| 摘要 |
Thixotropic compositions are concentrated by evaporation of solvent after preliminary treatment of the composition-to-be-concentrated with ultrasonic waves in order to reduce its viscosity. In an example, orange juice concentrate with a soluble solids content of 60 DEG Brix is subjected for 10 minutes to ultrasonic waves at a frequency of 20,000 cycles per second, and is then concentrated under reduced pressure to 63 DEG Brix. The material is then given another 10 minutes of ultrasonic treatment, and further concentrated to 70 DEG Brix. The viscosity of the product is only 150% of that of the original 60 DEG Brix concentrate. The composition to be concentrated may be continuously circulated by a pump through an apparatus comprising an ultrasonic treatment unit, a heater, and an evaporator. |
