Abstract: A deformable support for a pressure plate blood processing centrifuge apparatus is described. A plate 50 is disposed adjacent a deformable support 10 having a recess for a flexible bag 8 in which blood is processed. Under the influence of centrifugal force the plate 50, which is disposed inwardly nearer the center of rotation than the bag 8, exerts a force against the support 10 and bag 8 and expels a separated blood component from the bag into a receiver container 6.The support 10 absorbs forces in the bag 8 thereby enabling the bag to be made of thin walled inexpensive material which would otherwise rupture under the separation forces. Yet the support 10 is sufficiently yielding to enable the pressure plate 50 to move and create an expelling force.