Question

3. Liquid Coffee Mate has many ingredients including corn syrup solids, vegetable oil, and sodium caseinate (a milk derivative). Classify each of these substances into the following categories of macromolecules: carbohydrates, lipids, or proteins. Which substance(s) is/are responsible for the result you obtained with the biuret reagent?

4. Research the substance pepsin. What is it used for? If you were to test the enzyme amylase, what result would you expect with the biuret reagent? Why?

5. You enjoy the following snack one afternoon: a can of Pepsi, pretzels, and sliced apples with peanut butter. Would any of these four food items yield a positive result with biuret reagent? If so, which one(s) and why?

Answer 1

3.Liquid coffee mate has many ingredients like corn syrup solids,vegetable oil, and sodium casinate.

corn syrup solid -carbohydrate

vegetable oil -lipid

sodium caseinate-protein.

Biuret reagent is an aqueous solution of potassium sodium tartarate treated with cupric suphate and sodium hydroxide,

Protein i.e. sodium caseinate is responsible for the result you obtained with the biuret reagent.

Protein test-bureit solution

• In a test tube, add 40 drops of liquid to be tested
• Add 3 drops of Biuret reagent solution (blue colour) to the test tube. Shake gently to mix.
• Note any color change. Proteins will turn solution blue to pink or purple.

4.Pepsin is used for digestion of food in the body.

It also helps in breaking the protein part of the food we eat into small parts and also helps in absorption of nutrients.

If enzyme amylase is tested with biuret reagent will remain positive as is gelatin. a soluble protein.

5.Out of the four food items given in the question , peanut butter will yield a positive result with biuret reagent. Because peanut butter is a good source of protein and contains 25 gm of protein.

As biuret reagent shows positive test with protein, so,Peanut butter will show positive result.