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Water Activity/Shelf LIfe


Sweet Impact Mama
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I was wondering what process you guys follow for assessing shelf life? Do you just base it on the water activity or do you do full shelf life tests as well?

 

Or perhaps another process?

 

 

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22 minutes ago, DomDeFranco said:

I was wondering what process you guys follow for assessing shelf life? Do you just base it on the water activity or do you do full shelf life tests as well?

 

Or perhaps another process?

 

 

 

Honestly so far I've been winging it and guesstimating 😳   But I feel like I can't afford to do that anymore.

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2 minutes ago, pastrygirl said:

 

Honestly so far I've been winging it and guesstimating 😳   But I feel like I can't afford to do that anymore.

Yeah, I'm working on some marketing materials for wholesale customers and was initially hoping I could base shelf life on water activity alone. There's such a huge variation in what different AW's correspond to in terms of shelf life though, that basing your shelf life solely on AW, especially if you're looking at longer shelf lives for wholesale customers seems potentially problematic.

 

For an AW of .80 say, Confectionary & Chocolate Engineering has it at 27 days, Pro-Choc says 124-137 days, Melissa Coppel says 35-42 and J.P. Wybauw reckons up to 91 days between 0.70 - 0.85, which is pretty hard to decipher.

 

From Confectionary & Chocolate Engineering:

 

"Enzymatic activity starts at about aw =0.3, mould growth starts at about aw =0.75,
yeast growth starts at aw =0.8 and bacterial growth starts at aw =0.9 – all these
four types are stimulated by an increase in aw.
"

 

I've saw different ranges for these categories in different books as well! 

 

0.75 seems to be a good AW to aim for and then maybe have a more limited menu that changes more slowly, that you can be sure of for wholesale customers.

 

I'd be interested to know what AW's people are aiming for and what they market the shelf life as?

 

Thanks

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1 hour ago, DomDeFranco said:

I was wondering what process you guys follow for assessing shelf life? Do you just base it on the water activity or do you do full shelf life tests as well?

 

Or perhaps another process?

 

 

 

Basically I follow Melissa's numbers (life would be impossible if I didn't make some sort of decision on what to follow).  I test the Aw of all recipes, and if there are some I particularly like that are above 0.80, I work to get them lower.  I am now emphasizing more than previously that there is a shelf life, since many customers are going by the "this will last forever" rule of commercial bonbons.  For wholesale outlets, I insist they have refrigeration, preferably a freezer as well, and periodically refresh their memory of how to handle chocolates; I also make more frequent deliveries--a nuisance but better that than a mold episode.  Like pastrygirl, I find myself using more caramel and gianduja fillings.  For retail customers, I provide temperature recommendations and correct storage methods.  If a customer cannot pick up chocolates for a longer than desirable period of time, I seal the box(es) in plastic and refrigerate them, freeze them if the time is substantial.  And my most recent addition is the use of sorbic acid; unfortunately this works only in acidic environments, but I would add it to, for example, passion fruit and all fruit ganaches, and all pâte de fruit fillings.

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It's also useful to do a standing study on your pieces - store in different conditions and cut into a piece each week until you determine when they are gone. Not all shelf life is Aw related - sometimes the flavor goes off, sometimes they saponify - still safe to eat but taste like crap. 

 

An Aw of 0.75 is theoretically ideal - doesn't take on or lose water to the environment. 

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6 hours ago, Kerry Beal said:

You can pick the amount of time?


the Rotronic has a ‘quick’ option that you can set the dwell time on and should be within 0.005 of the full analysis. I had not run a full one yet, am doing that now. It just finished, that sample took half an hour and was 0.003 different from the previous ‘quick’ reading.  
 

my goal is 0.75 or below, if above that is where mold starts to grow and if that’s what Kerry says is good ;)

 

and then I have some flavors like white chocolate caramel that is 0.70 & keeps a long time but starts to look dull after a few months at room temp from butterfat seeping through. Theres always something else 😆

Edited by pastrygirl (log)
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8 hours ago, pastrygirl said:


the Rotronic has a ‘quick’ option that you can set the dwell time on and should be within 0.005 of the full analysis. I had not run a full one yet, am doing that now. It just finished, that sample took half an hour and was 0.003 different from the previous ‘quick’ reading.  
 

my goal is 0.75 or below, if above that is where mold starts to grow and if that’s what Kerry says is good ;)

 

and then I have some flavors like white chocolate caramel that is 0.70 & keeps a long time but starts to look dull after a few months at room temp from butterfat seeping through. Theres always something else 😆

Of course I make lots of fillings that have an Aw in the 8's and they still seem to have a wonderfully long shelf life in spite of what the numbers would say. And other's as @pastrygirl says that have a nice low number but sugar bloom or fat bloom make them look like crap in a short time while they are still safe to eat. 

 

Here's what I assembled and used in a talk I gave at Tomric years ago.  It's not how long things will last - more what things are likely to affect your product. 

 

< 0.61 - safe from osmotic yeasts

< 0.65 - safe from xerophilic fungi (fungi that grow in low water conditions)

< 0.80 - safe from regular fungi

< 0.85 - safe from Staphlococci

< 0.88 - safe from regular yeasts

< 0.94 - safe from non pathogenic bacteria

< 0.95 - safe from pathogenic bacteria

 

Then I assembled kind of a general guestimate of shelf life

 

> 0.85 - up to 3 weeks

0.7 - 0.85 - up to 3 months

0.65 - 0.7 - 6 to 9 months

< 0.60 - microbiologically stable 

 

And here were some examples of various products I put together at the time 

 

chocolate and gianduja - aW < 0.3

caramel # - aW < 0.48

marzipan# - aW 0.65 - 0.70

fondant# - aW 0.75 - 0.84

buttercreams# - aW 0.81 - 0.87

ganache no additives - aW 0.9 - 0.95 

 

 

 

 

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1 hour ago, Kerry Beal said:

Of course I make lots of fillings that have an Aw in the 8's and they still seem to have a wonderfully long shelf life in spite of what the numbers would say. And other's as @pastrygirl says that have a nice low number but sugar bloom or fat bloom make them look like crap in a short time while they are still safe to eat. 

 

Here's what I assembled and used in a talk I gave at Tomric years ago.  It's not how long things will last - more what things are likely to affect your product. 

 

< 0.61 - safe from osmotic yeasts

< 0.65 - safe from xerophilic fungi (fungi that grow in low water conditions)

< 0.80 - safe from regular fungi

< 0.85 - safe from Staphlococci

< 0.88 - safe from regular yeasts

< 0.94 - safe from non pathogenic bacteria

< 0.95 - safe from pathogenic bacteria

 

Then I assembled kind of a general guestimate of shelf life

 

> 0.85 - up to 3 weeks

0.7 - 0.85 - up to 3 months

0.65 - 0.7 - 6 to 9 months

< 0.60 - microbiologically stable 

 

And here were some examples of various products I put together at the time 

 

chocolate and gianduja - aW < 0.3

caramel # - aW < 0.48

marzipan# - aW 0.65 - 0.70

fondant# - aW 0.75 - 0.84

buttercreams# - aW 0.81 - 0.87

ganache no additives - aW 0.9 - 0.95 

 

 

 

 

 

This is a great resource, very helpful.  The only figure I wonder about is the final one.  By "no additives" do you mean no ingredients other than chocolate plus liquid or (more probably) no additives such as invert sugar?  

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47 minutes ago, Jim D. said:

 

This is a great resource, very helpful.  The only figure I wonder about is the final one.  By "no additives" do you mean no ingredients other than chocolate plus liquid or (more probably) no additives such as invert sugar?  

Yup - essentially cream and chocolate - of course it doesn't account for amounts.

 

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Interesting. I have several molded pieces filled with ganache that last for 2+ months. They still taste good & look good. I wouldn't sell them to anyone but test pieces that past the look & sniff tests do get consumed by my husband and me. I tell customers to enjoy, no preservatives, consume within two weeks.

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back to the info Dom found - here I've added some graph lines to intersect at  21C/70F (room temp) and 10C/50F (display fridge temp) for 0.75, 0.80, and 0.85. 

 

 

512350768_shelflife2.thumb.jpg.49ef802a77b74449087ee38aec31c3ed.jpg

 

 

 

Of course all this is approximate, there are other factors, etc, but I'm feeling like 0.80 is too high for my customers who keep things at room temp, I want them to have at least 4-6 weeks.  In better news, if a 0.75 bonbon will stay mold free 10+ months at 10C, do we ever need to freeze them?  Sometimes I have more freezer than fridge space, but maybe I don't have to worry so much about how long bonbons are in my reach-in fridge at 3C/37F? 

 

 

 

 

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7 hours ago, pastrygirl said:

back to the info Dom found - here I've added some graph lines to intersect at  21C/70F (room temp) and 10C/50F (display fridge temp) for 0.75, 0.80, and 0.85. 

 

 

512350768_shelflife2.thumb.jpg.49ef802a77b74449087ee38aec31c3ed.jpg

 

 

 

Of course all this is approximate, there are other factors, etc, but I'm feeling like 0.80 is too high for my customers who keep things at room temp, I want them to have at least 4-6 weeks.  In better news, if a 0.75 bonbon will stay mold free 10+ months at 10C, do we ever need to freeze them?  Sometimes I have more freezer than fridge space, but maybe I don't have to worry so much about how long bonbons are in my reach-in fridge at 3C/37F? 

 

 

 

 

Yeah, that chart clearly shows the massive difference temperature has on shelf life. It would have been nice if they Included fridge temperature in their experiment but I guess that wasn't their focus at the time.

 

I think the guidelines @Kerry Beal devised for shelf life estimates for different confections are really useful. I was wondering where you guys would put a pate de fruit in there?

 

My conclusion to all this, for what it's worth, is that for the more shelf stable products like caramels, giandujas etc, basing shelf life estimates on AW is fine, but when it comes to ganache with cream and fruit etc you really have to do a full shelf life test and just test them yourself (at similar storage conditions to your customers) every week or so until the shelf life period you're looking for is over.

 

For yourself and the more experienced chocolatiers, who have fairly stable recipes for the different type of ganaches and products etc, I think you'll be able to come up with fairly accurate shelf life estimates for new products based on what you've made before.

 

For those of us like myself who are still fairly new to it all, we'll just have to do full shelf life tests for the higher AW items on our menus, until we have that bank of recipes and experience.

 

At the moment I'm being very cautious and claiming 2 weeks at 21 degrees and under as that's all I've tested for.

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Great discussion and info here! I've got a Humimeter RH2 Aw meter, and I've been wondering a lot about the values I get. It should be accurate to 0.01 values (0.04 around 0.80-0.98 though), and when testing the recipes over again, it gets around the same result. But when testing recipes from different (reliable) sources where they've given the Aw value, I'm rarely getting even close to it. Most simple example: recipe with 45g cream (36% fat), 5g glucose, 55g hazelnut praline (50-50), 45g milk chocolate (36% cocoa). Author is saying it's Aw 0.75, I got 0.80. Which is a huge difference, and even if my machine's error made it 0.80 instead of 0.79 for example, it'd still be a big difference. Same thing has happened with other recipes too, with +0.05 differences between my and the authors' Aw values.

 

There's been discussion previously about how you measure also matters. I let the samples come to room-temp, and mix them before measuring to avoid artificially low readings due to drying on top of the sample. Also filling the measurement jars as instructed by the manufacturer. My room-temp is currently very cold, around 17C. I'm not sure whether that could impact, though I'd think not if the sample is the same temp as the room. 

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On 3/23/2022 at 6:29 PM, pastrygirl said:

 

I got the Lindt 70% & tested (at 20.6C for 4 min)

 

4:1 choc:H20 = 0.788 ... very firm though, wouldn't want it in a bonbon.  But a similar aW with added butter fat would be softer, right?

 

2:1 = 0.946

 

 

 

Following up, I just noticed mold in my 2:1 sample cup, that didn't take long at all!

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Well I took one for the team. Since I'm stuck at home unless I can get a ride to work because of this damn boot I've had time to get some stuff done and spend some money.

 

I'm often asked about these 'cheap' Aw meters on Amazon and I decided it was time I got my hands one one and ran it through it's paces. 

 

WA-160A

 

I was too cheap to buy it from Amazon - so I purchased from a vendor on Aliexpress - cost me $508 CDN plus another $35 dollars in duties/tax - had I purchased on Amazon.ca it would have cost me min $754 plus $98 in tax. 

 

So I pulled out my PAwkit - a 0.76 standard and made a couple of ganaches - 150 grams of 56% dark with 75 grams of cream and 150 grams chocolate with 100 grams of cream. 

 

The standard read 0.76 on both the PAwkit and the WA-160A so off to a good start. It can be calibrated if the standard is off. It doesn't come with standards but you can make your own or purchase from Decagon. I should have checked distilled water on both but I'm not sure I have any here. 

 

The one ganache was 0.71 on PAwkit and 0.73 on WA-160A - other ganache was 0.86 on PAwkit and 0.85 on the WA-160A - repeat readings on each were within 0.01 each time. 

 

IMHO it works just as well as my PAwkit. 

 

It comes with 3 lidded sample vials - I can use the disposable ones from the PAwkit in it but they are kinda tight so for liquids I need to take care around splashing. Also it 'snaps' together magnetically which is fine with solids but with liquids can cause splashing in to the instrument so stabilizing the bottom before bringing down the top is a wise idea. 

 

Making your own 6 mol NaCl solution - 100g pure NaCl, add into 200g hot distilled water, stir it. Cool to room temperature. 2. Keep the solution into a brown bottle for one week at room temperature. The solution AW value should be 0.75~0.77

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16 hours ago, Kerry Beal said:

Well I took one for the team. Since I'm stuck at home unless I can get a ride to work because of this damn boot I've had time to get some stuff done and spend some money.

 

I'm often asked about these 'cheap' Aw meters on Amazon and I decided it was time I got my hands one one and ran it through it's paces. 

 

WA-160A

 

I was too cheap to buy it from Amazon - so I purchased from a vendor on Aliexpress - cost me $508 CDN plus another $35 dollars in duties/tax - had I purchased on Amazon.ca it would have cost me min $754 plus $98 in tax. 

 

So I pulled out my PAwkit - a 0.76 standard and made a couple of ganaches - 150 grams of 56% dark with 75 grams of cream and 150 grams chocolate with 100 grams of cream. 

 

The standard read 0.76 on both the PAwkit and the WA-160A so off to a good start. It can be calibrated if the standard is off. It doesn't come with standards but you can make your own or purchase from Decagon. I should have checked distilled water on both but I'm not sure I have any here. 

 

The one ganache was 0.71 on PAwkit and 0.73 on WA-160A - other ganache was 0.86 on PAwkit and 0.85 on the WA-160A - repeat readings on each were within 0.01 each time. 

 

IMHO it works just as well as my PAwkit. 

 

It comes with 3 lidded sample vials - I can use the disposable ones from the PAwkit in it but they are kinda tight so for liquids I need to take care around splashing. Also it 'snaps' together magnetically which is fine with solids but with liquids can cause splashing in to the instrument so stabilizing the bottom before bringing down the top is a wise idea. 

 

Making your own 6 mol NaCl solution - 100g pure NaCl, add into 200g hot distilled water, stir it. Cool to room temperature. 2. Keep the solution into a brown bottle for one week at room temperature. The solution AW value should be 0.75~0.77

Thanks for doing this. I've ordered one of them from alibaba so with your and @Rajala's results it seems they're up to the job!

 

Good stuff :)

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  • 3 weeks later...

In Wybauw's Fine Chocolates 2, he writes about increasing shelf life by adding ingredients that bind water, especially sorbitol and corn syrup/glucose.  He mentions "adding 50% corn syrup to the moisture quantity in ganaches".  Do you agree that the 'moisture quantity' is whatever amount of water is in the cream or purees, so 100 g of 40% fat cream adds 60 g 'moisture' that would be bound by 30 g glucose? 

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6 hours ago, pastrygirl said:

In Wybauw's Fine Chocolates 2, he writes about increasing shelf life by adding ingredients that bind water, especially sorbitol and corn syrup/glucose.  He mentions "adding 50% corn syrup to the moisture quantity in ganaches".  Do you agree that the 'moisture quantity' is whatever amount of water is in the cream or purees, so 100 g of 40% fat cream adds 60 g 'moisture' that would be bound by 30 g glucose? 

Correct

 

 

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6 hours ago, pastrygirl said:

In Wybauw's Fine Chocolates 2, he writes about increasing shelf life by adding ingredients that bind water, especially sorbitol and corn syrup/glucose.  He mentions "adding 50% corn syrup to the moisture quantity in ganaches".  Do you agree that the 'moisture quantity' is whatever amount of water is in the cream or purees, so 100 g of 40% fat cream adds 60 g 'moisture' that would be bound by 30 g glucose? 

 

Yes ... but it takes into account the sugar coming from the chocolate.

If you complete the recipe by adding 200 grams of dark chocolate, then 30 grams of glucose will be enough for 100 grams of cream.

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  • 2 weeks later...
Posted (edited)

Would someone be willing to test WC for a "dulce de coconut" ?  I buy sweetened condensed coconut milk and put the can in pressure cooker or boil it, just like with regular condensed milk to make dulce de lece.  Example product I purchase at grocery store here.  I occasionally make little filled chocolates for fun, getting a WC tester is.. overkill.  In this case, I may be shipping the chocolates to a friend in canada, and shipping from California averages 10 days. I did test batch few months ago and left them on counter for a couple weeks, they seemed okay?  I'd rather be safe with science though...

81jpQrQBFFL._SL1500_.jpg

Edited by jedovaty (log)
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1 hour ago, jedovaty said:

Would someone be willing to test WC for a "dulce de coconut" ?  I buy sweetened condensed coconut milk and put the can in pressure cooker or boil it, just like with regular condensed milk to make dulce de lece.  Example product I purchase at grocery store here.  I occasionally make little filled chocolates for fun, getting a WC tester is.. overkill.  In this case, I may be shipping the chocolates to a friend in canada, and shipping from California averages 10 days. I did test batch few months ago and left them on counter for a couple weeks, they seemed okay?  I'd rather be safe with science though...

 

 

Are you using the coconut DDL straight or mixing with chocolate to make a ganache?  I don't think I'd trust it on its own for 2 weeks.  To keep it vegan, Valrhona Amande could be good with that.

 

If you send me samples I can test them, PM me or search for Dolcetta Artisan Sweets for my biz address.

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Thank you!  I use it as a direct filling.  I'm more interested in keeping it dairy free than vegan, one family and a few friends have issues with casein.  Almande looks interesting!  Actually.. easy to make at home, no different from a few things I do with coconuts and hazelnuts!  Thanks for that :)

 

Will be in contact - whole farts carries the product, but they are out of stock in the store near me right now.

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I took a reading on another brand of that (and not vegan) and it was above 0,85, someone measured something else. I bought a new can of the same thing because I forgot to note down.

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