Benedict’s reagent test or Benedict’s test is used to testing for simple carbohydrates / reducing sugars/ monosaccharides/ disaccharides.

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2.  A reducing sugar is any sugar that is capable of acting as a
reducing agent because it has a free aldehyde group or a
free ketone group. Reducing sugars react with amino acids
in the Maillard reaction, a series of reactions that occurs
while cooking food at high temperatures and that is
important in determining the flavour of food.
 Not all disaccharides will get positive results with this test.
There are certain limitations for the disaccharides to give
positive results.
 Benedict's reagent test can be used to test for the
presence of glucose in urine, but this test is not
recommended or used for the diagnosis of diabetes
mellitus.
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3.  The principle of Benedict's test is that when
reducing sugars are heated in the presence of an
alkali they get converted to powerful reducing
species known as enediols.
 When Benedict’s reagent solution and reducing
sugars are heated together, the solution changes
its colour to orange-red/ brick red.This colour is
due to the presence of simple carbohydrates. In
specific, the copper (II) ions in Benedict’s
solution are reduced to Copper (I) ions, which
causes the colour change.
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4.  It is an equal-volume mixture of aqueous solution
of Copper Sulfate(CuSO4) and sodium citrate. Here
sodium citrate is the complexing agent. Benedict's
solution is a deep-blue alkaline solution used to test for
the presence of the aldehyde functional group- CHO.
 Formation of red coloured copper(I) oxide indicates the
formation of a precipitate.This precipitate is insoluble in
water. As Benedict’s test continues, the concentration of
reducing sugar increases. Following this condition, high
amount of brick-red colour precipitate will be formed at
the end of the test tube. Sometimes you will find small
amounts of copper oxide along with brick-red precipitate.
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5.  Sodium carbonate of Benedict’s reagent facilitates
the alkaline conditions which are required for the
redox reaction. Another compound Sodium citrate
complexes with the copper (II) ions to avoid
degradation into copper(I) ions during storage.
 Some complex type of carbohydrates like starch or
amylum consisting of a large number of glucose
monomer units joined by glycosidic bonds.Starch or
amylum don’t react or react very poorly with
Benedict's reagent, due to the relatively small number
of reducing sugar units.
 Inositol is another complex carbohydrate which
produces a negative result with Benedict’s test.
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6.  Sucrose which is commonly known as table sugar contains
two reducing sugars moieties fructose and glucose.These
reducing sugar are joined by their glycosidic bond in such a
way as to prevent the glucose isomerising to aldehyde, or
the fructose to alpha-hydroxy-ketone form. Sucrose is
thus a non-reducing sugar which does not react with
Benedict's reagent.
 Sucrose still indirectly can produce a positive result with
Benedict's reagent if heated with dilute hydrochloric
acid(HCl) prior to the test.The acidic conditions and heat
break the glycosidic bond in sucrose through hydrolysis
process.The products of hydrolysis process are reducing
sugars (glucose and fructose) which can be detected by
Benedict's reagent.
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