Fiehe’s test to detect adulteration in Honey.

To Detect adulteration of honey, fiehe’s and analine chloride are the initial test which is caried out in the laboratory.

What is fieh’s test?

This honey test help Identify:
– Honey adulteration with commercial or invert sugars
– Overheating or aged honey

What does fiehe’s analyze in honey?

This test helps identify the amount of HMF (Hydroxymethyle furfural) in honey.

What is Hydroxymethyle furfural?

HMF is a decay (acid catalysed) product of natural fructose present in honey. Fresh natural honey has around 10-14 mg/kg of HMF whereas Old honey has a higher value.

How can fiehe’s test identify purity of honey?

Invert sugar and jaggery has a very high level of HMF content. A positive result indicates the presence of a high level of HMF.

Can Positive “Fiehe’s test result” confirms honey adulteration?

No, because even pure honey could have a higher level of HMF in the following situations.
– If honey is stored for a longer period of time
– when honey is stored in a hot atmosphere
– If honey is heated during processing

Can negative “Fiehe’s test result” cofirms purity of honey?

No, because recent honey adulterants(fake honey) like HFCS and rice syrup has “Nil” HMF.

The procedure of Fiehe’s Test:

The time needed: 15 minutes.

Supply:

Solvent ether, Resorcinol crystals, Hydrochloric acid

Tools: 

Mortar, pestle, test tube, Petri dish

Procedure:

Fiehe’s test can detect adulteration of honey with invert sugar (Acid hydrolyzed sugar). It actually detects the presence of HMF (Hydroxymethyl furfural) content in honey. Invert sugar has high HMF content whereas, honey has lesser HMF content (around 10 mg/kg).
Some times even genuine honey has higher HMF when Honey is heated or stored for a long time.

  • Step 1

    Take 5ml of honey in a small mortar. Add 10ml of solvent ether. Mix the solution well using a pestle.                             

    mortar pestle
  • Step 2

    Take a Petri dish and add the supernatant solution from the mortar. Allow it to dry in the open air.

  • Step 3

    Take 5ml HCL (Hydrochloric acid) ina test tube. add 1 g of resorcinol crystals. shake it well to dissolve.

    Fieh's test
  • Step 4

    Add a few drops of resorcinol HCl solution in the petri dish (This should be done once the ether dries out completely)

  • Step 5

    Observe the colour in the petri dish.

Inference:

Positive result: Pink or cherry red colour indicates the presence of high HMF. This means honey has either invert sugar adulteration.

Negative result: There is no change in colour to a yellowish pink colour. Negative Result indicates No adulteration of common or Invert sugar.

Fssai Parameter for fiehe’s test :

Fiehe’s test should be negative

If Fiehe’s test is positive, and hydroxymethylfurfural (HMF) content is more than 80
milligram/kilogram, then fructose: glucose ratio should be 1.0 or more.

Conclusion: 

This test can detect only Invert sugar adulteration in honey. Other newer adulterants need higher tests.

Aniline Chloride test: 

The procedure of Aniline Chloride Test:

Dissolve 3g aniline crystals in 10ml concentrated HCl. This reaction produces Aniline chloride. 

Take a few drops of honey in a Petri dish, add 2-3 drops of aniline chloride solution. 

Result: If the solution turns to orange colour, It indicates the presence of invert sugar. 

No colour change result indicates pure honey.

Reliability: This test can only identify common sugar or invert sugar adulterations in honey. Latest adulterants may skip this test. 

Iodine test:(For the presence of starch)

The procedure of Iodine test: Take 5ml of honey and 5ml of water, make it homogenise by mixing it well.

Prepare an Iodine solution by Adding 3g of potassium and 1g of Iodine in 50ml of water.

Add Iodine solution to the honey-water mixture. 

Result: If the solution turns to purple or red colour it indicates the presence of starch in honey. 

No colour change indicates pure honey. 

Reliability: This test is only for the presence of starch. Not for other adulterants. 

Conclusion:

These tests can identify the adulteration of honey with Invert sugar, for other adulterants like HFCS & Rice syrup there are higher tests. Get the complete list at our blog post types of honey adulterations.

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