How to test presece of starch in food
Answers
Answer:
Step 1: A fresh leaf is taken.
Step 2: The leaf is boiled in water for few minutes to soften the cells in the leaf.
Step 3: Now, dip this leaf in iodine solution.
Step 4: The color of the leaf will changes into blue black color when iodine is added to it which shows the presence of starch in it.
Explanation:
What is Starch?
Starch is the major carbohydrate reserved in plant tubers and seed endosperm. It is stored in plant cells. Starch molecules arrange themselves in the plant in semi-crystalline granules. A starch molecule contains a large number of glucose molecules. These glucose molecules are arranged either as occasionally branched chains (amylopectin) or as unbranched chains (amylose). Amylose is a much smaller molecule than amylopectin.The colour of natural starch is milky white and the pure form of starch is insoluble in water and alcohol. Depending on the plant, starch generally contains 20-25% amylase and 75-80% amylopectin. Each plant species have a unique starch granular size. Rice starch is relatively small (about 2μm), while potato starches have larger granules (up to 100μm). Starch becomes soluble in water when heated.
Test for Starch
There are many types of carbohydrates. The main carbohydrates found in our food are in the form of starch and sugars. We can easily test if a food item contains starch.
Take small quantity of the food items to be tested.
Put 2-3 drops of iodine solution on it.
Observe the colour of the food item.
Blue-black colour indicates the presence of starch in the tested food item.