What is Starch?

Starch is a tasteless, fluffy white powder that is insoluble in cold water, alcohol, and other solvents. Starch is a polysaccharide made up of 1,4 linkages between glucose monomers. The chemical formula of the starch molecule is (C6H10O5)n.


Starch is made up of long chains of sugar molecules that are connected together. The linear polymer amylose is the most basic form of starch, while amylopectin is the branched form. Starch’s primary role is to help plants store energy. In an animal’s diet, starch is a source of sugar. Amylase, an enzyme contained in saliva and the pancreas that breaks down starch for energy, is used by animals to break down starch.


Preparation of Starch Solution

Commercial starch is made by crushing or grinding starch-containing tubers or seeds, then combining the pulp with water, removing any residual impurities, and drying the resulting paste. Starch is used in the processing of paper to improve its strength and in the surface sizing of paper. 

To make a starch indicator solution, dissolve 1 gram of corn or potato starch in 10 mL distilled water, shake well, and pour into 100 mL boiling distilled water. Boil for 1 minute, stirring continuously. Allow time for cooling. Decant the supernatant and use it as the indicator solution if a precipitate forms.

Preparation of Starch Solution

The starch solution was prepared by heating in an autoclave at 125oC for 300 minutes., followed by a rapid cooling in a water bath, and then homogenizing in a warm blender for 30 seconds.

The starch solution thus prepared was examined under microscope to confirm that all the starch granules had been ruptured to form a colloidal dispersion. In addition, a few preliminary flocculation tests were made with this solution and the results were compared with a rusticized starch solution. Virtually identical results justified the present preparation methods for the following tests, unless stated otherwise. To minimize the effects of microbiological decomposition, fresh starch solutions were prepared each day. Chemically modified starches, both cationic and anionic, were solubilized in the same manner.

General Properties of Starch

The properties of starch are numerous. The structure of starch, especially amylose content, granule size distribution, granule form, granule-granule interaction, granule volume fraction, and continuous phase viscosity, all influence its rheological properties.

Starch has a number of properties. 

  • Starch as carbohydrate – Our main source of carbohydrate is starchy foods, which play an important role in a healthy diet. Potatoes, bread, rice, pasta, and cereals are examples of starchy foods.
  • Starch as polysaccharide – Polysaccharides are a form of biological polymer that is widely used. In living organisms, their role is typically related to structure or storage. In plants, starch (a polymer of glucose) is present in the forms of amylose and branched amylopectin and is used as a storage polysaccharide.
  • Starch as a non-reducing sugar – It takes more than one hemiacetal “needle” in a haystack of “acetals” to give a positive sugar-reduction test. As a result, polysaccharides are not classified as reducing sugars. Starch, for example, results in a negative test. Starch and sucrose are both blue, indicating that they are non-reducing sugars.

Uses of Starch

  • Foods that are high in starch are a good source of nutrition. They are broken down into glucose, which is the body’s main fuel, particularly for our brain and muscles, after they are ingested. B vitamins, iron, calcium, and folate are all essential nutrients found in starchy foods.
  • The most common use of starch as a pharmaceutical excipient is in the formulation of tablets and other solid dosage forms as a binder and disintegrate. From the standpoint of the pharmaceutical industry, its behaviour in the presence of water is therefore its most valuable property.
  • The sole aim of starch in terms of dietary function is to turn glucose into energy for your body. Glucose is the only carbohydrate that your body can use. Glucose circulates in your bloodstream, where it is absorbed by cells and used as a source of energy.
  • Food starches are commonly used as thickeners and stabilizers in foods like puddings, custards, soups, sauces, gravies, pie fillings, and salad dressings, as well as in the production of noodles and pastas.
  • Starch is made up of long chains of sugar molecules that are connected together. Starch’s primary role is to help plants store energy. In an animal’s diet, starch is a source of sugar. Amylase, an enzyme contained in saliva and the pancreas that breaks down starch for energy, is used by animals to break down starch.

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Frequently Asked Questions – FAQs

What is starch used for in chemistry?

Starch is used in a variety of industries, including the production of paper, textiles, pharmaceuticals, and biodegradable polymers, as well as a food additive. Amylose and amylopectin are two separate molecules that make up starch.

Is Starch and Glucose the same?

Starch and cellulose are two polymers that are very similar. They’re both made of the same monomer, glucose, and have glucose-based repeat units. There is just one distinction. The glucose repeat units in starch are all directed in the same direction.

What is the difference between carbohydrate and starch?

Fibre, starch, and sugar are the three elements of carbohydrates. Sugar is a basic carb, while fibre and starch are complex carbs. The nutrient content of food is determined by how much of each of these is present in it.

Why is starch used as an indicator?

Since starch transforms to a deep dark blue colour when iodine is present in a solution, it can be used as a titration indicator. When starch is heated in water, it decomposes and develops beta-amylose. As beta-amylase reacts with iodine, it turns a dark blue hue.

Why is the starch indicator added at the end point?

When the iodine solution is poor, starch is added near the end. When exposed to high concentrations of iodine, starch, being a complex molecule, traps the iodine molecules. Since the trapped iodine molecules do not react with Na, S, or O, the endpoint is diffuse.

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