FIELD: sugar industry. SUBSTANCE: method involves high-frequency measuring of total tangent of angle of massecuite losses at ac frequency of 8-27 MHz and simultaneously measuring effective massecuite viscosity; estimating parts per weight of crystals from design formula, with measured values being taken into account. Method allows content of crystals in massecuite to be controlled in the process of obtaining crystalline product in vacuum units. EFFECT: increased precision in determining parts per weight of crystals in massecuite and increased efficiency. 1 ex, 1 tbl
