What is the best way to inactivate the enzymes when a digestion is complete?

There are two components to inactivation of the digestive enzymes commonly used for tissue dissociation.  To inactivate protease activity, a serum-containing media or buffer is most effective.  Buffers or media containing human serum albumin (HSA) are ineffective in suppressing protease activity, even at very high concentrations of protein (>10%). However, serum-containing buffers do not inhibit collagenase activity.  The most effective method for inactivating collagenase activity is reducing temperature. Collagenases will lose about 80% their maximal activity at 26°C. Thus, introduction of an ice-cold, serum- containing media should virtually eliminate all collagenolytic and proteolytic activity of an enzyme mixture.