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Mindful Eating: A Pathway to Health - Test for Starch

Grade 6CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Nutrients are the chemical substances in food that our body needs to grow, repair itself, and provide energy. The major nutrients include carbohydrates, proteins, fats, vitamins, and minerals.

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Carbohydrates are the main energy-giving nutrients. In our food, they are mainly present in the form of starch and sugars.

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The presence of starch in a food item can be tested using a dilute iodine solution.

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Iodine Solution Preparation: A dilute solution of iodine can be prepared by adding a few drops of tincture iodine to a test tube half-filled with water.

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Procedure for Starch Test: Take a small quantity of a food item or a raw ingredient. Put 2-3 drops of dilute iodine solution on it.

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Observation and Inference: If the food item turns blue-black, it indicates that it contains starch. If there is no color change (stays yellowish-brown), starch is absent.

📐Formulae

Starch+Iodine Solution (Dilute)→Blue-Black Color Complex\text{Starch} + \text{Iodine Solution (Dilute)} \rightarrow \text{Blue-Black Color Complex}

Dilute Iodine=Tincture of Iodine+Water\text{Dilute Iodine} = \text{Tincture of Iodine} + \text{Water}

💡Examples

Problem 1:

A student takes a slice of raw potato and adds two drops of iodine solution to it. What color change will they observe, and what does it signify?

Solution:

The student will observe the potato slice turning a deep blue-black color.

Explanation:

Potatoes are rich in starch. When iodine reacts with starch, it forms a blue-black complex. This confirms the presence of carbohydrates (starch) in the potato.

Problem 2:

During an experiment, a student tests boiled rice and egg white with iodine solution. Predict the results for both.

Solution:

  1. Boiled rice will turn blue-black.
  2. Egg white will not change color (it remains yellowish-brown).

Explanation:

Rice is a rich source of starch, so it reacts with iodine. Egg white primarily contains protein and does not contain starch, hence it does not show the blue-black color change.

Problem 3:

If a sample of wheat flour shows a blue-black color with iodine, and we assume the starch content per unit is 15 units15\text{ units}. If we double the sample size, how many units of starch are reacted? (Represent as addition).

Solution:

15+1530\begin{array}{r} 15 \\ + 15 \\ \hline 30 \end{array}

Explanation:

By doubling the sample size of the wheat flour, the total starch content present for the reaction also doubles, resulting in 3030 units of starch being tested.