Milking clusters for a miling installation have four teat cups, each teat cup having a cup housing and a teat cup liner with a top region and a suction region. A connection for a milk tube is arranged at the cup bottom or at the end of the suction region of the teat cup liner. A mouth portion of a sterile air pressure line is arranged in the top region of the teat cup liner, through which pressure line sterile air is introduced at a volumetric flow rate greater than a fluid aspiration volumetric flow rate at the milk tube, such that a sterile air blanket is established in the top region of the teat cup liner. The milking clusters with the cup liner and sterile air blanket prevent milked milk from being contaminated by contaminants and microorganisms from the shed air, extending storage life for untreated raw milk.