What is the Difference Between Pectin and Lignin

The key difference between pectin and lignin is that pectin is an acidic heteropolysaccharide found in the middle lamella, the primary and secondary cell wall of the plants, while lignin is a polyphenyl propane polymer found in the middle lamella and secondary cell wall of the plants.

Middle lamella is a layer involved in joining the primary cell walls of two adjacent plant cells together. The middle lamella is made up of calcium and magnesium pectates. Lignin is also found in the middle lamella. Moreover, it is difficult to distinguish the middle lamella from the primary cell wall, especially in the cells that have thick secondary cell walls. Pectin and lignin are two organic compounds found in the middle lamella and cell walls of the plants.

CONTENTS

1. Overview and Key Difference
2. What is Pectin 
3. What is Lignin
4. Similarities – Pectin and Lignin
5. Pectin vs Lignin in Tabular Form
6. Summary – Pectin vs Lignin

What is Pectin?

Pectin is an acidic heteropolysaccharide present in the middle lamella, the primary and secondary cell walls of terrestrial plants. It is a structural polysaccharide. The main component of pectin is galacturonic acid. Galacturonic acid is a sugar acid derived from galactose. Pectin was first isolated and described by a French chemist known as Henri Braconnot. Commercially, it is produced as a white to light brown powder. Pectin is normally extracted from citrus fruits for commercial purposes. It is used as a gelling agent. This organic compound can be found particularly in jams and jellies. It is often used as a stabilizer in dessert fillings, medicine, and sweets. Furthermore, in fruit juices and milk drinks, it is used as a source of dietary fiber.

Pears, apples, guavas, quince, oranges, plums, gooseberries, and other citrus fruits contain large amounts of pectin, while soft fruits such as cherries, grapes, and strawberries contain small amounts of pectin. At the joint FAO/WHO expert committee report on food additives and in the European Union, no numerical acceptable daily intake has been set for pectin. Therefore, pectin is considered safe for human consumption.

What is Lignin?

Lignin is an organic polymer that forms the key structural material in the support tissues of most plants. This polymer can also be found in red algae. Biochemically, it is a polyphenyl propane polymer, and it is found in the middle lamella and secondary cell walls of the plants. It is important in the formation of cell walls, especially in wood and bark. It provides rigidity and does not rot very easily.

Lignin was first described by Swiss botanist A.P. de Candolle in 1813. The biological function of lignin is filling the spaces in the cell wall between cellulose, hemicelluloses, pectin components in vascular and support tissues such as xylem, vessel elements, and sclereid cells. Lignin also plays an important role in conducting water and aqueous nutrients in plants stems.  The most notable function of lignin is the support through the strengthening of wood in vascular plants.  Moreover, lignin also confers disease resistance, making the plant cell wall less accessible to cell wall degradation. Commercially, lignin is used as a super green fuel for use in fuel cells.

What are the Similarities Between Pectin and Lignin?

• Pectin and lignin are two organic compounds.
• Both compounds are found in the middle lamella and cell walls of terrestrial plants.
• They are biopolymers.
• Both compounds are commercially used for different purposes.

What is the Difference Between Pectin and Lignin?

Pectin is an acidic heteropolysaccharide present in the middle lamella and cell wall of the plants, while lignin is a polyphenyl propane polymer present in the middle lamella and secondary cell wall of the plants. Thus, this is the key difference between pectin and lignin. Furthermore, pectin was described by a French chemist known as Henri Braconnot, whereas lignin was described by a Swiss botanist known as A.P. de Candolle.

The below infographic presents the differences between pectin and lignin in tabular form for side by side comparison.

Summary – Pectin vs Lignin

Pectin and lignin are two biopolymers. They are found in the middle lamella and cell walls of terrestrial plants. Pectin is an acidic heteropolysaccharide found in the middle lamella, the primary and secondary cell wall of the plants, while lignin is a polyphenyl propane polymer found in the middle lamella and secondary cell wall of the plants. So, this is the key difference between pectin and lignin.

Reference:

1. “Pectin.” An Overview | ScienceDirect Topics.
2. “Lignin.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Pectin” By Simann13 – Own work (CC BY-SA 3.0) via Commons Wikimedia

2. “Lignin structure” By Karol Głąbpl.wiki: Karol007commons: Karol007e-mail: kamikaze007 (at) tlen.pl – own work from: Glazer, A. W., and Nikaido, H. (1995). Microbial Biotechnology: fundamentals of applied microbiology. San Francisco: W. H. Freeman, p. 340. ISBN 0-71672608-4This W3C (CC BY-SA 3.0) via Commons Wikimedia