Micro/Biology

» carpentershop - Cleaning of granite countertops

We sell all types of countertops, but lately with all the bacteria illness outbreaks, we are looking closer into how well granite tops can be cleaned. The granite lobby group, MIA, did one study, but it seemed self serving at best, suspect at worst.

Anyone have any info on bacteria survival rates on natural stone surfaces? We have started some informal testing using coliscan test kits that really have us worried about continuing to sell granite.

Thanks all for any help.

Al

-- posted by carpentershop

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» Judy Arbique - Cleaning of granite countertops

In response to Cleaning of granite countertops posted by carpentershop:

Gee, I guess you can't take anything for "granite"!!!
Sorry, I couldn't resist. I have encountered a lot of claims from companies who distribute granite countertops and competitors of granite countertop distributors, but there seems to be very little accurate helpful information to answer your concerns.

Granite is a natural porous material that may have deep cracks and fissures where bacteria can hide out, but so can plastics and other materials whose surfaces have been damaged. A study published in the Journal of Food Protein in October, 2006 did find that salmonella adhesion rates were greater on granite than on plastic surfaces, and was related to hydrophobicity of the surface.

At this point, I have not found sufficient information that would cause me to avoid considering granite countertops. Despite the composition of your counter-top, it is advisable to clean it thoroughly and frequently, and to prepare foods on a cutting board that can then be thrown in the dishwasher before reusing.

Source:
Oliveira K et al. Comparison of the Adhesion Ability of different Salmonella enteritidis serotypes to materials used in kitchens.J Food Prot. 2006 Oct;69(10):2352-6.

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» carpentershop - Cleaning of granite countertops

In response to Cleaning of granite countertops posted by carpentershop:

Thanks for the reply and the article. It was very helpful.

Makes sense, damaged or scratches giving a haven for the critters. The solid surface is usually sanded down to about 30 microns, some times it is mirror polished. But I guess the bacteria are even smaller than that.I need to buy that article on the roughness of the surface of materials and bacteria.

Thanks for all the help, might have another question one of these days if you don't mind helping out again.
Al

-- posted by carpentershop

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» Judy Arbique - Cleaning of granite countertops

In response to Cleaning of granite countertops posted by carpentershop:

Love to hear from you again...good luck polishing those countertops!

judy

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» carpentershop - Cleaning of granite countertops

In response to Cleaning of granite countertops posted by arbiquej:

Miss Judy, I have a couple of questions when you get the time to reply.

First is a a reference to hydrophobicity which I understand to mean that it doesn't bond well with water. The study refers to all materials being hydrophobic, with granite having a low degree of hydrophobicity.

I am confused, wouldn't a low level mean that it would repel water, or the water would bead up on the surface? Since we work with granite using water as a lubricant and coolant, I know that granite soaks up water like a sponge, actually turns darker and takes several days to dry out. I understood hydrophobicity to be like oil in water, neither mixing without some help. I understand that cells can have hydrophobic and hydrophillic components, which makes sense.

Second question is a referencein the study to Salmonella Enteritidis EMB and Salmonella Enteritidis MUSC. This was a joint Brazilian and Portugese study aparently, so they may have different names, but I haven't found any reference to these strains so far on the internet.
Supposedly, they cultured the SE Emb out of chicken juice out of a chicken carcass and the MUSC was cultured out of a chicken breast muscle.

Seems the MUSC has a propensity to adhere to polyeproplyne in almost double quanities, while the EMB adheres to granite 3.5 to 7 times more than the plastics tested in the study. Neither of these are common countertop materials, but are common in food prep utinsels.

Is there a site that covers the strains of Salmonella Enteritidis?

Is my understanding of hydrophobicity way off?

Thanks, Al.

-- posted by carpentershop

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» Judy Arbique - Cleaning of granite countertops

In response to Cleaning of granite countertops posted by carpentershop:

Your understanding of hydrophobicity is right on! The article mentioned that granite has a low degree of hydrophobicity....it doesn't repel water like some of the other surfaces tested.

I have included a link below that might help your understanding of different strains of Salmonella enteritidis:
http://www.cdc.gov/search.do?queryText=e...

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» carpentershop - Cleaning of granite countertops

In response to Cleaning of granite countertops posted by arbiquej:

Hi again Judy,
I ran across this study that showed 100,000 bacteria per gram of stone being recovered from a desert outcropping of granite. Seems relevant since it points to either bacteria reproducing or some "unknown" method of transporting bacteria deep into the stone.

What do you think about this study? Any weak points in it?

http://www.pubmedcentral.nih.gov/article...

-- posted by carpentershop

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» Judy Arbique - Cleaning of granite countertops

In response to Cleaning of granite countertops posted by carpentershop:

I didn't see anything in the article that alarmed or surprised me...any natural surface is likely to harbour bacteria especially if it originates in the ground. I would think it would be almost impossible to sterilize stone...whether it be granite, limestone or other natural stone.

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