Freeze and thaw
are processing steps within the manufacture of biopharmaceutical intermediates and finished products. In a frozen state, biopharmaceutical products are stable over a longer period of time and can be more easily transported and stored 1. Furthermore, the danger of an unwanted reaction or contamination can be minimized in this state 21. The choice of a suitable freezing and storage container is dependent on the properties and quantities of the product. While both plastic tubes (see vials) and bags are used for milliliter-scale applications, only bags are used in liter-scales. Larger quantities between 50 L and 500 L are frozen in transportable stainless steel containers. Bags are recommended for the freezing of biological products in combination with bag handling systems and manifolds.
For a defined process control of freezing and thawing bags, specially designed freeze and thaw systems can be used, such as the Celsius freeze and thaw system (Sartorius Stedim Biotech). A potential disadvantage of using bags for freeze and thaw application is their integrity testing. Damaged bags can often only be detected after thawing if the user does not apply integrity testing systems to bags such as the Sartocheck 4 plus Bag Tester (Sartorius Stedim Biotech).