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Just for the record (and to correct a mistake inspired by the Ener-G
spokesperson).
 
Methyl cellulose is not a petroleum derivative. It is formed from
cellulose which is a glucose polymer derived from the cell walls of plants.
It is formed by reaction of the cellulose with methanol to produce methyl
ether groupings at the primary (C-6) and secondary (C-2 and C-3) alcohol
groups of the glucose units in the cellulose chain. The grade used
pharmaceuticaly has 2-3 (average) ether groups per glucose unit.
 
(Apologies for the technicality of the reply - a colleague prepared it
for me and I felt obliged to send it as written.)
 
It is used like xanthan gum though.
 
Paul Shattock