Test for Reducing sugars
Reduction is a chemical reaction involving the gaining of electrons. A reducing sugar therefore can donate electrons to another chemical, in this case benedicts reagent.
- Add food sample you want to test in a liquified form into a test tube
- add an equal volume of Benedicts reagent
- heat the mixture
- if solution is orange/brown reducing sugar is present.
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Test for non reducing sugars
- put sample of food in liquid form into a test tube
- add benedicts reagent
- heat test tube
- if solution remains blue reducing sugar IS NOT present
- add another sample of the food into a new test tube
- and add acid ( hydrochloric acid) as it will hydrolyse any disaccharide present
- then add an alkaline ( hydrogencarbonate solution) to nuetralise acid( benedicts reagent doesnt work under acidic conditions)
- retest the solution by heating with benedicts reagent
- if non reducing sugar is presnt solution will turn orange/brown due to reducing sugars that were produced from the hydrolysis for the non reducing sugar.
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Test for starch
- place sample being tested in a test tube
- add two drops of iodine solution and shake or stir
- presence of starch is indicated by blue black colouration.
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