Ratio of glucose or sorbitol to water ingredients to control water activity

[Stan Kitson]

Are there any ratios, or general rules of thumb, to using glucose (or other water binding ingredients) to water containing ingredients like cream, butter of soy milk?

For example, if a recipe for chocolate ganache has 12% heavy cream (40% fat) and 2% butter (80% fat), the recipe should have between X and Y% of glucose to control water activity. 

[Kerry Beal]

Glucose is typically added as 50% of free water. So if you have 100 grams of 35% cream - that's 65 grams of water so 32.5 grams of glucose. 

 

Invert more like 10%. 

 

Do you have a copy of Wybauw?

 

Glucose actually doesn't have much of an effect on water activity - more of an effect on texture.

[Stan Kitson]

I do have Wybauw, but I had a difficulty understanding his explanation.

He mentioned 50% glucose, 10% Sorbitol, 10% glycerine but didn't mention invert as a water-binder.

 

You made it easier Kerry, thanks.

[Stan Kitson]

The invert binds water, how does that affect the water needed to create the emulsion?

[Kerry Beal]

It doesn't interfere in that process.

[paulraphael]

It's the fructose in the invert. Glucose binds a little water, fructose binds a lot. I suspect fructose isn't used more in kitchens because it's expensive.