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Pectin ( : 'congealed' and 'curdled') is a heteropolysaccharide, a structural polymer contained in the cell walls and of terrestrial plants. The principal chemical component of pectin is galacturonic acid (a sugar acid derived from galactose) which was isolated and described by Henri Braconnot in 1825. Commercially produced pectin is a white-to-light-brown powder, produced from for use as an edible gelling agent, especially in and jellies, dessert fillings, medications, and sweets; as a food stabiliser in fruit juices and milk drinks; and as a source of dietary fiber.
Typical levels of pectin in fresh fruits and vegetables are:
In human digestion, pectin binds to cholesterol in the gastrointestinal tract and slows glucose absorption by trapping carbohydrates. Pectin is thus a soluble dietary fiber. In NOD mice pectin has been shown to increase the incidence of autoimmune type 1 diabetes.
A study found that after consumption of fruit the concentration of methanol in the human body increased by as much as an order of magnitude due to the degradation of natural pectin (which is esterified with methanol) in the Large intestine.
Consumption of pectin has been shown to slightly (3–7%) reduce blood LDL cholesterol levels. The effect depends upon the source of pectin; apple and citrus pectins were more effective than orange pulp fibre pectin. The mechanism appears to be an increase of viscosity in the intestinal tract, leading to a reduced absorption of cholesterol from bile or food. In the large intestine and colon, microorganisms degrade pectin and liberate short-chain fatty acids that have a positive prebiotic effect.
The carboxyl groups of polygalacturonic acid are frequently esterified with methanol or acetic acid. The degree of esterification and acetylation varies depending on the source of the pectin and has a decisive impact on its chemical properties. Pectins are therefore classified according to their Methylation (DM) and Acetylation (DA), which represent the ratio of esterified galacturonic acids (methylated or acetylated) to total galacturonic acids. Functionally, three types of pectins are distinguished:
Amidated pectin shows enhanced tolerance to varying calcium concentrations. Thiolated pectin, capable of forming disulfide crosslinks, exhibits superior gelling properties beneficial for pharmaceutical and food applications.
| Section of the pectin Polymer backbone: Poly-α-(1→4)-galacturonic acid. |
| Partially esterified section of the pectin main chain |
| Rhamnogalacturonan: backbone with a “kink” due to incorporated rhamnose |
Homogalacturonan is a linear homopolymer of α-(1 → 4)-linked D-galacturonic acid residues that comprises ∼65 % of pectin. Generally, homogalacturonan comprises D-galacturonic acid residues monomers in long stretches of at least 72 to 100 residues linked together.
Rhamnogalacturonan I is a repeating disaccharide of →4- α-D-GalA-(1, i. e. an alternating copolymer of galacturonic acid and rhammnose, with many O-4 positions containing other neutral sugars, such as Galactose or L-arabinose. The length of the backbone of rhamnogalacturonan I is about 100 to 300 repeating units. Side chains varying by plant sources, such as arabinan, β-(1 → 4)-galactan, type I arabinogalactan (AG-I), and type II arabinogalactan (AG-II) exist. Arabinan consist of α-(1 → 5)-linked L-arabinose backbone, which is usually substituted with α-L-arabinose in different linkages. AG-I is composed out of a β-(1 → 4)-linked D-galactose backbone with α-L-arabinose residues attached to the O-3 position. The terminal galactose of β-(1 → 4) galactan is frequently linked to L-arabinose by α-(1 → 5) glycoside bonds. Type II arabinogalactan is composed of a β-(1 → 3)-linked D-Gal backbone, containing short side chains of α-L-Ara-(1 → 6)- β-D-Gal-(1n. The galactosyl residues of the side chains can be substituted with α-(1 → 3)-linked L-arabinose residues. Type II arabinogalactan is mainly associated with proteins (3–8 %), so called arabinogalactan proteins (AGPs), which are rich in proline/hydroxyproline, alanine, serine, and threonine. D-galacturonic acid residues residues in the backbone of rhamnogalacturonan I may be highly O-acylated on O-2 and/or O-3, but they are not usually methyl esterified. Ferulic acid groups in rhamnogalacturonan I may be ester-linked to O-2 of the arabinose residues and to O-6 of the galactose residues.
Another structural type of pectin is rhamnogalacturonan II (RG-II), which is a less frequent, complex, highly branched polysaccharide. Rhamnogalacturonan II is classified by some authors within the group of substituted galacturonans since the rhamnogalacturonan II backbone is made exclusively of D-galacturonic acid units.
The non-esterified galacturonic acid units can be either free acids (carboxyl groups) or salts with sodium, potassium, or calcium. The salts of partially esterified pectins are called pectinates, if the degree of esterification is below 5 percent the salts are called pectates, the insoluble acid form, pectic acid.
Some plants, such as sugar beet, potatoes and pears, contain pectins with acetylated galacturonic acid in addition to methyl esters. Acetylation prevents gel-formation but increases the stabilising and emulsifying effects of pectin.
Amidated pectin is a modified form of pectin. Here, some of the galacturonic acid is converted with ammonia to carboxylic acid amide. These pectins are more tolerant of varying calcium concentrations that occur in use.
Thiolated pectin exhibits substantially improved gelling properties since this thiomer is able to crosslink via disulfide bond formation. These high gelling properties are advantageous for various pharmaceutical applications and applications in food industry.
Amidated pectins behave like low-ester pectins but need less calcium and are more tolerant of excess calcium. Also, gels from amidated pectin are thermoreversible; they can be heated and after cooling solidify again, whereas conventional pectin-gels will afterwards remain liquid.
While low-methoxy pectins need calcium to form a gel, they can do so at lower soluble solids and higher pH than high-methoxy pectins. Normally low-methoxy pectins form gels with a range of pH from 2.6 to 7.0 and with a soluble solids content between 10 and 70%.
To prepare a pectin-gel, the ingredients are heated, dissolving the pectin. Upon cooling below gelling temperature, a gel starts to form. If gel formation is too strong, syneresis or a granular texture are the result, while weak gelling leads to excessively soft gels.
High-ester pectins set at higher temperatures than low-ester pectins. However, gelling reactions with calcium increase as the degree of esterification falls. Similarly, lower pH-values or higher soluble solids (normally sugars) increase gelling speeds. Suitable pectins can therefore be selected for jams and jellies, or for higher-sugar confectionery jellies.
Industrially, pectinase is widely used in the food industry to clarify fruit juices and wines, enhance juice extraction, and improve the texture of fruit-based products. It is also applied in textile processing, paper production, and wastewater treatment due to its ability to break down plant-derived materials efficiently.
The conventional pectin production method uses hot acidified water extraction, followed by filtration, alcohol precipitation, washing, and drying. This process is robust and established at large scale, but requires significant amounts of mineral acid and organic solvents and may cause partial degradation of the polymer structure (protopectin loses some of its branching).
Alternative “Green chemistry” extraction methods have been developed to address these limitations. Such approaches aim to improve yield and functionality while reducing chemical and energy inputs. Although many of these methods remain at laboratory or pilot scale, they are the subject of ongoing research into sustainable pectin production.
In some countries, pectin is also available as a solution or an extract, or as a blended powder, for home jam making.
The classical application is giving the jelly-like consistency to jams or , which would otherwise be sweet juices. (2025). 9783031460456 ISBN 9783031460456 Pectin also reduces syneresis in jams and marmalades and increases the gel strength of low-calorie jams. For household use, pectin is an ingredient in gelling sugar (also known as "jam sugar") where it is diluted to the right concentration with sugar and some citric acid to adjust pH.
For various food applications, different kinds of pectins can be distinguished by their properties, such as acidity, degree of esterification, relative number of methoxyl groups in the molecules, etc. For instance, the term "high methoxyl" refers to pectins that have a large proportion of the carboxyl groups in the pectin molecule that are esterified with methanol, compared to low methoxyl pectins: (2025). 9783030534202 ISBN 9783030534202 (2011). 9781849732451 ISBN 9781849732451
For conventional jams and marmalades that contain above 60% sugar and soluble fruit solids, high-ester (high methoxyl) pectins are used. With low-ester (low methoxyl) pectins and amidated pectins, less sugar is needed, so that diet products can be made. Water extract of aiyu seeds is traditionally used in Taiwan to make aiyu jelly, where the extract gels without heating due to low-ester pectins from the seeds and the bivalent cations from the water.
Pectin is used in confectionery jellies to give a good gel structure, a clean bite and to confer a good flavour release. Pectin can also be used to stabilise acidic protein drinks, such as drinking yogurt, to improve the mouth-feel and the pulp stability in juice based drinks and as a fat substitute in baked goods.
Typical levels of pectin used as a food additive are between 0.5 and 1.0% – this is about the same amount of pectin as in fresh fruit.
In medicine, pectin increases viscosity and volume of feces so that it is used against constipation and diarrhea. Until 2002, it was one of the main ingredients used in Kaopectate – a medication to combat diarrhea – along with kaolinite. It has been used in gentle heavy metal removal from biological systems. Pectin is also used in throat lozenges as a demulcent.
In cosmetic products, pectin acts as a stabiliser. Pectin is also used in wound healing preparations and speciality medical adhesives, such as colostomy devices.
Sriamornsak revealed that pectin could be used in various oral drug delivery platforms, e.g., controlled release systems, gastro-retentive systems, colon-specific delivery systems and mucoadhesive delivery systems, according to its intoxicity and low cost. It was found that pectin from different sources provides different gelling abilities, due to variations in molecular size and chemical composition. Like other natural polymers, a major problem with pectin is inconsistency in reproducibility between samples, which may result in poor reproducibility in drug delivery characteristics.
In ruminant nutrition, depending on the extent of lignification of the cell wall, pectin is up to 90% digestible by bacterial enzymes. Ruminant nutritionists recommend that the digestibility and energy concentration in forages be improved by increasing pectin concentration in the forage.
In cigars, pectin is considered an excellent substitute for vegetable glue and many cigar smokers and collectors use pectin for repairing damaged tobacco leaves on their cigars.
Yablokov et al., writing in , quote research conducted by the Ukrainian Center of Radiation Medicine and the Belarusian Institute of Radiation Medicine and Endocrinology, concluded, regarding pectin's radioprotective effects, that "adding pectin preparations to the food of inhabitants of the Chernobyl-contaminated regions promotes an effective excretion of incorporated radionuclides" such as cesium-137. The authors reported on the positive results of using pectin food additive preparations in a number of clinical studies conducted on children in severely polluted areas, with up to 50% improvement over control groups. During the Second World War, Allied pilots were provided with maps printed on silk, for navigation in escape and evasion efforts. The printing process at first proved nearly impossible because the several layers of ink immediately ran, blurring outlines and rendering place names illegible until the inventor of the maps, Clayton Hutton, mixed a little pectin with the ink and at once the pectin coagulated the ink and prevented it from running, allowing small topographic features to be clearly visible.
The European Union (EU) has not set a daily intake limit for two types of pectin, known as E440(i) and Amidated Pectin E440(ii). The EU has established purity standards for these additives in the EU Commission Regulation (EU)/231/2012. Pectin can be used as needed in most food categories, a concept referred to as "quantum satis". The European Food Safety Authority (EFSA) conducted a re-evaluation of Pectin E440(i) and Amidated Pectin E440(ii) in 2017. The EFSA concluded that the use of these food additives poses no safety concern for the general population. Furthermore, the agency stated that it is not necessary to establish a numerical value for the Acceptable Daily Intake (ADI).
In the United States, pectin is generally recognised as safe for human consumption.
In the International Numbering System (INS), pectin has the number 440. In Europe, pectins are differentiated into the E440(i) for non-amidated pectins and E440(ii) for amide pectins. There are specifications in all national and international legislation defining its quality and regulating its use.
During the Industrial Revolution, the makers of fruit preserves turned to producers of apple juice to obtain dried apple pomace that was cooked to extract pectin. Later, in the 1920s and 1930s, factories were built that commercially extracted pectin from dried apple pomace, and later citrus peel, in regions that produced apple juice in both the US and Europe.
Pectin was first sold as a liquid extract, but is now most often used as dried powder, which is easier than a liquid to store and handle.
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