Final answer:
The sugar stage used for fondant, mousseline buttercream, Italian meringues, and fudge is typically the soft-ball stage, with variations depending on the specific recipe and environmental conditions.
Step-by-step explanation:
The sugar stage used for Fondant, mousse line buttercream, Italian meringues, and fudge typically relates to the temperature to which the sugar syrup is cooked, as this affects the concentration of the sugar and thereby the consistency of the final product. For fondant, the sugar syrup is cooked to the soft-ball stage, which is between 235°F to 240°F (112°C to 116°C). At this stage, when the sugar syrup is dropped into cold water, it forms a soft, flexible ball that flattens when removed.
Italian meringues require a sugar syrup cooked to the soft-ball stage as well, which is then gradually beaten into egg whites to create a glossy and stable mixture. Fudge also utilizes the soft-ball stage but sometimes cooked slightly higher to ensure it sets firmly. In some recipes, cooking until it reaches the soft-ball stage suffices to achieve the creamy texture desired. It is important to note that the desired sugar stage can vary depending on the specific recipe and the environmental conditions, as humidity can affect sugar syrups.