How long cream ganache remains fresh without deterioration in flavor or the development of bacteria and mold depends on the composition of the ganache itself, proper preparation and finishing techniques, and proper packaging and storage. As a general rule of thumb, cream ganache-filled pralines can be kept at room temperature (68&F/20.0&C) for approximately two weeks.

The shelf life of cream ganache is largely determined by the water activity in the mixture. Water activity measurements (Aw) indicate how much water in a mixture is available as a medium for the growth of bacteria and microorganisms. Water activity is based upon a scale of 0 to 100, and lower water activity measures indicate a longer product shelf life.

A number of ingredients can be added to ganache to lower the water activity and improve shelf life. Sugar is hygroscopic, meaning that it helps retain moisture. Consequently, the addition of various forms of sugar helps lower water activity by binding water to the sugar and preventing it from becoming a breeding ground for bacteria and other hazardous organisms. Sucrose (granulated sugar) is not a good choice, as it crystallizes easily and can alter the texture of ganache. Corn syrup, glucose, and invert sugar all work well to maintain the smooth texture of ganache and increase the product’s shelf life.
Corn syrup and glucose are added to the cream prior to heating to ensure that they fully dissolve and incorporate into the liquid. Invert sugar, however, should not be boiled with the cream, because boiling will cause it to lose its beneficial properties. It can be added later, when the cream is combined with the chocolate. As a general guideline, the amount of sugar added should equal 7 to 10 percent of the total weight of the ganache.
Other additives such as Sorbitol or potassium sorbate can be added at the beginning of the process to act as a preservative for improving the shelf life of cream ganache. Potassium sorbate is a convenient mold and fermentation inhibitor, formulated to help prevent mold growth from within. This water-based preservative is ideal for all candies and pra-lines. As a general guideline, use 0.1 percent of the total weight of the ganache. Adding more than 0.2 percent of the total weight of the ganache will affect the product’s flavor and texture. For Sorbitol, you may add up to 5 to 7 percent of the ganache’s total weight.