Question

Which sugar is called invert sugar? Why is it called so?

Answer 1

Sucrose is dextrorotatory but sucrose on hydrolysis gives dextrorotatory glucose and laevorotatory fructose. On hydrolysis with dilute acids or enzyme invertase, cane sugar gives the equimolar mixture of D-(+)-glucose and D-(-)-fructose. Hence, the mixture becomes laevorotatory.
This sugar which on hydrolysis changes its sign of rotation from dextro to laevo is known as invert sugar.