Pectin | Uses, Suppliers, and Specifications
Pectin is a complex, polydisperse polysaccharide obtained from the rind of citrus fruits or from apple pomace. It consists chiefly of partially methoxylated polygalacturonic acids. Pharmaceutical-grade pectin is supplied as a coarse or fine, yellowish-white, odourless powder that has a mucilaginous taste.
Synonyms and Trade Names: Pectin; Citrus pectin; Methyl pectin; Methyl Pectinate; Pectinic acid; E440; Genu® Pectin USP 100; UniPECTINE®; GRINDSTED® Pectin
Uses and Applications: Adsorbent; Emulsifying Agent; Gelling Agent; Thickening Agent; and Stabilising Agent
Pectin is a large molecular weight carbohydrate material that is widely distributed in terrestrial plants, where it functions in combination with cellulose as an intercellular scaffold material. It was discovered in the early 19th century as a gelling agent and has been widely used in the food industry since then. The commercial material is currently obtained from the dilute acid extract of the inner portion of the rind of citrus fruits or from apple pomace or sugar beet. It is supplied as a coarse or fine, yellowish-white, odourless powder that has a mucilaginous taste.
Pectin is chemically classified as a polyuronide. It is, however, a complex, polydisperse and polymolecular polysaccharide whose composition varies with the source and conditions employed during manufacture. Thus, despite being known for more than 200 years, the exact composition and structure of pectin still remain unknown due to the fact that it can change during isolation from plants, storage or processing.
Nevertheless, Pectin is presently thought to consist of a linear polysaccharide made up of the α-D-galacturonic acid (pKa 3.5). Individual galacturonic acid residues are linked via the α-(1,4) configuration. Some of the carboxylic acid groups are esterified with methanol. This is illustrated below:
Secondary hydroxyl groups may also be partially esterified with acetate groups depending on the origin (plant source) of the Pectin. Sugar side chains (β-(1,4)-D-galactans, α-(1,5) -L-arabenes) may also be present in the structure of Pectin. Rhamnose residues, linked with galacturonic acid residues at the 1- and 2- positions, are fused into the material’s backbone. This makes the Pectin molecule stretched (with a characteristic kink). It has a molecular weight that is between 30 and 300 kDa.
The raw materials used in Pectin production are by-products of other operations (e.g fruit juice or sugar extraction). The extracted material is purified, filtered and dried either by drum drying or spray drying. The standard production process can be modified and through controlled de-esterification, to yield Pectin grades with different degrees of esterification and polymerisation. Furthermore, amidated Pectin grades can also be obtained by amidating standard Pectin with ammonia.
When processing commercial-grade Pectin, the majority of the neutral side chains are eliminated. For this reason, 70% of commercial Pectin consists of galacturonic acid, of which up to 75% of the galacturonan groups are methyl esterified. On this basis, Pectin can be divided into two main classes:
- High-esterified Pectin (HM Pectin) consists of a methoxyl level of >7% and a degree of esterification >50% (typically 55-75%)
- Low-esterified Pectin (LM Pectin) consists of a methoxyl level of >7% and a degree of esterification <50% (typically, 255-45%)
The LM pectin can be amidated (by reacting Pectin with ammonia) which converts some of the C6 methyl ester groups into amide groups. Amidated LM Pectin consists of a 30% degree of esterification and a 20% degree of amidation.
For consistent performance (for instance, gel strength and mouthfeel), some grades of Pectin are supplied as standardised grades (with sugars and buffers).
Generally, Pectin is water-soluble or yields colloidal dispersions. It is not soluble in alcohol and the majority of organic solvents. Concentrated solutions exhibit non-Newtonian rheological behaviour (viscosity increases as the rate of shear is increased). This can make the preparation of solutions difficult without the use of very high shear rates.
Chemical Structure & Identifiers
|CAS Registration Number||[9000-65-5]|
|Molecular weight||Pectin contains from a few hundred to about 1000 saccharide units; corresponding to average molecular weights from about 50,000 to 150,000 . Large differences may exist between grades and between molecules within a sample and estimates may differ between methods of measurement.|
|UNII Code (FDA)||89NA02M4RX|
Pectin is an approved excipient. It is listed in the USP-NF, is GRAS listed and is included in the US FDA Inactive Ingredients Database (for dental paste, oral powders and topical pastes). In the United States and Europe, Pectin is accepted for use as a food additive (under the number E 440 in the EU).
|Physical form||Solid, powder|
|Appearance||Coarse or fine, yellowish-white and odourless powder|
|Solubility||Pectins are soluble in pure water. Monovalent cation salts of pectinic and pectic acids are usually soluble in water; di- and trivalent cations salts are weakly soluble or insoluble. Dry powdered pectin, when added to water, has a tendency to hydrate very rapidly, forming clumps. Clumps consist of semidry packets of pectin contained in an envelope of highly hydrated outer coating. Clump formation can be prevented by dry mixing pectin powder with water-soluble carrier material or by the use of pectin having improved dispersibility|
|Viscosity/rheology||Dilute pectin solutions are Newtonian but at a moderate concentration, and exhibit non-Newtonian, pseudoplastic behaviour. Viscosity, solubility, and gelation are generally related. For example, factors that increase gel strength will increase the tendency to gel, decrease solubility, and increase viscosity, and vice versa.|
|Behaviour in solution||properties of pectins are a function of their structure, which is that of a linear polyanion. As such, monovalent cation salts of pectins are highly ionised in solution, and the distribution of ionic charges along the molecule tends to keep it in an extended form by reason of coulombic repulsion|
|pKa||Apparent pK values vary with the DE of the pectin; a 65% DE pectin has an apparent pK of 3.55, while a 0% DE pectic acid has an apparent pK of 4.10. However, pectins with increasingly greater degrees of methylation will gel at higher pH, because they have fewer carboxylate anions at any given pH. In general, maximum stability is found at pH 4.|
|Methoxy groups %||≤6.7%|
|Sugar and organic acid (mg/25ml)||≤16%|
|Loss on drying||≤10%|
|Methanol, Ethanol and Isopropanol||≤1%|
Total Anaerobic Organisms
Molds and Yeasts
|Degree of esterification||specified|
Key: n/a Specification is not listed
*All claims with respect to conformity are subject to our Terms and Conditions. No express or implied warranty is made for specific properties or fitness for any particular application or purpose.
Applications in Pharmaceutical Formulations or Technology
Pectin is used mainly in the food sector and much less so in the pharmaceutical industry as an adsorbent, emulsifying agent, gelling agent, thickening agent and stabilizing agent. It is also used as a bulk-forming agent and is present in multi-ingredient therapeutic preparations used to manage diarrhoea, constipation, and obesity.
In the food sector, Pectin is used to control moisture content in products, helping impart texture. HM Pectin gives structure, stability and texture to low pH jams, jellies and confectionery. It is also used as a non-gelling stabiliser in acidified dairy or non-diary drinks and fruit beverages. In baked goods, HM pectin improves volume and moisture retention, giving products softness and freeze-thaw stability. LM Pectin is used to thicken fruit-based products enabling them to be pumped easily.
In the pharmaceutical field, Pectin has been used in a colon-biodegradable matrix drug delivery system with a pH-sensitive polymeric coating, as a method for retarding the onset of drug release, overcoming the problems of pectin solubility in the upper GI tract. Pectins have been used as a component in the preparation of mixed polymer microsphere systems with the intention of producing controlled drug release.
Pectin is a film former and has been used in film-coating formulations containing Chitosan and Hypromellose to achieve biphasic drug-release properties of film-coated tablets. It has been shown that chitosan acts as a crosslinking agent for concentrated Pectin solutions.
LM Pectins form thermoreversible gels in the presence of calcium ions and at low pH (3 – 4.5) whereas high methoxyl pectins rapidly form thermally irreversible gels in the presence of sufficient (for example, 65% by weight) sugars such as Sucrose and at low pH (< 3.5); the lower the methoxyl content, the slower the set. The degree of esterification can be (incompletely) reduced using commercial pectin methylesterase, leading to a higher viscosity and firmer gelling in the presence of Ca2+ ions. Highly acetylated Pectin from sugar beet is reported to gel poorly but has considerable emulsification ability due to its more hydrophobic nature.
Pectin can be used at concentrations of 1-2% to produce Gelatin-free dietary gummies. Pectin gummies are reportedly superior with respect to flavour release and bite characteristics. Pectin gummies are also less chewy and possess a softer and more masticable texture which is highly favoured by consumers.
As with other viscous polyanions such as Carrageenan, Pectin may be protective towards milk casein colloids, enhancing the properties (foam stability, solubility, gelation, and emulsification) of whey proteins while utilizing them as a source of calcium. Thus, mixtures of casein and pectin can be used to formulate acidified milk drinks, emulsions, edible packaging film and fat replacements.
There is increasing evidence that dietary Pectin may have some health benefits beyond its role as a useful dietary fibre. Small pectin fragments have a positive effect as an anti-cancer agent as they bind to and inhibit the various actions of the pro-metastatic protein galectin-3.
However, due to its structural complexity, the processing of pectins may result in complex and somewhat unpredictable effects on texture, viscosity and gel formation. Advances in its production, the role it plays as a nutraceutical, its possible prebiotic potential and its use as a delivery vehicle for probiotics have been reported.
Safety and Precautions
Pectin is a soluble dietary fibre and a normal constituent of the human diet. However, it does not contribute significantly to nutritional requirements. It has been estimated that the daily intake of Pectin from fruits and vegetables is around 5g on the assumption of 500g consumption of fruits and vegetables. Upon ingestion, Pectin is not digested by human enzymes and is instead acted upon by gut microflora where it is subsequently degraded.
Pectin is currently regarded as a safe additive and has been assigned a daily intake (ADI) of not specified by FAO/WHO and the European Union. The United States FDA has assigned Pectin GRAS status. In the EU, both amidated and non-amidated Pectin are assigned E440 even though they are legislatively distinguished.
Stability and Storage Conditions
Pectin is a nonreactive and stable excipient although moderately hygroscopic. The assigned shelf life is 24-36 months if stored in a cool dry place. Powdered HM-pectins are reported to slowly lose their ability to form gels if stored under humid or warm conditions while LM-pectins are more stable and functionality loss is not significant after one year of storage at room temperature.
When handling Pectin, observe established SHEQ protocols appropriate to the circumstances and quantity of material handled. When pectin is heated to decomposition, acrid smoke and irritating fumes are emitted. The use of appropriate PPE is highly recommended.
Sustainability and Environmental Impact
A sustainability score for Pectin has not been provided.
Manufacturers & Suppliers
Additional Resources (Downloads)
References and Literature Used
 O. Munjeri, J.H. Collett, J.T. Fell, Hydrogel beads based on amidated pectins for colon-specific drug delivery: the role of chitosan in modifying drug release, Journal of Controlled Release, 46 (1997) 273-278.
 H. Kim, G. Venkatesh, R. Fassihi, Compactibility characterization of granular pectin for tableting operation using a compaction simulator, International Journal of Pharmaceutics, 161 (1998) 149-159.
 G.S. Macleod, J.T. Fell, J.H. Collett, An in vitro investigation into the potential for bimodal drug release from pectin/chitosan/HPMC-coated tablets, International Journal of Pharmaceutics, 188 (1999) 11-18.
 S.A. Sande, Pectin-based oral drug delivery to the colon, Expert Opinion on Drug Delivery, 2 (2005) 441-450.
 L. Salbu, A. Bauer-Brandl, I. Tho, Direct compression behaviour of low-and high-methoxylated pectins, AAPS PharmSciTech, 11 (2010) 18-26.
 L. Salbu, A. Bauer-Brandl, G. Alderborn, I. Tho, Effect of degree of methoxylation and particle size on compression properties and compactibility of pectin powders, Pharmaceutical Development and Technology, 17 (2012) 333-343.
 P. Chomto, J. Nunthanid, Physicochemical and powder characteristics of various citrus pectins and their application for oral pharmaceutical tablets, Carbohydrate Polymers, 174 (2017) 25-31.
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