In this paper the design and implementation of a novel Differential Photoacoustic Cell (DPC) system is presented. The system was used to study the thermo optic transition in water-starch suspension called gelatinization. The melting temperature of Gallium was used to calibrate the temperature of the system. Both temperature values for starch gelatinization and gallium melting were agreed with those obtained using differential scanning calorimetry (DSC). The results show that this system is suitable to study other thermal processes in food or any thermal transition at low temperature.