Starch – Definition, Structure, Formula

Starch is a form of carbohydrate usually found in all the green plants. Starch is a tasteless, soft, white powder, starch is insoluble in alcohol, cold water, and other solvents. The starch molecule’s fundamental chemical formula is (C₆H₁₀O₅)_n. Plants use the extra glucose generated during photosynthesis to make starch in their green leaves, which acts as a store of food for the plant.

In this article, we will understand the concepts related to Starch in detail, also we will learn what are starch-rich foods and how to test the presence of starch.

What is Starch

Starch, or amylum, is a complex carbohydrate that exists in many foods, including grains, vegetables, and fruits. Starchy foods are a vital component of a balanced diet. These starch polymers are produced by plants in order to store the glucose produced during photosynthesis. Foods high in starch are therefore excellent sources of energy.

Upon consuming starchy foods, the body converts the natural polymers into glucose units, which power every part of the body. In addition to being a component of a healthy diet, starch is used in the production of many goods in the food, paper, and pharmaceutical industries.

Definition of Starch

Starch is a polysaccharide comprising glucose monomers joined in α 1,4 linkages.

Starch Formula

Starch Formula is given as (C₆H₁₀O₅)n

Since, starch is a polymer of glucose(C₆H₁₂O₆), its molecular formula is given as the molecular formula of its repeating unit also called monomer which polymerise in ‘n’ number to form starch.

Structure of Starch

Strcuture of Starch is a mix of 2 different polysaccharides which are joined by Oxygen atom often referred as glycosidic bond.

• Amylose: A lengthy chain of α-glucose monomers connected by 1,4-glycosidic bonds is known as amylose. The chain is held together by hydrogen bonds as it spirals around.
• Amylopectin: Amylopectin is a polymer composed of branched chains of α-glucose monomers connected by 1,4- and 1,6-glycosidic bonds. The connections that create branches are made of 1,6-glycosidic bonds.

Properties of Starch

The properties of starch are mentioned below:

• When starch is at room temperature and pressure, it is a white powder.
• Starch breaks down during heating; it does not melt or boil.
• Starch has an autoignition temperature of roughly 683 K.
• Starch comes in wide variations in density.
• Both alcohol and cold water won’t dissolve it.

Preparation of Starch

We know that the starch is present in the plant, there are following ways to extract and prepare starch for our use. We will also learn how to confirm the presence of starch in a source

Steps for Preparation of Starch

• Select a good source of plants to produce starch from. Potatoes, corn, wheat, and tapioca are typical sources.
• Take foreign materials and impurities out of the raw material by cleaning and washing it.
• Crushing or grinding seeds that contain starch.
• Combining the pulp with water.
• Dry the resulting paste.

Steps for Preparation of Starch Indicator Solution

• To make a smooth paste, mix in a small amount of distilled water with the starch powder in the mixing bowl.
• Boil the above solution formed for a minute and stir continuously.
• Allow the solution some time for cooling.
• If a precipitate forms, use the supernatant as the indicator solution and decant it in the final step.

Test for Starch

The presence of starch is confirmed by Iodine Tincture Solution Test. Iodine Ticture is a deep blue coloured solution use to test the presence of starch in a source. To test the presence of starch put few drops of iodine tincture solution on a source let’s say leaf or potato, it will turn blue-black which confirms the presence of starch in the source.

Sources of Starch

A polysaccharide called starch hydrolyzes to release glucose. The majority of starches and starchy foods used in food preparation come from roots (cassava, tapioca, arrowroot), potatoes, and sweet potatoes, as well as cereals (rice, wheat, maida, sago, and barley). Granules, which are microscopic particles, contain starch.

Starch Foods

The list of starch rich foods are mentioned below:

• Grains: Rice (white or brown), Wheat (bread, pasta, couscous), Barley, Quinoa, Oats
• Root Vegetables: Potatoes ,Sweet potatoes, Yams, Carrots
• Legumes: Beans (black beans, kidney beans, pinto beans), Lentils, Chickpeas, Peas
• Corn and Corn Products: Corn kernels, Cornmeal, Popcorn
• Processed Foods: Cereals, Crackers, Pretzels

Health Benefits of Starch

There are numerous health benefits of starch. Some of them are mentioned below:

• Energy Source: The body uses starch as its main energy source. It releases energy steadily and continuously during digestion into glucose, which supports daily activities and biological functions.
• Dietary Fiber: Dietary fiber can be found in many starch-rich foods, particularly whole grains and some vegetables. In addition to encouraging regular bowel movements and assisting in the prevention of constipation, fiber is crucial for digestive health.
• Blood Sugar Control: Eating complex carbs, such as starch, can help improve blood sugar regulation.
• Gut Health: As a prebiotic, resistant starch is a form of starch that evades digestion in the small intestine and makes it all the way to the colon.
• Heart Health: One common source of starch is whole grains, which have been linked to a lower risk of cardiovascular diseases.

Uses of Starch

The uses of starch are listed below:

• Starch is used as a binder in the pharmaceutical industry for tablet formulations.
• Starch is commonly used in the iodine test as an indicator for the presence of starch in a solution.
• Starch is widely used as a thickening agent in soups, sauces, gravies, and puddings.
• Foods that are high in starch are a good source of nutrition.

FAQs on Starch

1. What is Starch?

Starch is a soft, white, tasteless powder that is insoluble in cold water, alcohol, or other solvents.

2. Is Starch good?

Yes, Starchy foods are a good source of energy and the main source of a range of nutrients in our diet.

3. What is the Use of Starch?

Starchy foods are our main source of carbohydrate and have an important role in a healthy diet.

4. What is the Chemical Formula of Starch?

The starch molecule’s fundamental chemical formula is (C₆H₁₀O₅)_n.

5. What are the Examples of Starch Rich Foods?

Foods such as potatoes, bread, rice, pasta, and cereals are rich in starch

6. What are Non-Starch Polysaccharide?

Non-Starch Polysaccharides also called NSP are the polysachharides which are not starch. Examples include cellulose, gums, chitin, inulin etc.

7. What are Starchy Vegetables?

The vegetables which has high starch content are starchy vegetables include. Examples include, corn potatoes, beets, turnip etc.

8. What is the Content of Starch in Potato?

On an average, a potato contain approx 18% of starch of its weight.