View source for Pectin

{{Short description|Structural carbohydrate in the cell walls of land plants and some algae}}
{{Distinguish|Pecten (biology)|Pecten oculi|Pecten (bivalve)}}
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{{Use dmy dates |date=July 2021}}
[[Image:Pectin.jpg|thumb|Commercially produced powder of pectin, extracted from [[citrus fruit]]s]]
'''Pectin''' ({{langx|grc|πηκτικός}} ''{{Transliteration|grc|pēktikós}}'': "congealed" and "curdled") is a [[heteropolysaccharide]], a structural polymer contained in the primary lamella, in the [[middle lamella]], and in the [[cell wall]]s of [[terrestrial plant]]s.<ref name="Liddell">{{LSJ|phktiko/s|πηκτικός|ref}}</ref> 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.<ref name="Braconnot-1825">{{cite journal | vauthors = Braconnot H | date = 1825 | url = https://books.google.com/books?id=1Zg5AAAAcAAJ&pg=PA173 | title = Recherches sur un nouvel acide universellement répandu dans tous les vegetaux | trans-title = Investigations into a new acid spread throughout all plants | journal = Annales de chimie et de physique | issue = 2 | volume = 28 | pages = 173–178 | quote = From page 178:  ... ''je propose le nom ''pectique'', de {{lang|grc|πηχτες}}, coagulum,'' ... (I propose the name ''pectique'', from {{lang|grc|πηχτες}} [pectes], coagulum [coagulated material, clot, curd]) | access-date = 8 January 2016 | archive-date = 7 September 2024 | archive-url = https://web.archive.org/web/20240907194655/https://books.google.com/books?id=1Zg5AAAAcAAJ&pg=PA173#v=onepage&q&f=false | url-status = live }}</ref><ref name="Keppler-2006">{{cite journal | vauthors = Keppler F, Hamilton JT, Brass M, Röckmann T | title = Methane emissions from terrestrial plants under aerobic conditions | journal = Nature | volume = 439 | issue = 7073 | pages = 187–191 | date = January 2006 | pmid = 16407949 | doi = 10.1038/nature04420 | s2cid = 2870347 | bibcode = 2006Natur.439..187K }}</ref>{{Dubious|date=December 2024|reason=Uh, he discovered pectin, not galactic acid.}} Commercially produced pectin is a white-to-light-brown powder, produced from [[citrus fruit]]s for use as an edible [[gelling agent]], especially in [[jam]]s and jellies, dessert fillings, medications, and sweets; as a [[Stabilizer (chemistry)#Food|food stabiliser]] in fruit juices and milk drinks,<ref name="Gerlat-2000">{{cite magazine| vauthors = Gerlat P |date=15 November 2000|title=Beverage Stabilizers|magazine=Food Product Design Magazine|via=Food Ingredients Online - for the food ingredients industry|url=https://www.foodingredientsonline.com/doc/beverage-stabilizers-0001|url-status=live|archive-url=https://web.archive.org/web/20220812141340/https://www.foodingredientsonline.com/doc/beverage-stabilizers-0001|archive-date=12 August 2022|access-date=24 January 2023}}</ref> and as a source of [[dietary fiber]].

== Biology ==
Pectin is composed of complex polysaccharides that are present in the primary cell walls of a plant, and are abundant in the green parts of terrestrial plants.<ref name="Bidhendi-2020">{{cite journal | vauthors = Bidhendi AJ, Chebli Y, Geitmann A | title = Fluorescence visualization of cellulose and pectin in the primary plant cell wall | journal = Journal of Microscopy | volume = 278 | issue = 3 | pages = 164–181 | date = June 2020 | pmid = 32270489 | doi = 10.1111/jmi.12895 | s2cid = 215619998 }}</ref>
Pectin is the principal component of the [[middle lamella]], where it binds cells. Pectin is deposited by exocytosis into the cell wall via vesicles produced in the [[Golgi apparatus]].<ref name="Braidwood-2014">{{cite journal | vauthors = Braidwood L, Breuer C, Sugimoto K | title = My body is a cage: mechanisms and modulation of plant cell growth | journal = The New Phytologist | volume = 201 | issue = 2 | pages = 388–402 | date = January 2014 | pmid = 24033322 | doi = 10.1111/nph.12473 | doi-access = free | bibcode = 2014NewPh.201..388B }}</ref> The amount, structure and chemical composition of pectin is different among plants, within a plant over time, and in various parts of a plant. Pectin is an important cell wall polysaccharide that allows primary cell wall extension and plant growth.<ref name="Bidhendi-2016">{{cite journal | vauthors = Bidhendi AJ, Geitmann A | title = Relating the mechanics of the primary plant cell wall to morphogenesis | journal = Journal of Experimental Botany | volume = 67 | issue = 2 | pages = 449–461 | date = January 2016 | pmid = 26689854 | doi = 10.1093/jxb/erv535 | url = https://academic.oup.com/jxb/article-pdf/67/2/449/9366354/erv535.pdf | access-date = 30 May 2020 | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20180113093611/https://academic.oup.com/jxb/article-pdf/67/2/449/9366354/erv535.pdf | archive-date = 13 January 2018 }}</ref> During fruit [[ripening]], pectin is broken down by the [[enzyme]]s [[pectinase]] and [[pectinesterase]], in which process the fruit becomes softer as the middle lamellae break down and cells become separated from each other.<ref name="Grierson-1986">{{cite journal | vauthors = Grierson D, Maunders MJ, Slater A, Ray J, Bird CR, Schuch W, Holdsworth MJ, Tucker GA, Knapp JE |year=1986|title=Gene expression during tomato ripening|journal=Philosophical Transactions of the Royal Society of London B|volume=314|issue=1166|pages=399–410|doi=10.1098/rstb.1986.0061|bibcode=1986RSPTB.314..399G|doi-access=}}</ref> A similar process of cell separation caused by the breakdown of pectin occurs in the [[abscission zone]] of the [[Petiole (botany)|petiole]]s of [[deciduous]] plants at leaf fall.{{Citation needed|date = March 2015}}

Pectin is a natural part of the human [[wikt:diet|diet]], but does not contribute significantly to [[wikt:nutrition|nutrition]]. The daily intake of pectin from fruits and vegetables can be estimated to be around 5&nbsp;g if approximately 500&nbsp;g of fruits and vegetables are consumed per day.{{Citation needed|date = July 2024}}

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|non-obese diabetic (NOD) mice]] pectin has been shown to increase the incidence of autoimmune type 1 diabetes.<ref name="Toivonen-2014">{{cite journal | vauthors = Toivonen RK, Emani R, Munukka E, Rintala A, Laiho A, Pietilä S, Pursiheimo JP, Soidinsalo P, Linhala M, Eerola E, Huovinen P, Hänninen A | title = Fermentable fibres condition colon microbiota and promote diabetogenesis in NOD mice | journal = Diabetologia | volume = 57 | issue = 10 | pages = 2183–2192 | date = October 2014 | pmid = 25031069 | doi = 10.1007/s00125-014-3325-6 | doi-access = free }}</ref>

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|colon]].<ref name="Lindinger-1997">{{cite journal | vauthors = Lindinger W, Taucher J, Jordan A, Hansel A, Vogel W | title = Endogenous production of methanol after the consumption of fruit | journal = Alcoholism: Clinical and Experimental Research | volume = 21 | issue = 5 | pages = 939–943 | date = August 1997 | pmid = 9267548 | doi = 10.1111/j.1530-0277.1997.tb03862.x }}</ref>

Pectin has been observed to have some function in repairing the DNA of some types of plant seeds, usually desert plants.<ref name="Huang-2004">{{cite journal | vauthors = Huang Z, Gutterman Y, Osborne DJ |title=Value of the mucilaginous pellicle to seeds of the sand-stabilizing desert woody shrub Artemisia sphaerocephala (Asteraceae) |journal=Trees |date=30 July 2004 |volume=18 |issue=6 |pages=669–676 |doi=10.1007/s00468-004-0349-4 |bibcode=2004Trees..18..669H |s2cid=37031814 }}</ref> Pectinaceous surface pellicles, which are rich in pectin, create a mucilage layer that holds in dew that helps the cell repair its DNA.<ref name="Huang-2008">{{cite journal | vauthors = Huang Z, Boubriak I, Osborne DJ, Dong M, Gutterman Y | title = Possible role of pectin-containing mucilage and dew in repairing embryo DNA of seeds adapted to desert conditions | journal = Annals of Botany | volume = 101 | issue = 2 | pages = 277–283 | date = January 2008 | pmid = 17495979 | pmc = 2711012 | doi = 10.1093/aob/mcm089 }}</ref>

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.<ref name="Brouns-2012">{{cite journal | vauthors = Brouns F, Theuwissen E, Adam A, Bell M, Berger A, Mensink RP | title = Cholesterol-lowering properties of different pectin types in mildly hyper-cholesterolemic men and women | journal = European Journal of Clinical Nutrition | volume = 66 | issue = 5 | pages = 591–599 | date = May 2012 | pmid = 22190137 | doi = 10.1038/ejcn.2011.208 | doi-access = free }}</ref> The mechanism appears to be an increase of viscosity in the intestinal tract, leading to a reduced absorption of cholesterol from bile or food.<ref name="Sriamornsak-2003">{{cite journal |url=http://www.journal.su.ac.th/index.php/suij/article/viewFile/48/48 | vauthors = Sriamornsak P |title=Chemistry of Pectin and its Pharmaceutical Uses: A Review |journal=Silpakorn University International Journal |volume=3 |issue=1–2 |year=2003 |page=206 |access-date=23 August 2007 |archive-url=https://web.archive.org/web/20120603005249/http://www.journal.su.ac.th/index.php/suij/article/viewFile/48/48 |archive-date=3 June 2012 |url-status=dead }}</ref> In the large intestine and colon, microorganisms degrade pectin and liberate [[short-chain fatty acid]]s that have a positive [[Prebiotic (nutrition)|prebiotic]] effect.<ref name="Gómez-2014">{{cite journal | vauthors = Gómez B, Gullón B, Remoroza C, Schols HA, Parajó JC, Alonso JL | title = Purification, characterization, and prebiotic properties of pectic oligosaccharides from orange peel wastes | journal = Journal of Agricultural and Food Chemistry | volume = 62 | issue = 40 | pages = 9769–9782 | date = October 2014 | pmid = 25207862 | doi = 10.1021/jf503475b | bibcode = 2014JAFC...62.9769G }}</ref>

==Chemistry==
[[File:Galacturonic acid.png|thumb|[[Galacturonic acid]]]]
Pectins, also known as pectic polysaccharides, are rich in galacturonic acid. Several distinct polysaccharides have been identified and characterised within the pectic group. Homogalacturonans are linear chains of α-(1–4)-linked [[D-Galacturonic acid|<small>D</small>-galacturonic acid]].<ref name="Complex Carbohydrate Research Centre">{{cite web  |url=http://www.ccrc.uga.edu/~mao/galact/gala.htm  |title=Galacturonans  |publisher=Complex Carbohydrate Research Centre, University of Georgia, US  |access-date=23 July 2010 |archive-date=15 August 2010 | archive-url= https://web.archive.org/web/20100815065857/http://www.ccrc.uga.edu/~mao/galact/gala.htm |url-status=dead }}</ref> Substituted galacturonans are characterised by the presence of saccharide appendant residues (such as <small>D</small>-[[xylose]] or <small>D</small>-[[apiose]] in the respective cases of xylogalacturonan and [[apiogalacturonan]]) branching from a backbone of <small>D</small>-galacturonic acid residues.<ref name="Complex Carbohydrate Research Centre"/><ref name="Buchanan-2000">{{cite book | vauthors = Buchanan BB, Gruissem W, Jones RL |title        = Biochemistry and Molecular Biology of Plants |publisher = American Society of Plant Biologists |location = Rockville, MD USA |year = 2000 |url          = https://archive.org/details/biochemistrymole00buch |isbn = 978-0-943088-37-2 |access-date = 23 July 2010 |url-status = dead |url-access = registration |archive-url  = https://web.archive.org/web/20200326153824/https://archive.org/details/biochemistrymole00buch |archive-date = 26 March 2020 }}</ref> Rhamnogalacturonan I pectins (RG-I) contain a backbone of the repeating disaccharide: 4)-α-<small>D</small>-galacturonic acid-(1,2)-α-<small>L</small>-[[rhamnose]]-(1. From many of the rhamnose residues, sidechains of various neutral sugars branch off. The neutral sugars are mainly <small>D</small>-[[galactose]], <small>L</small>-[[arabinose]] and <small>D</small>-xylose, with the types and proportions of neutral sugars varying with the origin of pectin.<ref name="Complex Carbohydrate Research Centre"/><ref name="Buchanan-2000"/><ref name="Ccr-RGI">{{cite web | url = http://www.ccrc.uga.edu/~mao/rg1/rg1.htm | title = RG-I | archive-url = https://web.archive.org/web/20091004031015/http://www.ccrc.uga.edu/~mao/rg1/rg1.htm | archive-date=4 October 2009 | work = Ccrc.uga.edu | access-date = 16 July 2012 }}</ref>

Another structural type of pectin is [[rhamnogalacturonan II]] (RG-II), which is a less frequent, complex, highly branched polysaccharide.<ref name="Ccrc-RGII">{{cite web | url = http://www.ccrc.uga.edu/~mao/rg2/intro.htm | title = Rhamnogalacturonan II | work = www.ccrc.uga.edu | archive-url = https://web.archive.org/web/20091003140059/http://www.ccrc.uga.edu/~mao/rg2/intro.htm | archive-date = 3 October 2009 | access-date = 16 July 2012 }}</ref> Rhamnogalacturonan II is classified by some authors within the group of substituted galacturonans since the rhamnogalacturonan II backbone is made exclusively of <small>D</small>-galacturonic acid units.<ref name="Buchanan-2000"/>

The [[molecular weight]] of isolated pectine greatly varies by the source and the method of isolation.<ref>{{cite journal | vauthors = Singaram A, Guruchandran S, Ganesan N | title = Review on functionalized pectin films for active food packaging | journal = Packaging Technology and Science | volume = 37 | issue = 4 | pages = 237–262 | date = 2024 | doi = 10.1002/pts.2793 }}</ref> Values have been reported as low as 28 kDa for apple pomace <ref>{{cite journal | vauthors = Wang X, Chen Q, Lü X | title = Pectin extracted from apple pomace and citrus peel by subcritical water | journal = Food Hydrocoll. | date = 2014 | volume = 38 | pages = 129–137 | doi=10.1016/J.FOODHYD.2013.12.003}}</ref> up to 753 kDa for  sweet potato peels.<ref>{{cite journal | vauthors = Arachchige M, Mu T, Ma M | title = Structural, physicochemical and emulsifying properties of sweet potato pectin treated by high hydrostatic pressure and/or pectinase: a comparative study | journal=J Sci Food Agric | date = 2020 | volume = 100 | issue = 13 | pages = 4911–4920 | doi = 10.1007/s11696-018-0500-0 | pmid = 32483850 }}</ref>

In nature, around 80 percent of [[carboxyl group]]s of galacturonic acid are [[ester]]ified with [[methanol]]. This proportion is decreased to a varying degree during pectin extraction. Pectins are classified as high- versus low-methoxy pectins (short HM-pectins versus LM-pectins), with more or less than half of all the galacturonic acid esterified.<ref name="Liang-2012">{{cite journal | vauthors = Liang RH, Chen J, Liu W, Liu CM, Yu W, Yuan M, Zhou XQ | title = Extraction, characterization and spontaneous gel-forming property of pectin from creeping fig (Ficus pumila Linn.) seeds | journal = Carbohydrate Polymers | volume = 87 | issue = 1 | pages = 76–83 | date = January 2012 | pmid = 34663033 | doi = 10.1016/j.carbpol.2011.07.013 }}</ref> The ratio of esterified to non-esterified galacturonic acid determines the behaviour of pectin in food applications – HM-pectins can form a gel under acidic conditions in the presence of high sugar concentrations, while LM-pectins form gels by interaction with divalent cations, particularly [[Calcium in biology|Ca<sup>2+</sup>]], according to the idealized 'egg box' model, in which ionic bridges are formed between calcium ions and the ionised carboxyl groups of the galacturonic acid.<ref name="Durand-1990">{{cite journal | vauthors = Durand D, Bertrand C, Clark AH, Lips A | title = Calcium-induced gelation of low methoxy pectin solutions--thermodynamic and rheological considerations | journal = International Journal of Biological Macromolecules | volume = 12 | issue = 1 | pages = 14–18 | date = February 1990 | pmid = 2083236 | doi = 10.1016/0141-8130(90)90076-M }}</ref><ref name="Migliori-2010">{{cite journal | vauthors = Migliori M, Gabriele D, Checchetti A, Battipede B | year = 2010| title = Compatibility analysis of pectin at different esterification degree from intrinsic viscosity data of diluted ternary solutions | journal = Reactive and Functional Polymers | volume = 70 | issue = 10| pages = 863–867 | doi = 10.1016/j.reactfunctpolym.2010.07.011 | bibcode = 2010RFPol..70..863M}}</ref><ref name="Liang-2012" />

In high-methoxy pectins at soluble solids content above 60% and a pH value between 2.8 and 3.6, [[hydrogen bonds]] and [[hydrophobic interactions]] bind the individual pectin chains together. These bonds form as water is bound by sugar and forces pectin strands to stick together. These form a three-dimensional molecular net that creates the macromolecular gel. The gelling-mechanism is called a low-water-activity gel or sugar-acid-pectin gel.{{Citation needed|date=July 2018}}

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%.{{Citation needed|date=July 2018}}

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.{{Citation needed|date=July 2018}}

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.{{Citation needed|date=July 2018}}

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.<ref name="Belitz-2004">{{cite book | vauthors = Belitz HD, Grosch W, Schieberle P | title = Food Chemistry | publisher = Springer | location = Berlin | date = April 2004 }}</ref>

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.<ref name="Majzoob-2006">{{cite journal | vauthors = Majzoob S, Atyabi F, Dorkoosh F, Kafedjiiski K, Loretz B, Bernkop-Schnürch A | title = Pectin-cysteine conjugate: synthesis and in-vitro evaluation of its potential for drug delivery | journal = The Journal of Pharmacy and Pharmacology | volume = 58 | issue = 12 | pages = 1601–1610 | date = December 2006 | pmid = 17331323 | doi = 10.1211/jpp.58.12.0006 | s2cid = 24127477 | doi-access = free }}</ref><ref name="Perera-2010">{{cite journal | vauthors = Perera G, Hombach J, Bernkop-Schnürch A | title = Hydrophobic thiolation of pectin with 4-aminothiophenol: synthesis and in vitro characterization | journal = AAPS PharmSciTech | volume = 11 | issue = 1 | pages = 174–180 | date = March 2010 | pmid = 20101485 | pmc = 2850493 | doi = 10.1208/s12249-009-9370-7 | s2cid = 25025639 }}</ref><ref name="Chen-2023">{{cite journal | vauthors = Chen J, Cui Y, Zhang S, Ma Y, Yang F | title = Compound treatment of thiolated citrus high-methoxyl pectin and sodium phosphate dibasic anhydrous improved gluten network structure | journal = Food Chemistry | volume = 404 | issue = Pt B | pages = 134770 | date = March 2023 | pmid = 36332584 | doi = 10.1016/j.foodchem.2022.134770 | s2cid = 253214393 }}</ref>

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 (chemistry)|syneresis]] or a granular texture are the result, while weak gelling leads to excessively soft gels.{{Citation needed|date=July 2018}}

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.{{Citation needed|date=July 2018}}

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.{{Citation needed|date=July 2018}}

== Sources and production ==
Pears, apples, guavas, [[quince]], plums, gooseberries, and oranges and other citrus fruits contain large amounts of pectin, while soft fruits, like cherries, grapes, and strawberries, contain small amounts of pectin.{{Citation needed|date=July 2018}}

Typical levels of pectin in fresh fruits and vegetables are:
* [[Apples]], 1–1.5%
* [[Apricot]]s, 1%
* [[Cherries]], 0.4%
* [[Orange (fruit)|Oranges]], 0.5–3.5%
* Carrots 1.4%
* [[Citrus]] [[Peel (fruit)|peels]], 30%
* [[Rose hips]], 15%<ref name="Wichtl-2004">{{cite book |vauthors=Wichtl M |chapter=Monograph: Rosae Pseudofrutus (Rose Hips) |chapter-url=https://books.google.com/books?id=7PRyMWo5e28C&dq=analysis+pectin+rose+hip+15%25&pg=PA520 |title=Herbal Drugs and Phytopharmaceuticals: a handbook for practice on a scientific basis |date=January 2004 |publisher=Medpharm; CRC Press |location=Stuttgart : Boca Raton, FL |isbn=978-0-8493-1961-7 |edition=3rd expanded and completely rev. |page=520 |access-date=14 March 2023 |archive-date=12 October 2023 |archive-url=https://web.archive.org/web/20231012173031/https://books.google.com/books?id=7PRyMWo5e28C&dq=analysis+pectin+rose+hip+15%&pg=PA520 |url-status=live }}</ref>
The main raw materials for pectin production are dried citrus peels or apple [[pomace]], both by-products of juice production. Pomace from sugar beets is also used to a small extent.{{Citation needed|date=July 2018}}

From these materials, pectin is extracted by adding hot dilute acid at pH values from 1.5 to 3.5. During several hours of extraction, the protopectin loses some of its branching and chain length and goes into solution. After filtering, the extract is concentrated in a vacuum and the pectin is then [[ethanol precipitation|precipitated]] by adding ethanol or isopropanol. An old technique of precipitating pectin with aluminium salts is no longer used (apart from alcohols and polyvalent cations, pectin also precipitates with proteins and detergents).{{Citation needed|date=July 2018}}

Alcohol-precipitated pectin is then separated, washed, and dried. Treating the initial pectin with dilute acid leads to low-esterified pectins. When this process includes ammonium hydroxide (NH<sub>3</sub>(aq)), amidated pectins are obtained. After drying and milling, pectin is usually standardised{{clarify|date=November 2017}} with sugar, and sometimes calcium salts or organic acids, to optimise performance in a particular application.<ref name="Eisenbrand-2006">G. Eisenbrand, P. Schreier; RÖMPP Lexikon Lebensmittelchemie; Thieme, Stuttgart; Mai 2006</ref>

==Uses==
The main use for pectin is as a [[gelling agent]], thickening agent and stabiliser in food.<ref name="Han-2020">{{cite web|url=https://foodadditives.net/thickeners/pectin/| vauthors = Han J |title=What is Pectin (E440)? Sources, Types, Uses, and Benefits|date=13 June 2020|access-date=7 April 2024|archive-date=27 September 2023|archive-url=https://web.archive.org/web/20230927090934/https://foodadditives.net/thickeners/pectin/|url-status=live}}</ref>

In some countries, pectin is also available as a solution or an extract, or as a blended powder, for home jam making.{{citation needed|date=April 2024}}

The classical application is giving the jelly-like consistency to jams or [[marmalade]]s, which would otherwise be sweet juices.<ref name="Surolia-2024">{{cite book|doi=10.1007/978-3-031-46046-3_13 |chapter=Pectin—Structure, Specification, Production, Applications and various Emerging Sources: A Review |title=Sustainable Food Systems (Volume II) |series=World Sustainability Series |date=2024 |pages=267–282 |isbn=978-3-031-46045-6 | vauthors = Surolia R, Singh A }}</ref> Pectin also reduces [[syneresis (chemistry)|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.{{citation needed|date=April 2024}}

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:<ref name="Surolia-2024"/><ref name="Kontogiorgos V-2020">{{cite book|doi=10.1007/978-3-030-53421-9 |title=Pectin: Technological and Physiological Properties |date=2020 |isbn=978-3-030-53420-2 | veditors = Kontogiorgos V }}</ref><ref name="Endress-2011">{{cite book|doi=10.1039/9781849733519-00210|date=17 August 2011 |chapter=Pectins: Production, Properties and Applications |title=Renewable Resources for Functional Polymers and Biomaterials |pages=210–260 |isbn=978-1-84973-245-1 | vauthors = Endress H }}</ref>
* high methoxyl pectins are defined as those with a degree of esterification equal to or above 50, are typically used in traditional jam and jelly making;<ref name="UniPECTINE">{{cite web|url=https://www.cargill.com/doc/1432231523066/cargill-emea-unipectine-brochure.pdf|title=UniPECTINE|access-date=7 April 2024|archive-date=7 April 2024|archive-url=https://web.archive.org/web/20240407124532/https://www.cargill.com/doc/1432231523066/cargill-emea-unipectine-brochure.pdf|url-status=live}}</ref><ref name="Yang-2020">{{cite book|doi=10.1007/978-3-030-53421-9_1|isbn=978-3-030-53421-9|date=2 October 2020 |chapter=Biosynthesis, Localisation, and Function of Pectins in Plants |title=Pectin: Technological and Physiological Properties |pages=1–15 | vauthors = Yang Y, Anderson CT }}</ref><ref name="Han-2020"/> such pectins require high sugar concentrations and acidic conditions to form gels, and provide a smooth texture and suitable to be used in bakery fillings and confectionery applications;<ref name="Han-2020"/><ref name="Endress-2011"/><ref name="Sultana-2023">{{cite journal |vauthors=Sultana N |title=Biological Properties and Biomedical Applications of Pectin and Pectin-Based Composites: A Review |journal=Molecules |volume=28 |issue=24 |date=December 2023 |page=7974 |pmid=38138464 |pmc=10745545 |doi=10.3390/molecules28247974 |doi-access=free}}</ref>
* low methoxyl pectins have a degree of esterification of less than 50,<ref name="Endress-2011"/><ref name="Han-2020"/> can be either amidated or non-amidated: the percentage level of substitution of the amide group, defined as the degree of amidation, defines the efficacy of a pectin;<ref name="Han-2020"/> low methoxyl pectins can provide a range of textures and rheological properties, depending on the calcium concentration and the calcium reactivity of the pectin chosen<ref name="Said-2023">{{cite journal |vauthors=Said NS, Olawuyi IF, Lee WY |title=Pectin Hydrogels: Gel-Forming Behaviors, Mechanisms, and Food Applications |journal=Gels |volume=9 |issue=9 |date=September 2023 |page=732 |pmid=37754413 |pmc=10530747 |doi=10.3390/gels9090732 |doi-access=free}}</ref>—amidated low methoxyl pectins are generally thermoreversible, meaning they can form gels that can melt and reform, whereas non-amidated low methoxyl pectins can form thermostable gels that withstand high temperatures;<ref name="Said-2023" /> these properties make low methoxyl pectins suitable for low sugar and sugar-free applications, dairy products, and stabilizing acidic protein drinks.<ref name="UniPECTINE"/><ref name="Kontogiorgos V-2020"/><ref name="Han-2020"/>

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 [[Ficus pumila var. awkeotsang|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.<ref name="Liang-2012"/>

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.<ref name="UniPECTINE"/><ref name="May-1990" >{{cite journal | vauthors = May CD | year = 1990 | title = Industrial pectins: Sources, production and applications | journal = Carbohydrate Polymers | volume = 12 | issue = 1| pages = 79–99 | doi = 10.1016/0144-8617(90)90105-2 }}</ref>

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.<ref name="Thakur-1997">{{cite journal | vauthors = Thakur BR, Singh RK, Handa AK | title = Chemistry and uses of pectin--a review | journal = Critical Reviews in Food Science and Nutrition | volume = 37 | issue = 1 | pages = 47–73 | date = February 1997 | pmid = 9067088 | doi = 10.1080/10408399709527767 }}</ref>

In medicine, pectin increases [[viscosity]] and volume of [[feces|stool]] 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.<ref name="Zhao-2008">{{cite journal | vauthors = Zhao ZY, Liang L, Fan X, Yu Z, Hotchkiss AT, Wilk BJ, Eliaz I | title = The role of modified citrus pectin as an effective chelator of lead in children hospitalized with toxic lead levels | journal = Alternative Therapies in Health and Medicine | volume = 14 | issue = 4 | pages = 34–38 | date = 2008 | pmid = 18616067 | doi = | url = }}</ref> Pectin is also used in throat lozenges as a [[demulcent]].{{Citation needed|date=July 2018}}

In cosmetic products, pectin acts as a stabiliser. Pectin is also used in wound healing preparations and speciality medical adhesives, such as [[colostomy]] devices.{{Citation needed|date=July 2018}}

Sriamornsak<ref name="Sriamornsak-2011">{{cite journal | vauthors = Sriamornsak P | title = Application of pectin in oral drug delivery | journal = Expert Opinion on Drug Delivery | volume = 8 | issue = 8 | pages = 1009–1023 | date = August 2011 | pmid = 21564000 | doi = 10.1517/17425247.2011.584867 | s2cid = 25595142 }}</ref> 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.{{Citation needed|date=July 2018}}

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.{{Citation needed|date = July 2024}}

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.{{Citation needed|date = July 2024}}

Yablokov ''et al.'', writing in ''[[Chernobyl: Consequences of the Catastrophe for People and the Environment]]'', 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.<ref name="Nesterenko-2009">{{cite journal | vauthors = Nesterenko VB, Nesterenko AV | title = 13. Decorporation of Chernobyl radionuclides | journal = Annals of the New York Academy of Sciences | volume = 1181 | issue = 1| pages = 303–310 | date = November 2009 | pmid = 20002057 | doi = 10.1111/j.1749-6632.2009.04838.x | bibcode = 2009NYASA1181..303N | url = https://books.google.com/books?id=g34tNlYOB3AC&pg=PA304 | isbn = 978-1-57331-757-3 | url-access = subscription }}</ref>
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, [[Christopher Hutton|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.<ref name="www.escape-maps.com">{{Cite web|url=http://www.escape-maps.com/escape_maps/history_of_wwii_british_cloth_escape_maps.htm#_edn24|title=history of wwii british cloth escape maps|website=www.escape-maps.com|access-date=29 June 2019|archive-date=25 June 2019|archive-url=https://web.archive.org/web/20190625005526/http://www.escape-maps.com/escape_maps/history_of_wwii_british_cloth_escape_maps.htm#_edn24|url-status=live}}</ref>

==Legal status==
At [[the Joint FAO/WHO Expert Committee Report on Food Additives]] and in the [[European Union]], no numerical [[acceptable daily intake]] (ADI) has been set, as pectin is considered safe.<ref name="FAO/WHO Expert Committee on Food Additives">{{cite report | vauthors = ((Joint FAO/WHO Expert Committee on Food Additives)) | url = http://www.who.int/ipcs/food/jecfa/en/ | title = Chemical Risks in Food | work = Who.int. | archive-url = https://web.archive.org/web/20040708001807/http://www.who.int/ipcs/food/jecfa/en/ | access-date = 16 July 2012 | archive-date = 8 July 2004 }}</ref>

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".<ref name="Commission Regulation">{{cite web | url=https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:32011R1130 | title=Commission Regulation (EU) No 1130/2011 of 11 November 2011 amending Annex III to Regulation (EC) No 1333/2008 of the European Parliament and of the Council on food additives by establishing a Union list of food additives approved for use in food additives, food enzymes, food flavourings and nutrients Text with EEA relevance | access-date=7 April 2024 | archive-date=11 December 2023 | archive-url=https://web.archive.org/web/20231211105626/http://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32011R1130 | url-status=live }}</ref> 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).<ref name="Mortensen-2017">{{cite journal | doi=10.2903/j.efsa.2017.4866 | title=Re-evaluation of pectin (E 440i) and amidated pectin (E 440ii) as food additives | journal=EFSA Journal | volume=15 | issue=7 | pages=e04866 | pmid=32625540 | pmc=7010145 | vauthors=Mortensen A, Aguilar F, Crebelli R, Di Domenico A, Dusemund B, Frutos MJ, Galtier P, Gott D, Gundert-Remy U, Lambré C, Leblanc J, Lindtner O, Moldeus P, Mosesso P, Oskarsson A, Parent-Massin D, Stankovic I, Waalkens-Berendsen I, Wright M, Younes M, Tobback P, Ioannidou S, Tasiopoulou S, Woutersen RA, Woutersen RA | url=https://www.efsa.europa.eu/en/efsajournal/pub/4866 | date=6 July 2017 | access-date=7 April 2024 | archive-date=21 January 2022 | archive-url=https://web.archive.org/web/20220121075034/https://www.efsa.europa.eu/en/efsajournal/pub/4866 | url-status=live }}</ref><ref name="EFSA Panel on Food Additives and Flavourings (FAF)-2021">{{cite journal | doi=10.2903/j.efsa.2021.6387 | url=https://www.efsa.europa.eu/en/efsajournal/pub/6387 | title=Opinion on the re-evaluation of pectin (E 440i) and amidated pectin (E 440ii) as food additives in foods for infants below 16 weeks of age and follow-up of their re-evaluation as food additives for uses in foods for all population groups &#124; EFSA | date=29 January 2021 | pmid=33537069 | author1=EFSA Panel on Food Additives and Flavourings (FAF) | journal=EFSA Journal | volume=19 | issue=1 | pages=e06387 | pmc=7845505 | hdl=11368/2979399 | access-date=7 April 2024 | archive-date=21 January 2022 | archive-url=https://web.archive.org/web/20220121064700/https://www.efsa.europa.eu/en/efsajournal/pub/6387 | url-status=live }}</ref>

In the United States, pectin is [[generally recognised as safe]] for human consumption.{{citation needed|date=April 2024}}

In the [[International Numbering System]] (INS), pectin has the number 440. In Europe, pectins are differentiated into the [[E number]]s E440(i) for non-amidated pectins and E440(ii) for [[amide|amidated]] pectins. There are specifications in all national and international legislation defining its quality and regulating its use.{{citation needed|date=April 2024}}

==History==
Pectin was first isolated and described in 1825 by [[Henri Braconnot]], though the action of pectin to make jams and marmalades was known long before. To obtain well-set jams from fruits that had little or only poor quality pectin, pectin-rich fruits or their extracts were mixed into the recipe.{{Citation needed|date = July 2024}}

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.{{Citation needed|date = July 2024}}

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.<ref name="International Pectin Producers Association">{{cite web | url = http://www.ippa.info | title = International Pectin Producers Association | archive-url = https://web.archive.org/web/20220211200148/https://ippa.info/ | archive-date=11 February 2022 | access-date = 13 June 2007 }}</ref>

==See also==
{{Portal|Food}}
* [[Fruit snacks]]

== References ==
{{Reflist|30em}}

==External links==
* [http://www.codexalimentarius.net/gsfaonline/additives/details.html?id=21 Codex General Standard for Food Additives (GSFA) Online Database; A list of permitted uses of pectin, further link to the JECFA (...) specification of pectin.]
* [https://web.archive.org/web/20080309150734/http://eur-lex.europa.eu/LexUriServ/site/en/consleg/1995/L/01995L0002-20031120-en.pdf European parliament and council directive No 95/2/EC of 20 February 1995 on food additives other than colours and sweeteners; EU-Directive that lists the foods, pectin may be used in.] Note: The link points to a "consleg"-version of the directive, that may not include the very latest changes. The Directive will be replaced by a new Regulation for food additives in the next few years.
* [http://www.certohealth.co.uk/health.html Certo Health: Information on reported health benefits of apple pectin, (UK).]

{{Apples|state=collapsed}}
{{Carbohydrates}}
{{Antidiarrheals, intestinal anti-inflammatory and anti-infective agents}}
{{Authority control}}

[[Category:Polysaccharides]]
[[Category:Food additives]]
[[Category:Food science]]
[[Category:Edible thickening agents]]
[[Category:Demulcents]]
[[Category:Food stabilizers]]
[[Category:E-number additives]]