Relationship Between the Bostwick Measurement and Fluid Properties

Consistency of tomato concentrates was evaluated in a Bostwick consistometer. The concentrates were produced in a semibatch evaporator at soluble solids content from 5.3 to 24.0°Brix. The apparent viscosity, yield stress and density were measured at 20C. With respect to the gravity current analysis, the Bostwick measurement correlated well with the theoretical ratio of the apparent viscosity to density (R2 = 0.96). For the concentrates with yield stress values in the range of 60–200 Pa, the predicted extent of flow based on the slump analysis was within 2% of the measured extent of flow in the Bostwick consistometer.