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Pectin

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Pectin is a complex substance known as a heteropolysaccharide. This means it is a large molecule made of different types of sugar units joined together.

Pektin1
Pektin1

In the plant world, pectin acts as a structural polymer. It is found within the cell walls and the middle lamella of terrestrial plants. The middle lamella is the specific layer that binds individual plant cells together. Without pectin, plant cells would not stay connected in a solid structure. This makes pectin vital for the physical integrity of many living things.

Inside the plant, pectin is built through a specific biological process. The Golgi apparatus produces small containers called vesicles. These vesicles carry pectin to the cell wall through a process called exocytosis.

Pektin2
Pektin2

Once in the wall, pectin allows the primary cell wall to extend. This extension is what enables a plant to grow larger. However, pectin also changes as a plant ages. During fruit ripening, enzymes called pectinase and pectinesterase begin to break the pectin down. This breakdown causes the middle lamella to fail and cells to separate. This is why ripe fruit feels much softer than unripe fruit.

Pektin3
Pektin3

The chemical structure of pectin is quite intricate. Its main component is galacturonic acid, which is a sugar acid derived from galactose. The systematic name for pectin is rhamno-galacturonic acid because its chain contains rhamnose alongside galacturonic acid. These rhamnose units act as "kinks" or bends in the chain. Because of these bends, pectin is not a simple straight line. Instead, it has "smooth" regions and "hairy" regions. The smooth regions are made of linear chains like homogalacturonan (HG). The hairy regions are more complex and branched, such as rhamnogalacturonan I (RG-I) and rhamnogalacturonan II (RG-II).

Scientists have studied pectin for a long time. In 1825, Henri Braconnot isolated and described galacturonic acid. Today, we produce pectin commercially as a white or light-brown powder. We extract it from various sources, though the amounts vary greatly. Citrus peels are very rich, containing about 30% pectin.

Цитрусовые
Цитрусовые

Other plants have much less. For example, apples contain 1–1.5%, carrots contain 1.4%, and oranges contain 0.5–3.5%. Even rose hips contain a significant 15%. These different sources change the chemical properties of the final powder.

Pectin is classified by its degree of methylation (DM). This refers to the ratio of esterified galacturonic acids to the total amount. We generally group them into three functional types. Pectic acids have a DM of less than 5%. Weakly methylated (LM) pectins have a DM of less than 50%. Highly methylated (HM) pectins have a DM greater than 50%. This chemistry determines how pectin behaves in food. HM-pectins form gels in acidic conditions with high sugar. In contrast, LM-pectins form gels by interacting with calcium ions. This is often described as an "egg box" model where calcium creates ionic bridges between chains.

In human nutrition, pectin serves as a soluble dietary fiber. It is not digested in the small intestine, but it is fermented in the large intestine. During this fermentation, microorganisms break it down into short-chain fatty acids. These fatty acids have a positive prebiotic effect on the body. Pectin also helps manage health by binding to cholesterol in the gastrointestinal tract. This increases viscosity, which reduces the absorption of cholesterol from food or bile.

Pectin
Pectin

Studies show that pectin can reduce LDL cholesterol levels by about 3% to 7%. It also helps slow down the absorption of glucose after eating.

Pectin connects many different scientific fields. In food science, it is a vital gelling agent for jams, jellies, and dessert fillings. In medicine, it is used in various medications and as a stabilizer for juices or milk. Even in extreme environments, pectin plays a role in survival. Some desert plants use pectin-rich surface layers to create a mucilage layer. This layer holds in dew, which helps the plant cells repair their DNA. This shows how a single molecule can support everything from a simple jelly to the survival of desert life.

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Pectin.jpg
File:Цитрусовые.jpg
Цитрусовые.jpg
File:Pektin1.svg
Pektin1.svg
File:Pektin2.svg
Pektin2.svg
File:Pektin3.svg
Pektin3.svg
File:Luna Barrera-Chamorro et al. Fig. 1.jpg
Luna Barrera-Chamorro et al. Fig. 1.jpg
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