one cup icing sugar

Icing sugar, also known as powdered sugar, confectioners' sugar, or icing powder, is finely ground granulated white sugar blended with a small amount of cornstarch (typically 3-5%) to prevent caking and moisture absorption. The ingredient originates from standard cane or beet sugar that has been processed through multiple grinding stages to achieve an extremely fine, powder-like consistency with particles measuring approximately 10 micrometers in diameter. The cornstarch addition imparts a silky texture and extends shelf stability. The flavor is pure sucrose sweetness with no discernible notes beyond sugar itself.

Icing sugar is distinguishable from regular granulated sugar by its texture and mixing properties—it dissolves instantly in liquids and incorporates seamlessly into batters and glazes without grittiness. Quality varies by manufacturer; premium versions use finer grinding techniques and higher cornstarch ratios for superior sifting and dispersal characteristics.

Icing sugar is essential in confectionery and pastry work, primarily for creating glazes, frostings, buttercreams, and royal icing. It is used to dust finished baked goods, custards, and desserts for visual presentation and added sweetness. In French pâtisserie, it forms the foundation of fondant and marzipan work. The ingredient dissolves readily into fillings, whipped toppings, and meringues, eliminating the granular texture characteristic of larger-crystal sugars. It is particularly valuable in uncooked applications such as icing sugar syrups for decorative work and powdered sugar dredging for pastries and petit fours.

Icing sugar performs best when sifted before use, particularly in delicate applications where lump-free texture is critical. It should be stored in an airtight container to prevent moisture absorption and clumping.