a method of producing a body portion of a capsule comprises forming the body portion from a polymeric material and subsequently treating one or more piercing zones of the body portion to alter one or more material characteristics of the polymeric material of the piercing zone relative to the material characteristics of the polymeric material of a remainder of the body portion . a capsule for the preparation of a beverage comprises a body portion comprising one or more piercing zones intended to be pierced in use by one or more piercers of a beverage preparation machine to provide one or more inlet apertures for feeding water under pressure into the interior of the capsule . the body portion is formed from a polymeric material . the polymeric material of the piercing zone comprises a transformed structure which has been treated after formation of the body portion to alter one or more of its material characteristics .