What is Aw (water available)?

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sambal badjak
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Post by sambal badjak » Fri Sep 13, 2013 11:56

Thanks ChuckW
I am looking for the emoticon of a thumbs up, as you need a huge one for your help and patience !!!!!

Another question, based on your post above:
How do you measure Aw?

Can you weigh the meat, use a dry brine, weigh again and work out the proportion?
Say: your meat weight 1000 gr. After (dry) brining it the weight is 950 gram -> Aw is 0.95 ???
life is too short to drink bad wine (anonymus)
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Chuckwagon
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Post by Chuckwagon » Fri Sep 13, 2013 13:21

"Battling Bugs By Restricting Their Available Water"

I`ve chuckled and snickered at Kjuncatman`s `signature` on our forum since the first day I read it. It says, "Cure the meat? Is it sick?" If the world were depending upon you to eliminate pathogenic bacterial microorganisms, just how would you go about it? Can you think of the cheapest effective means to snuff `em out? You could starve `em out couldn`t you? If you dried up their food, they would expire... right? You know that bacteria cannot survive in an environment without moisture, so might it be possible to limit the amount of water available to bacteria in order to destroy them? And, what about salt? What does it do and how much would you use? All good questions! However, contrary to popular certainty, salt does not destroy bacteria. It doesn`t even force water to evaporate. It does, however, immediately immobilize or bind a specific, large amount of free water, preventing it from interacting with bacteria (or anything else). The measurement of "bound" water (not available to bacteria) is called "water activity", and is abbreviated Aw. Water Activity is measured on a scale from 0.00 (called "bone dry") to 1.00 - the measurement of pure water. So, how about serving a bacterium a dose of salt at first, while we deprive it of moisture? It works. For thousands of years it has worked! Bacon, hams, sausages, and all sorts of meat have been cured with salt, smoked, and dried safely for centuries. Your grandparents certainly knew that salting, drying, and par-cooking meats were positive steps adverse to microorganism survival! They were also aware that if they smoked meat, it not only tasted better but it was not likely to develop mold on its surface.

Sambal, Aw is measured professionally and accurately using an expensive meter. We poor home sausage benders mostly use a very accurate scale for the weight of the meat product as it dries. Each recipe usually states the preferred "yield" weight - at which a loss of about 30% moisture (or more) is involved.

There is much more information posted concerning Aw and pH in the technical forum on this site if you are interested in it. However, don't quit writing to us and asking questions. We look forward to your questions and comments. Keep up the good work girl!

Best Wishes,
Chuckwagon
If it looks like a duck, walks like a duck, and quacks like a duck, it probably needs more time on the grill! :D
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