Starch to Sugar
In beer brewing, I know that the basic reactions
are: starch --> fermentable sugars & sugar --> alcohol + carbon
dioxide. The balanced chemical equation of sugar to alcohol is
C6H12O6 --> 2(CH3CH2OH) + 2(CO2), however I need to know the
equation of starch to sugar.
Starch is a large molecule that is made of branching chains of glucose
molecules. It doesn't really have a simple chemical formula, like the
ones you list in your question. Cells can break starch down into
glucose by taking the chains apart. This kind of reaction, called
hydrolysis, requires water as one of the reactants.
I recommend looking at any introductory biology textbook for diagrams
that show how glucose molecules can be put together and taken apart.
The web sites below also show molecular diagrams of starch molecules.
Unfortunately, you won't find a simple chemical equation for the
reaction. The starch molecules involved are too big and complex for
natural starch is a polymer of glucose and can be
separated into 2 fractions:one, called amylose forms a
colloidal dispersion in hot water.The other,
amylopectin is completely insoluble. Both forms are
composed only of D-glucose units. Amylose consists of
un unbranched chain of glucose units joined from the
first to the fourth carbons by alpha linkages. There
may be from 60 to 300
glucose units per chain.
Amylo pectin has similar chains, and it also has
branches off the sixth carbon. There may be 300 to
6000 glucose units per amylo pectin molecule.
Commercial starch is a white powder that under
controlled conditions can be partially hydrolized.
Hydrolisis is catalyzed by acids and by enzimes and
leads ultimately to the formation of glucose.
So as you can see the chemical equation, of that
even the over all is too much complicated to be
here in that site.
Thanks for asking NEWTON!
Mabel (Dr. Mabel Rodrigues)
Click here to return to the General Topics Archives
Update: June 2012