Honey is a natural sweetener derived from bees.Its primary constituents are various types of sugars, especially monosaccharides like fructose and glucose, which contribute to its sweetness, viscosity, and nutritional value. The sugar composition of honey is a quality parameter which enhances not only its taste and physical properties but also its authenticity and commercial value. Testing the sugar content helps in detecting adulteration, ensuring compliance with food standards. This experiment aims to qualitatively and/or quantitatively analyze the sugar content in a honey sample using standard chemical tests and analytical technique.
The commonly used qualitative and quantitative method for sugar testing is using Fehling’s test (for reducing sugars). Here we will discuss about Fehling’s test process in our lab.
Chemical used and their working principle for Testing of Sugar as Reducing Sugar in Honey
- Copper sulphate solution ( Solution A)-34.639 gm of copper sulphate crystals is dissolved in 500 ml of water, then filtered using filter paper. It is used as oxidizing agent as it is the source of copper ion in the testing.
- Potassium Sodium Tartrate(Solution B)-173 g of potassium sodium tartrate and 50 g of sodium hydroxide is dissolved in 500 ml distilled water and allow to rest for overnight.It takes part in the reaction to maintain the pH of the solution so that the whole reaction can run smoothly.
- Sucrose/ Invert sugar solution– This works as standard solution to check the efficiency of the solution A & B.
- Hydrochloric acid– It is used to hydrolyze (breakdown) the non- reducing sugar.
- Sodium carbonate– It is used to neutralize (pH-7) the solution.
- Methylene blue indicator– It is used as indicator as it color change shows the reducing condition during the reaction.
Equipments & Instruments used during the test of Sugar as Reducing Sugar in Honey
- Burret– It used to hold the sample solution during titration. Here we are using 50 ml burette.
- Pipette– Desire volume is pumped by the pipette.Here we are using 5 ml pipette.
- Volumetric Flask- It is used to hold the exact volume of liquid precisely.Here we are using 250 ml Volumetric Flask.
- Conical Flask– It is used to hold Solution A&B during titration.Here we are using 100 ml Conical Flask.
- Bunsen Burner- It provided constant flame during titration.
- Hot Plate – It is used to warm solutions.
- Watch Glass– To cover the beaker mouth.
- Beaker- To hold the solution during warm. Here we are using 250 ml Beaker.
- pH Meter-To check whether the pH is neutral or not .
- Weigh Balance– To measure the sample weight.
Procedure followed to test Sugar as Reducing Sugar
| Step-1 | The invert sugar/sucrose is weighed (0.4750gm approx) and taken in a beaker dissolved in distilled water 1 ml HCL ( used to breakdown the non- reducing sugar) is added and boiled gently and kept aside for overnight. |
| Step-2 | Approximately 1 gm honey sample is taken in 250ml volumetric flask and and volume make up to the mark with distilled water. |
| Step-3 | After 24 hrs maintain pH-7 of invert sugar with sodium carbonate as the medium is acidic & volume make up to 250ml. |
| Step-4 | Freshly prepared 5 ml each solution A & B is taken in a conical flask and first titrate against the standard invert sugar sample with constant flame of bunsen burner using methylene blue indicator. |
| Step-5 | Same as take prepared 5 ml each solution A & B is taken in a conical flask and titrate against the sample with constant flame of bunsen burner using methylene blue indicator.The end point for the titration is indicated the colour change from blue to brick red. |
| step-6 | Stop the heat and note the reading. |
| Step-7 | Calculate according to the formula. |
Calculation for Sugar as Reducing Sugar –
Fehlings Factor(FF) =( Burette reading of standard × standard sample quantity taken )/ volume make up
Reducing sugar(%)= (FF×volume make up to × percentage%)/(burette reading of sample × sample weight)
Points to remember during the testing of Sugar as Reducing Sugar
- Sucrose is a non-reducing sugar so it has to be hydrolyzed with acid and low heat otherwise it will give wrong FF.
- HCL has to be added for proper breakdown from non-reducing to reducing sugar of sucrose.
- The sucrose should be neutralized before starting the test if not the test will give false end point colour.
- Proper heating is compulsory otherwise it will give incomplete reaction.
- Always use freshly prepared Fehling’s solution (A&B) while doing the test.
- Colour changed should be observed properly otherwise it can show wrong result.
- Volume make up is important factor as deviation can change sample concentration.
Importance of Sugar as Reducing Sugar Testing in Honey Sample –
Honey is composed of glucose and fructose which are reducing sugar. By this method we can –
- Confirm the presence of reducing sugar
- Understand the purity or adulteration presence. If the result is extremely high it can contaminated with other highly sweetening agent like cane sugar or Refined sugar and others.
- Estimate overall sugar content
- Reducing Sugar testing ensures honey meets regulatory standards, such as FSSAI, which recommend minimum requirement of Sugar as Total Reducing Sugar in Honey Sample is 65% & IS recommend minimum requirement of Sugar as Total Reducing Sugar in Honey Sample is 70% but we Pro Research & Testing Laboratory recommend minimum requirement for Sugar as Total Reducing Sugar in Honey is 65% – 70%.
Conclusion of Sugar as Reducing Sugar Test
Fehling’s test of honey indicates the natural reducing sugar presence as it is the method which is simple, quick and reliable to detect. We can determine the qualitative and quantitative value of reducing sugar by this method. The positive result that shows the red colour as end point of the method. This should repeat for minimum of 5 times to get the accurate result. The points mentioned above has to be remember during the test. The process should be followed as mentioned accordingly. By following these method, you can easily test the Sugar as Total Reducing Sugar content at any laboratory or manufacturing industry with availability of the equipments & chemicals. If you can’t understand the procedure you can check our real time photo attached with this writing or also you can reach to Pro Research & Testing Laboratory for the testing purposes.
FAQs about Testing in Sugar as Reducing Sugar for Honey Sample:
1.Which method is followed for sugar testing in honey?
Ans- Fehling’s method as it is simple, quick and reliable to detect.
2. How do you understand that your honey is adulterated by other sugar substances?
Ans- By Fehling’s method, if the result is extreme high than the recommended value, it can be easily understood.
3. If the reducing sugar value is very less than the recommended value what can I conclude?
Ans- If the result is extreme low than the recommended value, we can conclude that quality of the honey is not upto the mark.
4. Why standard invert sugar is kept overnight?
Ans- For complete breakdown of sucrose.
5. Why we choose fehling’s method?
Ans- It is the method which is simple, quick and reliable to detect the reducing sugar.
6. What if we do not neutralize the sucrose?
Ans- It will give false end point which cannot be acceptable and show wrong result.
7. What should the end point of the titration?
Ans- The end point for the titration is indicated the colour change from blue to brick red.
8. What is the requirement of Total Reducing Sugar in Honey Sample?
Ans- We Pro Research & Testing Laboratory recommend minimum requirement for Sugar as Total Reducing Sugar in Honey is 65% – 70%.
9. Can I do this test of any Sugar contained sample by this method in any laboratory or manufacturing units?
Ans- Yes,with availability of the equipments & chemicals you can test any product like Cake,Biscuits,Sweet products, Jam & Juices Jaggery etc.. Also you can reach to Pro Research & Testing Laboratory for the testing purposes.
How We Verified This Testing/Research Procedure :
This testing procedure is done under qualified analyst .Continually monitored by expertise.Repeatedly testing is always done to get accurate result.
Written by
Riya Ghosh (M.Sc. Food Technology, MAKAUT)
Designation – Chemist
Reviewed by
Anwesha Das (M.Sc Microbiology,BU)
Designation – Microbiologist
Verified By
Dr. Jyotirmoy Kumar Dey (Phd,Chemistry)
Designation – Senior/Chief Chemist
Experience – 25 Years +