A beverage dispenser provides numerous inventive features in its refrigeration system, diluent delivery system, concentrate delivery system, mixing and dispensing system, and control system. The refrigeration system employs a plate heat exchanger to provide on demand refrigeration of an intermittent water flow. The diluent delivery system includes a flowmeter/solenoid/check-valve assembly. The concentrate delivery system employs a positive displacement pump. The mixing and dispensing system includes a mixing nozzle that has a locking feature such that an elevated blocking surface directly faces the inlet of pressurized diluent to create turbulence. The control system receives package-specific information from a scanner and diluent flow rate information from the flowmeter, and then determines the pump speed in order to set a desired mix ratio.