A method for processing biological material containing stringy tissue in a container having a tissue collector disposed in a tissue retention volume on one side of an internal filter includes washing biological material contained in the tissue retention volume with wash liquid to the tissue retention volume and allowing the wash liquid and rotating the tissue collector disposed in the tissue retention volume relative to the container in a first direction of rotation about an axis of rotation to sweep the teeth positioned on the tissue collector through the biological material and to collect stringy material on the tissue collector.