Sucrose is dextrorotatory: [alpha] = +66.5 degrees.

On hydrolysis $\frac{acid or enzyme invertase}{sucrase}$: Sucrose → Glucose ([alpha] = +52.7 degrees) + Fructose ([alpha] = -92.4 degrees)

Net rotation of equimolar mixture = $\frac{+52.7 - 92.4}{2}$ = -19.85 degrees (levorotatory).

The sign of rotation "inverts" from (+) to (-), so the hydrolysis product is called "invert sugar." This is used in confectionery (honey naturally contains invert sugar — bees produce invertase).

This concept demonstrates that optical rotation depends on the specific molecule, not on whether it's a "sugar." Fructose is actually the most levorotatory common sugar despite being called a sugar (often confused with "sweet = dextro").