DNA CLUB

Loyola Institute of Frontier Energy (LIFE) 1

DNA CLUB (Department of Biotechnology Natural Resource Awareness Club)

LAB MANUAL 4

FOOD TEST

Prepared by

Dr. M. Selvanayagam M.Sc., Ph.D., F.A.Z., F.A.E.Z.,

S. Subash Kumar M.Sc., M.Phil., B.Ed.,

Loyola Institute of Frontier Energy (LIFE)

Regional Resource Agency (RRA) for the DNA Club’s of Tamil Nadu

Loyola College, Nungambakkam, Chennai – 600 034

Ph: 91 44 28178332 Email: dnaclub2008@gmail.com

DNA CLUB

Loyola Institute of Frontier Energy (LIFE) 2

FOOD TEST 1.1. TEST FOR CARBOHYDRATE

Moore’s Test

Aim

To determine presence of Glucose in the given sample Materials

Test tube, Test tube holder, Beakers, Spirit lamp and Water bat

Reagents

Glucose solution, 2% NaOH solution

Principle

Carbohydrate react wit NaOH and produces yellow reddish brown color appearance due to the reduction of glucose into caramel. Procedure

1. Take 1ml of given sample solution in a clean test tube 2. Add 1ml of NaOH 3. Keep the test tube in the boiling water bath 4. Appearance of yellow reddish brown color indicates the presence of

carbohydrates (glucose)

Sample 1ml

+ 2% NaOH

1ml

Reddish brown color

Presence of Carbohydrates

Precautions

1. Use clean dry test tubes 2. Keep away form the flame and water bath 3. Use test tube holder in step 3 4. Follow the instruction of the teacher In-charge

Δ

DNA CLUB

Loyola Institute of Frontier Energy (LIFE) 3

1.2. TEST FOR PROTEIN Ninhydrin Test

Aim

To detect the presence of protein in the given sample Materials

Test tube, Test tube holder, Beakers and Spirit lam

Reagents

Food sample and Ninhydrin solution Procedure

1. Take 3ml of sample solution in a clean dry test tube 2. Add 2 to 3 drops of Ninhydrin reagent 3. Mix the solution thoroughly and boil it 4. Cool it down to the room temperature 5. If the sample turns into bluish color it will indicate the presence of protein

Sample 3ml

+ 2 to 3 drops

of Ninhydrin

Bluish color

Presence of Protein

Precautions

1. Use clean dry test tubes 2. Keep away form the flame 3. Use test tube holder in step 3 4. Follow the instruction of the teacher In-charge

Δ

DNA CLUB

Loyola Institute of Frontier Energy (LIFE) 4

1.3. TEST FOR LIPID Saponification Test

Aim

To detect the presence of Lipid in the given sample Materials

Test tube, Test tube holder and Test tube stand

Reagents

Food sample and 5%NaOH Principle

When the lipid mixes with 5%NaOH it turns into soap. It is due to breaking of ester bonds in the lipid molecule by NaOH Procedure

1. Take 2ml of sample solution in test tube 2. Add 2ml of 5%NaOH 3. Appearance of soapy solution indicates the presence of lipid in the given sample

Sample

2ml +

2ml of NaOH

Soapy solution

Presence of Lipid

Precautions

1. Use clean dry test tubes 2. Use test tube holder where ever necessary 3. Follow the instruction of the teacher In-charge