Image Number 6 for United States Patent #6090972.
Disclosed is a method of cooling and crystallizing .alpha.-L-aspartyl-L-phenylalanine methyl ester, which is a sweetening agent, commonly referred to as aspartame. An aspartame solution is cooled such that the solution is flown while being continuously in thermal contact with a coolant. As the cooling of the aspartame solution by the thermal contact with the coolant proceeds, the temperature difference between the aspartame solution and the coolant remains substantially constant. The coolant flows in the opposite direction as the aspartame solution flows and cools an upstream part of the aspartame solution as the coolant flows downstream.