Test for Carbohydrates, Proteins and Fats - MeitY OLabs

Summary

This video outlines various laboratory tests to detect carbohydrates, proteins, and fats in food samples. It covers tests for glucose using Benedict's reagent, sucrose hydrolysis, starch presence with iodine, and protein identification through the Biuret, Xanthoproteic, and Million’s tests. Additionally, it demonstrates fat detection using Sudan III reagent. Each procedure involves precise measurements, reagents, and techniques like water baths and test tube handling. The step-by-step explanations guide viewers through conducting each test to identify specific nutrients in samples such as banana extract, egg albumin, and sugar cane.

Takeaways

• 😀 Carbohydrate testing involves using Benedict's reagent to test for glucose in banana extract. The color changes from blue to orange or brick red, indicating the presence of glucose.
• 😀 Fats can be tested using Sudan 3 reagent, which creates pink droplets in oil, signaling the presence of fat.
• 😀 Proteins are detected by using biuret reagent, which produces a violet color when mixed with egg albumin, indicating protein presence.
• 😀 The Xanthoproteic test for proteins involves using concentrated HNO3, which forms a yellow precipitate that turns orange with ammonia solution, signaling protein.
• 😀 Starch presence is confirmed by adding iodine solution to potato extract, where the color turns blue-black, indicating starch.
• 😀 The Benedict's test for glucose requires heating a sample in a water bath, which shows a color change from blue to green to orange or brick red in the presence of glucose.
• 😀 Sucrose can be tested by first boiling the sample with concentrated HCl to hydrolyze it into glucose and fructose, followed by the Benedict’s test for glucose.
• 😀 For protein detection, the Millions test uses Millions reagent to create a pink color, indicating the presence of proteins in egg albumin.
• 😀 The process of testing for glucose in banana extract, sucrose in sugar cane extract, and starch in potatoes involves a series of reagent additions and heating steps.
• 😀 Testing for fats involves the use of Sudan 3 reagent, where the appearance of pink droplets indicates the presence of fats in oil.

Q & A

What is the purpose of the Benedict's reagent in the carbohydrate test?

Benedict's reagent is used to test for the presence of glucose in a sample. When glucose is present, the solution changes color from blue to green and eventually to orange or brick red.

How does the Benedict's test for glucose work in banana extract?

In the Benedict's test for glucose, a small amount of Benedict's reagent is added to the banana extract. The mixture is then heated in a water bath. The color change from blue to green and then to orange or brick red indicates the presence of glucose.

What is the role of HCl and NaOH in the sucrose test?

HCl is used to hydrolyze sucrose into glucose and fructose by boiling the solution, while NaOH is added afterward to make the solution alkaline, allowing for the subsequent Benedict's test to detect glucose.

What color change indicates the presence of starch in a sample?

The presence of starch is indicated by a color change to blue-black when iodine solution is added to the sample, such as potato extract.

How can proteins be tested using the biuret test?

In the biuret test, a small amount of NaOH solution is added to the sample followed by CuSO4. The appearance of a violet color indicates the presence of proteins.

What does a yellow precipitate in the xanthoproteic test indicate?

A yellow precipitate forms in the xanthoproteic test when concentrated nitric acid (HNO3) is added to a protein sample. After adding ammonia solution, the yellow precipitate turns orange, confirming the presence of proteins.

What is the significance of the pink color in the Million's test for proteins?

The appearance of a pink color in the Million's test, after adding Million's reagent to a sample, indicates the presence of proteins.

How does the Sudan III test detect the presence of fats?

The Sudan III test detects fats by adding a few drops of Sudan III reagent to the sample. If fats are present, pink droplets will appear, indicating the presence of fat in the sample.

What is the role of the Bunsen burner in these nutrient tests?

The Bunsen burner is used to heat the test tubes containing the sample and reagents in water baths during many of the tests, such as the Benedict's test, sucrose test, and others that require heating for proper chemical reactions.

How is the presence of glucose in sugar cane extract confirmed?

The presence of glucose in sugar cane extract is confirmed by performing the Benedict's test after hydrolyzing sucrose with HCl and making the solution alkaline with NaOH, followed by a color change in the Benedict's reagent.