Promoting the purchase of, and visually verifying the authenticity of a mixed purchased beverage

In a beverage supply system of the type which includes a mixer having a mixing chamber for holding a drink mixture comprising at least a first and a second ingredient, said first ingredient being prominent and of interest and importance to customers for such beverages, said mixer receiving from a first source a supply of said first ingredient, and from a second source a supply of said second ingredient, and a release valve on said mixing chamber for releasing a beverage to be consumed by a customer, the improvement comprising:

• said first source exposed to the view of a prospective customer;
• an indicator associated with said first source adapted and so disposed and arranged as to provide a visible signal that first ingredient is being withdrawn from said first source while this event is occurring;
• a control circuit responsive to withdrawal of beverage from the mixer whereby, substantially contemporaneously while beverage is withdrawn, the circuit will energize the indicator.