Expert: Walter Hintz - 5/28/2008

Question
QUESTION: A teacher asked us how to explain how does a spiral honey glazed ham stays preserved. It has to do with the issue of Microbiology. He wants to know if it is Isotonic, Hypertonic, or Hypotonic. I do not understand the concept. Would you please give me and idea so i can research.

ANSWER: The tonicity has to do with the cellular water content in relation to the extracellular water content.  Assume that cellular water would have ratio of water to sugars or salts of 90/10 and the extracellular ratio is the same.  Then the solutions are isotonic.  Now assume that the internal content has a ratio of 90/10 but the external ratio is 80/20 then the cells are in a hypertonic solution and water leaves the cell by osmosis.  Now change the external ratio to 95/5 and the solution is hypotonic and water enters the cell.
  Ham has a high salt content and the water in it is hypotonic.  When a bacterial cell (which would cause spoilage falls on the ham water leaves the bacteria and dehydrates it.  This is the idea behind preserving foods in salt

---------- FOLLOW-UP ----------

QUESTION: What would the cell membrane look like.

Answer
The structure of the cell membrane is difficult to see but it thought to have bilevel plasma like structure made up of proteins, lipids and carbohydrates.  Water passes through it by simple diffusion.  It is differentially permeable controlling what  can pass through