Starch

Plants make starch to save food.

They use sunlight to make food. Then, they pack it into tiny grains.

These grains stay in seeds and roots. This helps the plant grow later. We eat starch in corn and rice.

It is also in potatoes and wheat. Starch can even be used as glue. It is a very helpful thing!

Plants make starch to save food for later.

They use sunlight to make a sugar called glucose. Most plants pack extra glucose into tiny grains. We call these grains starch granules.

These granules are found in seeds, roots, and fruits. This helps the plant grow during the next season. Starch is made of two main parts. One part is amylose, which is a long chain.

The other part is amylopectin. This part has many branches.

Humans eat a lot of starch every day. It is in foods like rice, corn, and potatoes.

People also use starch in many other ways. It can be used as a glue for paper. It can also make clothes feel stiff when you iron them. In factories, starch is turned into sugar. These sugars can even make fuel for cars.

Starch is a very important part of our world.

Starch is a very important part of life on Earth. It is a type of carbohydrate that plants make to store energy.

This energy helps plants survive when they cannot make food from sunlight. Because it is so common, starch is the most frequent carbohydrate in human diets. You can find it in many staple foods like wheat, potatoes, corn, rice, and cassava.

Pure starch looks like a white powder. It has no taste and no smell. It also does not dissolve in cold water or alcohol.

Starch is made of many tiny units called glucose joined together.

These units form two different kinds of molecules. The first is amylose, which is a long, straight chain. The second is amylopectin, which is highly branched like the limbs of a tree.

Most plants have a mix of both. Depending on the plant, it might be 20% to 25% amylose and 75% to 80% amylopectin. Plants pack these molecules into tiny, hard grains called starch granules.

These granules are stored in parts like seeds, roots, and tubers. This allows the plant to grow again in the next season.

Humans have used starch for a very long time.

Scientists found starch grains on grinding stones in Europe from 30,000 years ago. Even older starch grains from sorghum were found in Mozambique from 100,000 years ago. In Ancient Egypt, people used wheat starch paste as a glue for papyrus.

Around 77 to 79 CE, a writer named Pliny the Elder described how to extract starch. Romans used it for hair powder and to thicken their sauces. Later, in China, rice starch was used to treat paper surfaces starting in 700 CE. In England, people used laundry starch to make fancy ruffed collars in the 1500s.

Today, the starch industry is huge and works all over the world.

In 2011, the European Union produced about 11 million tonnes of starch. A large part of this was used to make sweeteners. In 2017, the United States produced about 27.5 million tons of starch. Much of the American starch is turned into different kinds of syrups.

Some starch is even used to make ethanol, which is a type of biofuel. Factories use machines to grind, wash, and dry crops to get the starch out. They can get starch from more than 50 different types of plants.

Starch connects to many things you see in your daily life. If you mix starch with warm water, it creates a thick paste. This paste can be used as a glue or a thickener in food. It is also used as an adhesive in the process of making paper. You might also see starch used on clothes. People apply it to fabrics before ironing to make them feel stiff. Even animals have something similar to starch. Animals use a highly branched molecule called glycogen to store their own energy. This shows how many different living things use similar ways to save food for later.

Starch, also known as amylum, is a polymeric carbohydrate. It consists of many glucose units joined by glycosidic bonds. Plants produce this polysaccharide to store energy for later use. It is the most common carbohydrate in human diets worldwide. We find it in staple foods like wheat, potatoes, maize, rice, and cassava.

Pure starch is a white, tasteless, and odorless powder. It does not dissolve in alcohol or cold water.

Starch is made of two distinct types of molecules. The first is amylose, which forms linear and helical chains. The second is amylopectin, which is a highly branched molecule.

Most plants contain a specific ratio of these two types. Depending on the plant, starch may contain 20% to 25% amylose by weight. The remaining 75% to 80% is usually amylopectin. Some plants produce waxy starches that contain only amylopectin. Examples include waxy maize, glutinous rice, and waxy potato starch.

Plants create starch through a complex biological process. First, they use photosynthesis to make glucose from water and carbon dioxide. This glucose is then converted into starch within specialized structures called plastids. These plastids include chloroplasts in green tissues and amyloplasts in storage tissues.

The process begins when glucose 1-phosphate is converted into ADP-glucose. This step requires energy from ATP and uses an enzyme called glucose-1-phosphate adenylyltransferase. Starch synthases then add the ADP-glucose to a growing chain via α-1,4-glycosidic bonds. To create the branches in amylopectin, starch branching enzymes introduce α-1,6-glycosidic bonds.

Starch is stored in semicrystalline granules to save space. These granules are osmotically inactive, meaning they do not cause cells to swell with water. This allows plants to pack energy very compactly. Different plants produce granules of different sizes. Rice starch granules are small, measuring about 2 μm. Potato starch granules are much larger, reaching up to 100 μm. Wheat starch is unique because it has a bimodal size distribution. This means it contains both small and large granules ranging from 2 to 55 μm.

Human history is deeply connected to the use of starch. Researchers found starch grains from bullrushes on European grinding stones dating back 30,000 years. Even older sorghum starch grains were found in Mozambique from 100,000 years ago.

In Ancient Egypt, wheat starch paste was likely used to glue papyrus. Around 77–79 CE, Pliny the Elder described starch extraction in his work, *The Natural History*. Romans used starch in cosmetics, hair powder, and thick sauces. In China, rice starch was used to treat paper surfaces starting in 700 CE. By the 1500s, laundry starch became essential for making ruffed collars in England.

Modern industry processes massive amounts of starch every year. In 2011, the European Union produced about 11 million tonnes of starch. About 60% of this was used for food, mostly as glucose syrups.

In 2017, the United States produced approximately 27.5 million tons of starch. A large portion of American starch is converted into high fructose syrup and glucose syrups.

Factories use wet grinding, washing, and drying to refine starch from over 50 plant types. Some starch is also processed into ethanol to create biofuel.

Starch serves many practical roles in daily life and science. When mixed with warm water, it creates a paste used for thickening or gluing. This is seen in wheatpaste or as an adhesive in papermaking. It is also used to stiffen textiles before ironing. Interestingly, starch is similar to the energy reserves found in animals. Animals use a molecule called glycogen to store energy. Glycogen is simply a more highly branched version of amylopectin. This shows how different life forms use similar chemical structures to manage energy.