Historical Background - Freeze-drying of Pharmaceuticals and Biopharmaceuticals - page 12

1.5 Stability: The Downside
Usually, and for obvious reasons, stability is discussed in terms of its
benefits. Any such discussion would, however, be incomplete without
some mention of commercial situations where stability is undesirable, or
even dangerous. Enzymes are used in many food manufacturing proc-
esses, mainly in the form of lyases (amylases, phosphorylases, lipases,
etc.). Health and safety considerations demand that they must have been
removed entirely before the finished products reach the marketplace. In
a similar manner, any extraneous enzymes used as processing aids in
protein purification protocols have to be removed prior to freeze-drying.
The situation is even more dangerous for pathogens that can undergo
sporulation during drying, e.g. canned meat products, that contain
minute residual traces of Clostridium botulinum. The spores formed
during processing possess a very high degree of resistance to any
treatments aimed at their destruction. They remain in this dormant
and highly resistant state until their germination to a vegetative state
takes place. The mechanisms of such germination triggers are not yet
well understood, and the incidence of, and fight against, pathogen
stability by sporulation continues to present major challenges to the
food industry.