n. — Food, somewhat rare
the finest category of granulated sugar (see Image 1).
Type: 2. Preservation — Berry sugar is also called superfine granulated sugar, castor or caster sugar, fruit sugar or bar sugar (see the Canadian Sugar Institute reference).
The earliest attestation of berry sugar in Canada is from an English cookbook (see the 1910 quotation), which solidifies its classification as a preservation from BrE.
The term is most often used in the UK (see Chart 1), but has considerable frequency in Canada in relation to other non-UK locations (see Chart 2).
See also COD-2, s.v. "berry sugar", which is marked as "Cdn.".
See also: butter tart icing sugar confectioners sugar
- The name might originate from its use to sweeten berries, because it dissolves quickly, avoiding a "crunchy" sensation.
- 1910  Recipe for Bath buns from a good English cookbook [. . . ] one cup of berry sugar [. . . ] 
- 1930   Pure Alberta Sugar Available in the following sizes.
Granulated 100s, 50s, 20s, 10s, 5s. Icing 100s, 25s, 2s, 1s. Bar or Berry Sugar 100s, 25s. [Advertisement] 
- 1949  If more sugar is needed add berry sugar and stir well. 
- 1952  English New Year's Fruit Cake [ . . . ] 13 oz. (1 5/8 cups) flour, 1 tsp. salt, 1/2 cup berry sugar (a finer sugar than granulated, but not as fine as confectionery) 
- 1962   Peach Chiffon Pie [. . . ] 1/2 cup fruit or berry sugar 
- 1989  Superfine (berry) sugar or confectioner's sugar dissolve more easily than table sugar. Poorly dissolved sugar leads to gritty texture and tiny drops of amber syrup collecting on the surface after baking. 
- 1991  I find that the texture is more delicate when the dough is mixed with the fingers rather than in a machine. For either method, use superfine sugar (berry sugar) for the best texture and be sure to soften the butter. 
- 1994  Sweetenings: Substitute soft brown sugar (Demerara suggested) or castor (berry) sugar; add treacle OR orange marmalade; crystalized ginger. 
- 2011  Mix 1.25 shots tequila of your choice (I use blanco), 0.75 shot of Cointreau, a shot of fresh lime juice, half a shot of fresh lemon juice, and a teaspoon of berry sugar. Stir with ice cubes.