Water activity for chocolatiers

Chocolate water activity — estimate aw from your ganache recipe

Water activity (aw) is the single most important number for ganache shelf life. The ChocoX Shelf-Life Predictor estimates it from your recipe in seconds — no laboratory equipment required.

What is water activity?

The number that governs whether your ganache lasts a week or six weeks

Water activity (aw) measures how much of the water in a food is available to support microbial growth. It runs from 0 (completely dry) to 1.0 (pure water). A ganache with an aw of 0.70 will keep for several weeks at room temperature. The same recipe with an aw of 0.85 may be safe for only a week or two.

This is why moisture content alone tells you very little. Two recipes at 18% water by weight could have completely different water activities depending on how much sugar, glucose syrup and fat they contain — because those ingredients bind the water and make it unavailable to bacteria and moulds.

The Shelf-Life Predictor showing which ingredients raised or lowered the water activity of a ganache recipe

How the Predictor works

Recipe in, aw estimate out

The ChocoX Shelf-Life Predictor is a Windows desktop program. Enter each ingredient and its weight in grams. It recognises what each ingredient is, estimates the water activity and gives you a shelf-life category with a cautious worst-case margin.

  • Estimated water activity and worst-case aw
  • Shelf-life category (short / medium / long)
  • Which ingredients raised or lowered the risk
  • Confidence rating and guidance on when to lab-test
  • Explore tab: change ingredient amounts, see revised aw instantly

Ingredients and aw

What moves water activity in a ganache?

The main levers are:

Raises aw Cream, milk, fruit purées, water-based flavourings. More of these = higher aw = shorter shelf life.
Lowers aw Invert sugar, glucose syrup, sucrose, chocolate solids, fat. More of these = lower aw = longer shelf life.
Also affects aw Alcohol reduces aw and has direct antimicrobial properties. Cocoa percentage matters — darker chocolate lowers aw more.

Estimate your ganache water activity in seconds

Buy the ChocoX Shelf-Life Predictor once for £25. Enter any ganache recipe and see a water activity estimate, shelf-life category and plain-English explanation — no lab or aw meter needed.