Each unit of whole blood is broken down into various parts. For up to 42 days, red blood cells can be kept in the fridge. It is possible to keep platelets for a maximum of five to seven days in room temperature storage. For up to a year, fresh frozen plasma is retained in a stored frozen form. The platelets in a unit of blood are taken out and used for the patient first. The red blood cells are kept frozen in liquid nitrogen and can be used later if needed.