Comparative study on the physical characteristics of goat milk pasteurization through serial and circulation systems of ultraviolet method

This research was intended to evaluate the physical characteristics of pasteurized goat milk by serial and circulation systems of ultraviolet (UV) rays. The parameters measured covered viscosity, specific heat, conductivity, pH, water content, freezing point and specific gravity. The UV reactor system consisted of a reactor housing made of ST 316 material equipped with 10W UV lamp, UV-C 253.7 nm and a quartz tube with 1.80 J per square cm or 2314.83 J per liter as a dose per reactor for the serial system and 1.56 J per square cm as a dose for circulation system. The results of the serial system showed that the physical characteristics were not significantly different from the control at 0.5 percent, whilst the circulation system with flow rate of 10 cc per second and dose of 1.56 J per square cm showed that the treatment of two, four and six circulations on viscosity treatment had different effect from the control (P less than 0.01), whereas other treatments did not differ from the control (P more than 0.05).