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Water activity and shelf life

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Is it possible to use the water activity value of a ganache to estimate a potential shelf life of that ganache?

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Yes. If you have the aW numbers, Wybauw has corresponding shelf life estimates. 

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Yes, it is. Or at least knowing the water activity can provide an estimate of shelf life (about the only indicator there is, aside from just keeping ganache for a while and checking it for spoilage from time to time). Jean-Pierre Wybauw gives the following guide for how long a ganache can be safely kept: 

     for an Aw greater than 0.85:  maximum of 3 weeks

     for an Aw between 0.70 and 0.85:  maximum of 3 months

     for an Aw between 0.65 and 0.70:  maximum of 9 months

     for an Aw below 0.65:  "the ganache is microbially stable" (I'm assuming that basically means "forever")

 

I operate on the general principle that the Aw must always be below 0.85, with the goal of getting it as low as possible. In the U.S. some states have specific regulations that nothing at 0.85 or higher can legally be sold.


Edited by Jim D. (log)
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 But keep in mind it doesn't mean that the product will still taste good! There are some other factors besides available water that will determine the palatability of a ganache after a number of months.


Edited by Kerry Beal (log)

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To add to what I said above:  If a shelf life of 3 weeks sounds like a "no problem" situation, it isn't. I talked to someone a couple of days ago who received a box of my chocolates as a Christmas gift. She proudly announced that she is still (this was on Feb. 10) enjoying them, one piece per day! That is the sort of information that keeps me vigilant and led me to purchase a water activity meter. No one has any control over what the recipient does with the bonbon. And that is why I would never produce a bonbon such as the crème brûlée one sold by a famous NYC chocolatier (who, I have read, tells customers to consume it within a day or so). And finally, it is why I purchased food insurance.

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8 minutes ago, Kerry Beal said:

 But keep in mind it doesn't mean that the product will still taste good! There are some other factors besides available water that will determine the palatability have a ganache after a number of months.

 

Definitely true. There is a drying out and shrinking of the ganache that happens as well as a fading of the flavor.

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On 2/13/2018 at 8:51 AM, Jim D. said:

To add to what I said above:  If a shelf life of 3 weeks sounds like a "no problem" situation, it isn't. I talked to someone a couple of days ago who received a box of my chocolates as a Christmas gift. She proudly announced that she is still (this was on Feb. 10) enjoying them, one piece per day! That is the sort of information that keeps me vigilant and led me to purchase a water activity meter. No one has any control over what the recipient does with the bonbon. And that is why I would never produce a bonbon such as the crème brûlée one sold by a famous NYC chocolatier (who, I have read, tells customers to consume it within a day or so). And finally, it is why I purchased food insurance.

Which meter did you purchase and are you happy with it?

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1 hour ago, Bentley said:

Which meter did you purchase and are you happy with it?

 

I have the Aqualab Pawkit, used by several on this forum. Aqualab has now become Meter Group, but I think the Pawkit is still sold, though they are emphasizing more expensive equipment now (the Pawkit is labeled a "legacy" product). I am happy with it. It's accurate to within + or -0.02 (which is enough for me). Warning: it is not inexpensive.

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37 minutes ago, Jim D. said:

Warning: it is not inexpensive.

 

Yeah, I got a quote last month, had some holiday cash flow to splurge with, but with a base price of $2400 plus vials, sample cups, and sales tax, I opted for bar codes, an EZ Temper, AND a 24kg melter instead.

 

On 2/13/2018 at 5:51 AM, Jim D. said:

To add to what I said above:  If a shelf life of 3 weeks sounds like a "no problem" situation, it isn't. I talked to someone a couple of days ago who received a box of my chocolates as a Christmas gift. She proudly announced that she is still (this was on Feb. 10) enjoying them, one piece per day! That is the sort of information that keeps me vigilant and led me to purchase a water activity meter. No one has any control over what the recipient does with the bonbon.

 

This, to infinity.  Yes, we probably all should have water meters and err on the side of caution with best by dates.  I'm limiting my wholesale line to bars, gianduja, and caramel that I'm sure are safe and keeping the bonbons in the fridge to sell directly.  It's still on my wish list, but the other items were more useful for my current production.

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