Are you looking for the details of isolation of starch from potatoes procedure? Here are the complete details about this concept.

Potatoes are a widely used staple food and are a rich source of starch, a complex carbohydrate that is a significant energy source for humans. Isolating starch from potatoes is a common practice in the food industry, as it is used in many food products like bread, pasta, and confectioneries.

Potatoes are one of the most versatile and widely consumed vegetables worldwide. They are not only delicious but also rich in various nutrients. One of the key components of potatoes is starch, which serves as an essential energy source for the plant. This article will explore the process of isolating starch from potatoes, highlighting its uses and significance in various industries.

Potatoes are a staple food for many cultures, containing a significant amount of starch. Starch is a complex carbohydrate composed of glucose molecules, making it an important energy source for plants and humans. Extracting and isolating starch from potatoes is a process that enables its utilization in various industries.

The isolation of starch from potatoes can be done through several methods. However, this article will discuss the practical protocol for isolating starch from potatoes, which involves simple steps and readily available equipment.

Read on to learn how to extract starch from potatoes using this practical protocol.

isolation of starch from potatoes

What is Starch?

Starch is a polysaccharide, a long chain of glucose molecules linked together. It is a storage form of energy in plants, allowing them to survive adverse conditions.

Starch can be found in many plant-based foods, with potatoes being one of the richest sources. It is unique properties, and versatile nature makes it valuable for numerous applications.

Importance of Starch

Starch has wide-ranging applications across multiple industries. It is commonly used in the food industry as a thickening agent, stabilizer, and binder.

Starch is also utilized in the paper and textile industries, providing strength and improving the quality of the end products.

Additionally, starch is a vital component in producing biodegradable plastics, adhesives, and even pharmaceuticals.

Isolation of Starch from Potatoes

Isolating starch from potatoes involves several steps to ensure its purity and usability. Let’s explore the process in detail:

Step 1: Preparation of Potatoes

  • Select fresh and mature potatoes for the extraction process.
  • Wash the potatoes thoroughly to remove any dirt or debris.
  • Peel the potatoes to remove the outer skin.
  • Cut the potatoes into small pieces for easier handling during extraction.

Step 2: Extraction of Starch

  • Place the cut potatoes in a container and cover them with water.
  • Allow the potatoes to soak for some time to soften them.
  • After soaking, vigorously stir the potatoes to release the starch.
  • The starch will separate from the potatoes and form a milky white liquid.

Step 3: Separation and Purification

  • Pour the milky liquid into another container, allowing it to settle.
  • As the liquid settles, the starch will sink to the bottom.
  • Carefully pour off the excess liquid, leaving the starch sediment.
  • Rinse the starch sediment multiple times to remove impurities.
  • Finally, dry the starch to remove any remaining moisture, producing pure starch powder.

Uses of Starch

Starch has a multitude of applications across various industries. Here are some common uses:

  1. Food Industry: Starch is used as a thickening agent in sauces, soups, and desserts. It provides viscosity and texture to these products.
  2. Paper Industry: Starch is used in papermaking to improve paper’s strength, smoothness, and printability.
  3. Textile Industry: Starch is employed in textile sizing to increase the stiffness and handle of fabrics.
  4. Pharmaceutical Industry: Starch is used as a binder to produce tablets and capsules.
  5. Biodegradable Plastics: Starch is utilized as a raw material for producing environmentally friendly and biodegradable plastics.

Isolation of Starch from Potatoes (Practical Procedure)


To isolate starch from potatoes

Materials required

Before we start the isolation process, let’s first look at the materials required for the protocol.

  • Potatoes
  • Distilled Water
  • Hydrogen Peroxide (H2O2)
  • Sodium Chloride (NaCl)
  • Cheesecloth or Muslin Cloth
  • Beaker
  • Bunsen Burner
  • Funnel
  • Glass Rod
  • Spatula
  • Petri Dish
  • Analytical Balance


Now that we have prepared our materials and solutions, we can begin the isolation process.

  • Wash the potatoes thoroughly to remove any dirt or debris.
  • Peel the potatoes and cut them into small pieces.
  • Place the potato pieces in a blender or food processor and add enough distilled water to cover them.
  • Blend the potato pieces and water until the mixture is smooth and well-mixed.
  • Pour the potato mixture through a cheesecloth or filter paper to remove any solid pieces. Collect the liquid in a glass or plastic container.
  • Allow the potato mixture to settle for a few minutes so that the starch can separate from the liquid.
  • Pour off the liquid, leaving the starch at the bottom of the container.
  • Rinse the starch several times with distilled water to remove any impurities.
  • Transfer the starch to a funnel lined with filter paper and allow it to drain.
  • Place the funnel and filter paper in a glass or plastic container and add enough ethanol to cover the starch.
  • Allow the starch to soak in the ethanol for at least 30 minutes to remove any remaining impurities.
  • Place the glass or plastic container on a hot plate or stove and stir the ethanol and starch mixture to 60-70°C, stirring constantly.
  • Allow the mixture to cool to room temperature, and then filter off the excess ethanol.
  • Allow the starch to dry completely before using it for any further applications.

Filtration and Drying of Isolated Starch

After isolating the starch from the potatoes, the next step is to filter and dry it.

  • Use a funnel and filter paper to filter the starch to remove any impurities.
  • Place the filtered starch in a petri dish and allow it to dry in a warm place.
  • Once the starch is completely dry, weigh it.

Properties of starch

  • Examine a little starch under a microscope. Note down the characteristic shape of the granules.
  • Boil a small amount of starch with water. Cools, then add iodine solution. Note the color.

Preparation of Soluble Starch

  •  Suspend three grams of raw potato in 100ml of redistilled 95% alcohol. Add 0.75ml of concentrated HCI.
  • Heat it over boiling water with a reflux condenser for twenty minutes.
  • Add at once 1 N NaHCO3Solution to neutralize 0.75ml of acid using methyl orange as an indicator.
  • Decant through a filter paper and wash with several portions of alcohol. Dry at room temperature and pressure it.


The experiment shows that starch can be extracted from potatoes having asymmetric rings and rounded rings. They show a blue color with iodine, which indicates the presence of starch.

Isolation of Starch from Potatoes
Observation of starch granules under the light microscope

The net yield of starch from potatoes in 250 grams of potatoes Solution is __________ /250 grams.

Science behind the Isolation of Starch from Potatoes

The isolation of starch from potatoes is based on the fact that potatoes are a rich source of starch.

When potatoes are boiled in a 3% hydrogen peroxide solution, the cells break down, releasing the starch granules.

Adding a 10% sodium chloride solution to the filtrate causes the starch to settle at the bottom of the beaker, making it easy to isolate.

Benefits of Isolating Starch from Potatoes

Isolating starch from potatoes has several benefits, including:

  • Starch extracted from potatoes is a natural and renewable source of energy.
  • The isolated starch can be used in various food products such as bread, pasta, and confectioneries.
  • The process of isolating starch from potatoes is simple and requires only a few materials and solutions.
  • The isolated starch is free from impurities and is of high quality.

Frequently Asked Questions (FAQs)

What can I do with the isolated starch? 

The isolated starch can be used in various food products such as bread, pasta, and confectioneries.

Is it necessary to dry the isolated starch? 

It is necessary to dry the isolated starch to remove any moisture and impurities.

Can I use table salt instead of sodium chloride to isolate starch from potatoes? 

No, table salt contains iodine and other additives that can affect the quality of the isolated starch. It is recommended to use sodium chloride.

Is it necessary to use a 3% hydrogen peroxide solution to isolate starch from potatoes? 

Yes, a 3% hydrogen peroxide solution is necessary as it breaks down the potato cells and releases the starch granules.

Final words

The isolation of starch from potatoes is a time-consuming, temperature-sensitive, and chemically unstable process. There are three methods of obtaining starch from potatoes: the acid-treated process, the enzyme process, and the cold-water process. The acid-treated process, which is the oldest method, is the most expensive.

Isolating starch from potatoes using the practical protocol is a simple and effective process. With just a few materials and solutions, you can extract high-quality starch from potatoes used in various food products.

The enzyme process is the most widely used method today. In this process, the potatoes are steamed and then treated with enzymes. The cold-water process, used in some developing countries, involves washing the potatoes in cold water to remove starch.

We hope this step-by-step guide has been helpful, and you can now confidently remove starch from potatoes for your use.

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