Abstract: An mixing assembly which transfers a number of nutritional fluids from individual source containers into a collection container while noninvasively sensing the type of fluid being transferred is provided. The mixing assembly utilizes a transfer set to establish fluid communication between the source containers and the collection container. A sensing assembly is configured to noninvasively sense a number of the types of fluid flowing through the transfer set to help to prevent improper mixing. For other fluids for which the sensing assembly alone may not be able to distinguish with the desired accuracy, the mixing device utilizes a method to approximate the flow rate of that fluid with the flow rate also providing an indication of that type of fluid. By combining the output of the sensing assembly with the flow rate determination, additional fluids can be identified.