Starch or amylum is a widely distributed natural polysaccharide consisting of a long polymer chain of glucose subunits. These subunits are joined together by a glycosidic bond. This carbohydrate is available in higher-living organisms and is used very much for energy storage.
It is a tasteless and fluffy white crystalline powdery material that is insoluble in cold water, alcohol, and other solvents. This polymer undergoes the gelatinization process after heating at a definite temperature. It can be converted into sugar like glucose or fermenting it into ethanol compound.
The d-glucose monomer of this molecule is made up of α‑(1→4) linkages and about 4-5% of α‑(1→6) branch linkages in amylopectin depending on its biological source. It contains (C6H10O5)n chemical formula, where “n” represents the number of individual units in this macromolecule. The molecular mass of this compound is about 162 g mol−1.
This compound is generally found in green plants, seeds, fruits, stems, roots, and tubers. It comprises two kinds of polysaccharides namely amylose and amylopectin. The discrete starch granules in the plasma of plant cells is firstly observed by Leeuwenhoek while observing plant cells under his microscope.
Starch Structure
This compound generally consists of a long chain of glucose subunits linked together by glycosidic bonds. The monomers of glucose subunits in this polysaccharide are linked together by glycosidic linkages. This linkage formed between the first carbon of one glucose monomer and the fourth carbon of the second glucose monomeric unit by the process of polymerization. This organic polymeric molecule consists of two types of complex polysaccharides namely amylose and amylopectin.
Amylose is a straight-chain polymer linked predominantly by α(1→4) glycosidic bonds, whereas amylopectin consists of glucose units are linked together by both α(1→4) glycosidic bonds (like amylose) and α(1→6) glycosidic bonds as well as contains branching at some points. The branching points occur between the first carbon of one glucose monomer and the sixth carbon of the second glucose monomeric units known as α(1,6) linkage causing a change in the direction of polymerization.
Starch Formula
It contains (C6H10O5)n chemical formula, where “n” represents the indefinite number of glucose monomers in this macromolecule. The glycosidic linkage is formed after interacts the free hydroxyl group on a carbon with the hydroxyl group of a second carbon resulting in the elimination of a water molecule.
Starch sources
This material is found largely in nature in the seeds, roots, and tubers of various plants. The richest sources of starch are rice, potatoes, beans, wheat, corn, cassava, whole-grain pasta, and minimally processed vegetables.
Preparation of Starch
This biomolecule is prepared commercially from plant parts like a tuber or seed containing a great amount of stored starch. These plant parts firstly crushed or ground extensively to prepare a pulp. The prepared pulp is mixed with water to remove any residual impurities from the resulting paste. The paste is then heated at a definite temperature till it is scorched and produces a powdery white-colored starch compound.
Starch Properties
This organic molecule is found abundantly in our nature and is used a lot by animals. There have various physical and chemical properties of this compound are as follows:
Physical Properties
Starch is completely insoluble in cold water and alcohol.
The density of this polymeric biomolecule varies greatly.
The autoignition temperature of this macromolecule is about 683 K.
The structure of this component can be known easily by the analysis with the XRD technique.
It can be decomposed while heating and doesn’t undergo melting or boiling.
It has a granular shape and it is a crystalline white-colored powdery material at room temperature and pressure.
The standard enthalpy of combustion of this organic compound is about 17.484 kJ.mol-1
Chemical Properties
The chemical properties of this compound are as follows:
It can hydrolysis and break into constituent glucose monomers while reacting with water.
The hydroxyl group of this compound undergoes acetylation with acetic anhydride in the presence of a base.
It shows the phosphorylation reaction while reacting with phosphorylating agents like phosphoric acid molecules and forms mono- or di-starch phosphate.
It undergoes oxidation with strong oxidizing agents like K2Cr2O7 and the terminal alcohol group of its glucose monomer converts into a ketone or a carboxylic acid group.
Applications of Starch
This multifunctional ingredient is used in various sectors for having great physical and chemical properties. The significant uses of this biomolecule are given below:
It is used very much in the food industry and acts as a thickening, stabilizing, and gelling agent. It is used heavily in the production of baking, sauces, gravies, soups, and desserts.
It acts as a binder in the wet granulation process of massing and screening and filler during tablet and capsule formulations in the pharmaceutical industry. Starch is also used in the production of wound healing products for the presence of the properties of biocompatibility and bioabsorbability.
This organic macromolecule is used in the field of textile industry to the production of fabric body and to create smoothness in fiber. It is used for the production of good adhesives.
This compound is an essential material in the paper industry because it increases the paper’s strength, printability, and surface quality.
This polysaccharide is used nowadays for the production of bioplastics.
Starch Side Effects
This important compound exists a lot on our planet and is consumed abundantly worldwide. This material should be consumed in moderate amounts because it may cause some problems if consumed excessively. The food containing this compound increases the risk of diabetes, weight gain, and various heart disorders. It may hamper the good blood circulation in our body if consumed large amounts. It may create lethargy and a feeling of fullness, as foods rich in starch are large amounts.
Conclusion
In conclusion, starch is the greatest biopolymer in our earth which plays an important role in human nutrition. It has various applications across various industries. The versatile properties and unique chemical structure make it more crucial to use it in food, pharmaceutical, adhesive, textile, and paper industries. The unique properties and functionality make it a subject of continued scientific and a lot of industrial applications.
References
Emeje, M., & Blumenberg, M. (2020). Chemical properties of starch. BoD–Books on Demand.
Eliasson, A. C. (Ed.). (2004). Starch in food: Structure, function, and applications. CRC press.
Frequently Asked Questions (FAQ’s) about starch
What is starch?
It is a polysaccharide consisting of a long polymer chain of glucose subunits. It is a combination of two types of complex polysaccharides namely amylose and amylopectin.
What is amylose?
Amylose is a straight-chain polymer linked predominantly by α(1→4) glycosidic bonds in glucose subunits.
What is amylopectin?
Amylopectin consists of glucose units that are linked together by both α(1→4) glycosidic bonds (like amylose) and α(1→6) glycosidic bonds as well as contains branching at some points.
What are the sources of starch?
The sources of starch are rice, potatoes, beans, wheat, corn, cassava, whole-grain pasta, and minimally processed vegetables.
What is the structure of starch?
This compound generally consists of a long chain of glucose subunits linked together by glycosidic bonds. The monomers of glucose subunits in this polysaccharide are linked together by glycosidic linkages in the process of polymerization.
What is the formula of starch?
This organic biopolymer contains (C6H10O5)n chemical formula, where “n” represents the indefinite number of glucose monomers in this macromolecule.
What is starch used for in the food industry?
It is used largely in the food industry as a thickening, stabilizing, and gelling agent. It is also used heavily in the production of baking, sauces, gravies, soups, and desserts.
What is starch used for in the pharmaceutical industry?
It is used in the pharmaceutical industry for the wet granulation process of massing and screening and filler during tablet and capsule formulations due to having the properties of biocompatibility and absorbability.
What is starch used for in textile industry?
It is used in the textile industry for the production of fabric bodies and to create smoothness in fiber.