food science

 
 

  • PREPERATION OF FEHALING SOLUTION

   Prepare by mixing equal volume of solution A and solution B immediately before use. 

    • PREPERATION OF SOLUTION A

    Dissolve 34.639gm of copper sulfate crystals in water and add 1ml of concentrated sulfuric acid dilute to 500ml and filtered.

    •  PREPERATION OF SOLUTION B

    Dissolve 173gm of potassium sodium tartrate and 15gm of NaOH with water and diluted to 500ml let the solution stand for 1 day and filtered.

 

  • STANDADISATION OF FEGHALING’S SOLUTION

   Weigh out accurately about 1gm of dextrose and dissolve it in water and make up the solution to 500ml with distilled water.

   Pipette out each of using separate pipette solution A and solution B in to a 250ml conical flask and about 23ml of dextrose solution from a burette add few pumices and dilute with water heat to boiling over a flame and add 1ml of methylene blue indicator solution and while keeping the solution boiling complete the titration with in 3 minutes end point is indicated by the change of color from blue to red.

    CALCULATION

                         

Normality of Fehling’s solution         = W*V
                                                                500

Where

             W= weight of dextrose taken.
             V = volume of dextrose solution required.

  • PREPERATION OF METHYLENE BLUE INDICATOR

  Dissolve 0.2gm methylene blue in 100ml distilled water.

  • PREPERATION OF IODINE SOLUTION

                                                       Equivalent weight of iodine = 127

 Weight of iodine required to prepare 0.05N 500ml solution = 127*500*0.05                                                                                                                 1000
                                                                                                        = 3.175

  Weigh out accurately about 3.175 gm of iodine crystals and double the weight of iodine crystal 6.35gm of KI. Little by little both are powdered with small quantities of water and dilute to 500ml.

  Standardize the iodine solution by using 0.05N sodium thiosulphate.

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