Measurement of freezing-point depression of selected food solutions.

Freezing-point depression of selected food solutions were measured at various concentrations in order to reveal the characteristics of solid-liquid phase equilibrium. The measurements were carried out on a hand-made apparatus that was calibrated before the measurement by some selected reagents (acid and sugar) with known thermal properties. The results revealed that the freezing-point depression of selected food solutions deviated from the behaviour of the ideal solution with increasing solute concentration, so the water activity for non-ideal solution was introduced to the freezing point depression equation.