Amylase (clarase)

Amylase (clarase) is supplied as a light coloured powder.  It is a form of α-amylase that acts on starch (amylose and amylopectin) and breaks it down to simple sugars such as maltose and dextrins.  Many organisms, including humans, use amylase to render dietary starch soluble so it can be absorbed during digestion.

Amylase (clarase) contains reducing sugars that are added at the manufacturing stage as an inert diluent to achieve batch-to-batch consistency.  The presence of reducing sugars in the starting materials means it is not reliable to follow the progress of the reaction by testing for the appearance of sugars with Benedict's Solution.  Instead, use the iodine test to show loss of the starch substrate.

Reducing sugars have a carbonyl group (-CO) that can be oxidised in certain conditions.  Examples of reducing sugars include glucose, fructose and maltose.  Note, ordinary cane sugar, sucrose, is not a reducing sugar.

Iodine Test  (MC26.1)

The iodine test is used to detect the presence of starch, specifically amylose.  A solution of iodine in potassium iodide (MC26.1, I/KI, 1.5%/3%) forms an intense blue-black colour when it comes into contact with amylose.

Benedict's Solution  (MC4.1)

Benedict's Solution (MC4.1) is based on copper sulphate, CuSO₄, which is a clear transparent blue colour in solution.  When Benedict's Solution is heated in the presence of a reducing sugar, the sugar is oxidised and the Cu²⁺ is reduced to Cu⁺, forming a characteristic red-orange precipitate of Cu₂O.  A colour change from blue to orange confirms the presence of reducing sugars.

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