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the other day a member asked about the difference between "xanthan gum and
guar gum.  also the difference between potato starch and potato starch flour.
this explanation was taken from a news letter from "Dietary Specialties"
dated autumn 1996 Xanthan gum is a powder milled from the dried cell coat of
a microorganism called campestis,grown under laboratory conditions from the
fermentation of corn sugar.  it is used in foods as a thickener,emulsifier
(to improve homogeneity, consistancy, stability or texture), and stabilizer
(to impart body,improve consistancy,texture, or "mouth feel").  Guar gum is a
powder derived from the seed of the plant Cyamopsis tetragonolobus, a member
of the legume family.  Guar gum is used as thickener and stabilizer in foods.
Guar gum has a high fiber content which used in large amounts may produce a
laxitive effect, particularly in those with sensitive digestive systems.
using these products is interchangeably is not recomended.

Is there a difference between potato starch & potato starch flour?  the
answer according to the news letter is:  potato starch and potato starch
flour are the same ingredient.  this is a very fine white product with a
bland taste.  it is used in combination with other gluten-free flours in
baking, and can be used alone as a gluten-free thickening agent for cream
soups.  Please do not confuse potato starch with potato flour.  potato
flour is a heavy flour with a definite potato taste.  when potato flour is an
ingredient in a recipe, instant potato flakes may be substituted.

as stated above this is from a news letter from a company that deals with
foods for celiac people.I do not understand a lot of the terms stated,however
if it helps good.

alex