In a milking machine teat cup wherein an animal to be milked has its teat
inserted into a teat cup liner during milking, a first electrode extends
about or within at least a portion of the teat cup liner. To clean and/or
disinfect the liner, a second electrode is inserted into the liner and
the two electrodes are charged so as to generate plasma in any free space
between the inserted second electrode and the interior surface of the
liner. The generated plasma species destroy organisms that cause
mastitis, and can additionally kill other unwanted organisms and/or
perform cleaning of the liner's interior.