BLOG 1: FOOD TEST ( PRACTICALS 6th & 7th period )

GOOD MORNING BOYS .
KINDLY MARK YOUR ATTENDANCE FIRST.


Today we will achieve the following LEARNING OUTCOMES :-
Students will be able to IDENTIFY & TEST the presence of Sugars , Starch , Proteins , Fats in various food samples provided to them .


GENERAL INSTRUCTIONS:

1. Write the Experiment in your Practical File .
2. There is one YouTube video link provided to you here on the blog . Kindly watch it before reading the notes.

3. Since some of you got a wrong BIOLOGY LAB MANUAL from stationary so I am sending you the write up for the same . If you have LAB MANUAL OF CLASS 11 , then kindly tell me I will make you mark the pages from it to write.

4. YOU CAN  WRITE THE EXPERIMENT AFTER THEORY  IN TABULATED FOR . 
DIVIDE THE RULED SIDE IN TO 3 COLUMNS 

EXPERIMENT |  OBSERVATION | INFERENCE 


Let's BEGIN ....

WATCH THE VIDEO LINK GIVEN BELOW  :


https://youtu.be/QacQmS3aaTI

Aim

To carry out appropriate tests to detect the presence of sugar(sucrose), starch, proteins, and fats in suitable animal and plant materials.

Theory

Nutrition is a source through which living entities obtain food for the body to get fueled with energy. Therefore the food we eat must be well-balanced with all the substances that are required by our body to perform daily activities, these substances are known as nutrients.

Nutrients nourish the body by releasing the energy required for the body’s growth. Some of the nutrients found in food are:

• Proteins
• Carbohydrates
• Fats
• Vitamins
• Minerals
• Dietary fibers

What are proteins?

They are body-building nutrients which aid in the repair of damaged body parts and also in the growth of the body

What are vitamins and minerals?

These nutrients are reflected to be protective food. They protect us from diseases by providing resistance against germs that are known to cause diseases.

What are carbohydrates?

Carbohydrates are nutrients that provide energy to the body instantly. Fats are also energy-giving foods and store energy.

Carbohydrates contain starch, sugars, and fibers which consists of sugar molecules containing hydrogen, carbon, and oxygen. Carbohydrates can be categorized into:

• Simple carbohydrates – They are composed of 1 or 2 units of sugar hence can be broken down and be absorbed easily. Simple carbohydrates are subdivided into:
• Monosaccharides – Composed of one sugar unit
• Disaccharides – Consists of 2 chemically-associated monosaccharide units. Example – Sucrose, Maltose, Lactose
• Complex carbohydrates – Consists of long chains of simple carbohydrate units. Since they are large in size they can be broken down into simple carbohydrates. They are further subdivided into
• Oligosaccharides – Composed of less than 10 monosaccharides parts
• Polysaccharides – Composed of a large number of polysaccharides. Example – Glycogen, starch, and cellulose

Test For Sucrose

The presence of sucrose can be tested in a sample using Benedict’s test.

Material Required

• Benedict’s Reagent
• Sugarcane extract
• Concentrated HCl
• NaOH solution
• Burner
• Dropper
• Test tube holder

Procedure

• Add a few drops of concentrated HCl using a dropper to the test tube that contains sugarcane extract
• Bring the contents of the test tube to a boil for 2 minutes.
• Hold the test tube securely with the help of a test tube holder
• Hydrolysis of sucrose takes place into fructose and glucose
• With the help of a dropper, add a few drops of NaOH solution to the test tube so as the solution turns alkaline
• Perform Benedict’s test to the solution to detect the presence of glucose.
• Add a few drops of Benedict’s reagent with the help of a dropper into the test tube holding the sample
• Hold the test tube securely with the help of a test tube holder, bring the sample to a boil over a burner for a few minutes.

Observation

The color of the solution switches from blur color to green color. From green, the color is finally switched to brick red or orange. This indicates that the solution contains glucose.

Test For Starch

Material Required

• Potato extract
• Iodine solution
• Dropper

Procedure

• Add a few drops(5 drops) of iodine solution with the help of a dropper to the test tube that is holding potato extract
• Notice the color change

Observation

The presence of starch in the potato extract is indicated when the color changes to a blue-black color.

Test For Proteins

The presence of proteins in a sample can be detected by the following tests:

• Biuret Test
• Xanthoproteic Test
• Million’s Test

1. Biuret Test

Material Required

• 1% CuSO4
• 40% NaOH solution
• Dropper
• Egg Albumin
• Test tube holder

Procedure

• Add a few drops of 40% NaOH solution with the help of a dropper into the test tube contained in the egg albumin
• With the help of a dropper, add 2 to 3 drops of 1% CuSO4 solution to the test tube in the egg albumin
• Stir the solution in order to mix it completely

Observation

The solution in the test tube appears to be violet in color. This indicates that the sample that is tested contains proteins.

2. Xanthoproteic Test

Material Required

• Ammonia solution
• Concentrated HNO3
• Dropper
• Egg albumin
• Test tube holder

Procedure

• Add a few drops(5 drops) of concentrated HNO3 with the help of a dropper into the test tube contained in the egg albumin
• Holding the test tube securely with a test tube holder, bring the sample to a boil over a burner. The test tube appears to have yellow precipitate.
• Add a few drops of ammonia solution to the test tube containing the sample.
• Stir the solution in order to mix it completely.

Observation

The sample contained in the test tube which appeared to have yellow precipitate changes its color to orange. This indicates that the sample contains proteins.

3. Million’s Test

Materials Required

• Million’s Reagent
• Egg albumin
• Dropper

Procedure

• With the help of a dropper, add a few drops of the Million’s reagent to the test tube holding egg albumin
• Let the sample remain for a while in the test tube. Observe the changes.

Observation

The sample indicates the presence of proteins when the color changes to pink.

Test For Fats

The presence of fats in a sample can be detected by the following tests:

• Sudan III Test
• Paper Spot Test

1. Sudan III Test

Materials Required

• Sudan III Solution
• Oil
• Dropper
• Egg Albumin

Procedure

• Add a few drops of the Sudan III reagent with the help of a dropper into the test tube contained in the egg albumin.
• Stir the solution completely

Observation

The presence of fat in the sample is indicated when pink color droplets appear in the test tube.

WRITE AT LEAST 4 PRECAUTIONS ON YOUR OWN .

HOME WORK TASK :

SEND THE   EMAIL WITH ANSWERS BY 1:00 PM TODAY AT : vcn@stcoumbas.edu.in

ANSWER THE FOLLOWING QUESTIONS :

Q.1. List examples of simple carbohydrates.

Q.2. What are peptide linkages?

Q.3. What is the xanthoproteic test?

Q.4. What do fats contain?.

Q.5. What is Fehling’s Test used for?

IF YOU HAVE FINISHED THIS WORK . YOU CAN DO YOUR REVISION FOR PA 1 & ASK YOUR DOUBTS.

THAT'S ALL FOR TODAY . I WILL SEE YOU NOW ON MONDAY ACCORDING TO DAY 1 TIMETABLE.