts decrease exponentially . Something (presumably the physical
structure) prevents bacteria from multiplying . Unfortunately , this means that bacterial
contamination only becomes less than dangerous levels after about 4 days . It
seems to work by isolating bacteria into little valleys in the physical
structure of the wood . The bacteria apoptose because of lack of
inter-bacterial communication .
See Appendix B and Google it .
2. Cheat :
Just microwave it . See Appendix A . Purely empirical .
Total elimination of bacteria on wood after 4 min of high
microwave for a 500 g wooden board , but very little for plastic surfaces .
3.Why ?
Hills and valleys . Wood has a physical structure like the Himalayas
, while the plastics is more like a rolling meadow .
Bacteria get lodged into the valleys of wood , then the
water in the surrounding structures get vaporized into steam jets that puncture
the bacterium’s cell wall and kills it .
Without the
entrapment , the temperature spike is
not concentrated , but simply passed along to the environment . Very
efficiently too , judging from Appendix A .
You are looking at super-conduction of heat by
food-poisoning bacteria . A very neat trick with billions of $ of applications
.
How did this develop ?
Fever . The body increases temperature to kill bacteria ,
and evolutionary pressures force the bacteria to pass along the energy .
4. How ?
Very fine tubules between cells .
See:
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News
and Views
Nature Cell Biology 6,
281 (2004)
doi:10.1038/ncb0404-281
doi:10.1038/ncb0404-281
Getting connected
Alison Schuldt
The ways in which cell–cell communication is
achieved are many and varied: they can include indirect communication through
extracellular signalling molecules, or a direct physical link such as a gap
junction, an immunological or neural synapse. Reporting in the February 13
issue of Science, Hans-Hermann Gerdes and colleagues now describe a
new intercellular connection — long actin-based nanotubules that form de
novo between cells in culture.
Xxx
Actually , quite well known . These nanotubules contain strands
of temperature superconductors . For food poisoning bacteria in any case . If
the bacteria are isolated , then they are vulnerable to temperature pulses as
described in Appendix A .
These should be easy to isolate , get the DNA and use
genetic engineering to manufacture them on large scale .
The dear reader will note the close relationship between a
superconductor of heat and a superconductor of electricity .
5. Cancers :
This mechanism has been hi-jacked long ago by cancer cells .
But there is a twist in the tale . This means that the energy can be tapped out
of a tumour even by fairly low temperature applied over a long time .
6. Body building :
Or humans can sculpt muscles and fat by applying heat-sinks at
specific spots on the body for a few minutes a day .
There are fancy high-tech ways of doing this .
The poor man’s way is simply to put your hairbrush in the
freezer . Then press the frozen hairbrush on the bit you want to reduce .
That’s it .
7. Brushing your hair with a frozen hair brush should have
interesting results . It sucks energy out of bad things . Should help with
tumours , bad memories (PTSD) , your last girl friend . Increase IQ by about 15
points . Try it .
8. Heating hairbrushes : your guess is as good as mine .
Been done for a long time .
“She asks me why, I'm just a hairy guy.
I'm hairy noon and night, hair that's a fright.”
I'm hairy noon and night, hair that's a fright.”
“Give me a head with hair, long beautiful hair.
Shining, gleaming, streaming, flaxen, waxen.
Give me down to there hair, shoulder lenght or longer
Here baby, there, momma, ev'rywhere, daddy, daddy.”
Shining, gleaming, streaming, flaxen, waxen.
Give me down to there hair, shoulder lenght or longer
Here baby, there, momma, ev'rywhere, daddy, daddy.”
Huga-bugga
.
Andre .
xxxx
Appendix A
This says it all
Abstract:
Used
cutting boards with numerous knife marks, particularly those made of polymers,
are difficult to disinfect manually. Plastic cutting boards have been preferred
to wood because they can be washed in dishwashers and used in microwave ovens.
Our study tested the microwave oven for disinfection of cutting boards.
Surfaces of plastic and wooden cutting boards were inoculated with up to 109 CFU of Escherichia
coli or other bacteria in broth culture and later sampled by contact
with agar medium for CFU assay or by swabbing for ATP bioluminescence assay. On
wood, almost total elimination of vegetative cells occurred with exposure times
of the 3 to 4 min at a high setting on typical 450 to 600 g wooden boards,
depending on board size, bacterial load, and moisture level. On plastic,
microwave energy had almost no lethal effect on bacteria: 12 min of exposure
did not reduce the number of bacteria significantly. Increased moisture
(wetness) enhanced killing efficiency on wood, but was negligible on plastic.
Temperatures near the wood surface reached 95°C within the first 4 min, whereas
plastic surfaces reached no more than 40°C. Our study indicates that brief
"cooking" of wooden boards at a "high" setting in a
microwave oven is an effective way to kill bacteria, and thus a very simple and
cheap method to protect food against cross-contaminating pathogens. Because
plastic is relatively inert to microwaves, disinfection of plastic boards in a
microwave oven is impractical.
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Appendix B
Empirical data . Wood has definite anti-bacterial effect .
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PLASTIC AND WOODEN CUTTING BOARDS
Dean O. Cliver, Ph.D.
We began our research comparing plastic and wooden cutting
boards after the U.S. Department of Agriculture told us they had no
scientific evidence to support their recommendation that plastic, rather than
wooden cutting boards be used in home kitchens. Then and since, the U.S.
Department of Agriculture's Meat and Poultry Inspection Manual (official
regulations) and the U.S. Food and Drug Administration's 1995 Food Code
(recommended regulations for restaurants and retail food sales in the various
states of the U.S.) permit use of cutting boards made of maple or similar
close-grained hardwood. They do not specifically authorise acceptable plastic
materials, nor do they specify how plastic surfaces must be maintained.
Our research was first intended to develop means of
disinfecting wooden cutting surfaces, so that they would be almost as safe as
plastics. Our safety concern was that bacteria such as Escherichia coli
O157:H7 (commonly known as E-coli) and Salmonella, which might contaminate a
work surface when raw meat was being prepared, ought not remain on the
surface to contaminate other foods that might be eaten without further
cooking. We soon found that disease bacteria such as these were not
recoverable from wooden surfaces in a short time after they were applied,
unless very large numbers were used. New plastic surfaces allowed the
bacteria to persist, but were easily cleaned and disinfected. However, wooden
boards that had been used and had many knife cuts acted almost the same as
new wood, whereas plastic surfaces that were knife-scarred were impossible to
clean and disinfect manually, especially when food residues such as chicken
fat were present.
Although the bacteria that had disappeared from the wood
surfaces were found alive inside the wood for some time after application,
they evidently do not multiply, and they gradually die. They can be detected
only by splitting or gouging the wood or by forcing water completely through
from one surface to the other. If a sharp knife is used to cut into the work surfaces
after used plastic or wood has been contaminated with bacteria and cleaned
manually, more bacteria are recovered from a used plastic surface than from a
used wood surface.
"Manual cleaning" in our experiments has been
done with a sponge, hot tap-water, and liquid dishwashing detergent.
Mechanical cleaning with a dishwashing machine can be done successfully with
plastic surfaces (even if knife-scarred) and wooden boards especially made
for this. Wooden boards, but not plastics, that are small enough to fit into
a microwave oven can be disinfected rapidly, but care must be used to prevent
overheating. Work surfaces that have been cleaned can be disinfected with
bleach (sodium hypochlorite) solutions; this disinfecting is reliable only if
cleaning has been done successfully.
The experiments described have been conducted with more
than 10 species of hardwoods and with 4 plastic polymers, as well as hard
rubber. Because we found essentially no differences among the tested wood
species, not all combinations of bacteria and wood were tested, nor were all
combinations of bacteria and plastics or hard rubber. Bacteria tested, in
addition to those named above, include Campylobacter jejuni, Listeria
monocytogenes, and Staphylococcus aureus.
We believe that the experiments were designed to be
properly representative of conditions in a home kitchen. They may or may not
be applicable to other plastic and wooden food contact surfaces or to cutting
boards in commercial food processing or food service operations, but we have
no reason to believe that they are not relevant, except that not all plastic
surfaces are subject to knife-scarring. Before our first studies had been
published, they were criticised incorrectly for not having included used
(knife-scarred) cutting surfaces. We had been careful to include used
surfaces, and so were surprised that others who did later experiments and
claimed to have refuted our findings often had used only new plastic and
wood. Although some established scientific laboratories say their results
differ from ours, we have received multiple communications from school
children who have done science projects that have reached essentially the
same conclusions that we did.
We have no commercial relationships to any company making
cutting boards or other food preparation utensils. We have tested boards and
cleaning and disinfecting products, some of which were supplied to us gratis.
We have not tested all of the products that have been sent to us, simply
because there is not time. We are aware that there are other food preparation
surfaces made of glass or of stainless steel; we have done very little with
these because they are quite destructive of the sharp cutting edges of
knives, and therefore introduce another class of hazard to the kitchen. We
believe, on the basis of our published and to-be-published research, that
food can be prepared safely on wooden cutting surfaces and that plastic
cutting surfaces present some disadvantages that had been overlooked until we
found them.
In addition to our laboratory research on this subject, we
learned after arriving in California in June of 1995 that a case-control
study of sporadic salmonellosis had been done in this region and included
cutting boards among many risk factors assessed (Kass, P.H., et al., Disease
determinants of sporadic salmonellosis in four northern California counties:
a case control study of older children and adults. Ann. Epidemiol. 2:683-696,
1992.). The project had been conducted before our work began. It revealed
that those using wooden cutting boards in their home kitchens were less than
half as likely as average to contract salmonellosis (odds ratio 0.42, 95%
confidence interval 0.22-0.81); those using synthetic (plastic or glass)
cutting boards were about twice as likely as average to contract
salmonellosis (O.R. 1.99, C.I. 1.03-3.85); and the effect of cleaning the
board regularly after preparing meat on it was not statistically significant
(O.R. 1.20, C.I. 0.54-2.68). We know of no similar research that has been
done anywhere, so we regard it as the best epidemiological evidence available
to date that wooden cutting boards are not a hazard to human health, but
plastic cutting boards may be.
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Publications to date from our work:
Ak, N. O., D. O. Cliver, and C. W. Kaspar. 1994. Cutting
boards of plastic and wood contaminated experimentally with bacteria. J. Food
Protect. 57:16- 22.
Ak, N. O., D. O. Cliver, and C. W. Kaspar. 1994.
Decontamination of plastic and wooden cutting boards for kitchen use. J. Food
Protect. 57:23-30,36.
Galluzzo, L., and D. O. Cliver. 1996. Cutting boards and
bacteria--oak vs. Salmonella. Dairy, Food Environ. Sanit. 16:290-293.
Park, P. K., and D. O. Cliver. 1996. Disinfection of
household cutting boards with a microwave oven. J. Food. Protect.
59:1049-1054.
Others are in press or in preparation.
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Dean O. Cliver, Ph.D.,
Professor, Department of Population Health and Reproduction School of Veterinary Medicine University of California |
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