Food test

1. Structure Of Large Molecules & Food Test By Mansi Iyer & Priyal Mehta

2. Structure of large molecules Large molecules are made from smaller basic units. Like simple sugars to starch and glycogen, amino acids to proteins and fatty acids and glycerol to fats and oils.

3. Carbohydrates consist of carbon ( C ), hydrogen ( H ) and oxygen ( O ). They include sugars, starches, cellulose and others. In their basic form, carbohydrates are monosaccharides . These simple sugars can combine with each other to form more complex carbohydrates like disaccharide or Polysaccharide .

4. The building blocks of proteins are amino acids, that consist of a central carbon atom linked to an amino group, a carboxyl group, a hydrogen atom. Within a protein, multiple amino acids are linked together by peptide bonds , thereby forming a long chain.

5. 3 Fatty A cids 1 Glycerol M olecule Fats

6. Triglycerides are the main components of vegetable oils and animal fats. Triglycerides have lower densities than water (they float on water), and at normal room temperatures may be solid or liquid. When solid, they are called "fats" or "butters" and when liquid they are called " oils”

7. What is a food test A food test is a simple test which can easily be performed in the laboratory to identify the main classes of food.

8. Types of Food Test Sugar with Benedict solution Protein with Biuret solution. Starch with Iodine solution Fats with Ethanol

9. Sugars To find if a liquid contains a simple sugar, you will need to do a Benedict’s sugar test Use a test tube. Fill the test tube one-third full of the solution to be tested Add 3-5 drops of Benedict's solution. Properly shake the test tube

10. The result is easy to identify looking at the test tubes…

11. Proteins The Biuret Test is often used to determine the presence of peptide bonds in protein. At this level you will be testing for the presence of protein in foods. What to do- Add 2 cm3 of the liquid food sample to a clean, dry test tube Add 1 cm3 of sodium hydroxide solution and 1% copper (II) sulphate solution. Shake well and allow the mixture to stand for 5 minutes . Observe any color change.

12. The Result Blue = No proteins present Violet = proteins are present Pink = Peptides are present ( Peptides or peptones are short chains of amino acid residues)

13. Starch Procedure: Add a spatula of starch powder Add few drops of Iodine Notice color change

14. The Result If it turns dark blue or black it contains starch…

15. Fats Process: Add the food sample to 2 cm 3 of ethanol, shake well. Allow to settle in a test tube rack for 2 minutes for food to dissolve in ethanol. Empty any clear liquid into a test tube containing 2 cm 3 of distilled H2O. A milky white emulsion is a positive result: lipid is present. If the mixture remains clear, there are no fats present in the sample

16. The result If lipids are present in the mixture, it will precipitates and forms an emulsion.

17. A Resourceful Link http://www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/food_detective/ activity  

18. BIBLIOGRAPHY Available on- http://brilliantbiologystudent.weebly.com/ethanol-emulsion-test-for-lipids.html [on-line] accessed on- 31st October Available on- http://www.biosci.ohiou.edu/introbioslab/Bios170/170_2/biuret.htm [on-line] accessed on- 4th November Available on- http://dev.nsta.org/ssc/pdf/v4-TS_33.pdf [on-line] accessed on- 8th November Available on- http://www.bayerpharma.com/en/research-and-development/technologies/small-and-large-molecules/index.php [on-line] accessed on- 8th November Google images accessed on 12 th November.