Written by: Amanda Golebiewski
If you have ever made jams or jellies at home, you have used pectin. As an R&D Technologist at a food manufacturing company, I use pectin quite frequently in baking jams, dessert syrups, and more. Pectin is very versatile; it can create gels of varying strength ranging from a pourable sauce to a stiff jelly. Pectin’s usage extends further than the food industry. It can be processed into a fiber supplement or medicinal filler/stabilizer as well.
History
The word, pectin, originates from the Greek word, pektos, which means firm and congealed. Pectin was discovered by a French chemist/pharmacist named Henri Braconnot in 1825. It was first produced commercially in both the United States and Europe during the early 20th century.
Processing/Types
Pectin is a high molecular-weight carbohydrate called a heteropolysaccharide. In terrestrial plants, pectin is what gives the plant cells structure and rigidity. Without it, fruits and vegetables would be unable to grow into their distinct shapes. It is found in middle lamella of plant tissues and the primary cell wall.
All terrestrial plants have varying amounts of pectin. Extraction from dried citrus peels or apple pomace are the most common sources for commercial production. These fruits have the greatest amount of pectin by weight, their pectin is the most easily isolatable, and it is high quality. The fruit material is exposed to a mild acid for extraction. It causes hydrolytic depolymerization and methyl ester hydrolysis to occur. This solution can then be concentrated and the pectin precipitated using ethanol or isopropanol. The alcohol is then removed and the pectin is dried and standardized.
The type of pectin made is based on the processing conditions. A pectin is considered high-methoxyl (HM) when more than half of the carboxyl groups in the pectin are methyl esters. A low-methoxyl (LM) pectin is when less than half of the carboxyl groups are in the methyl ester form. A LM pectin can also be considered amidated if the pectin is treated with ammonia dissolved in methanol. This process converts 15-25% of the methyl ester groups into carboxamide groups.
How It Works
Gels are unique; they have the ability to hold water, sugar, etc. into a set shape using a three-dimensional network of polymers. The gel structure gives the product a different texture and mouthfeel when compared to other stabilizers such as corn starch. Pectin forms a crystalline-like network of junction zones when the carboxylate groups’ negative charges are removed. It can be done using acid, reducing molecule hydration using a co-solute, or adding divalent cations such as calcium. Junction zones are important because they trap the water while the pectin forms a network of cross-bridges. This leads us to the functional difference between HM and LM pectin.
HM pectin is more often used in traditional jams and jellies; it requires a certain amount of sugar and acid to properly gel. The pH needs to be lower, less than 3.5, to help neutralize and dehydrate the carboxylic acid groups. This allows the pectin to interact with each other and form junction zones. A high sugar content, 50-55+%, helps junction zone formation as well since the sugar competes for the available water. When the product is boiled, the sugar breaks down into glucose and fructose and binds with the water.
Conversely, LM pectin does not need sugar and acid to gel – it only needs to be in the presence of divalent cations such as calcium. This is useful when developing no/low sugar added jams and jellies. It can create a similar mouthfeel without the added sugar and calories. Since LM pectin has fewer methyl ester groups, the cations form ionic cross-bridges between the pectin strands. The amount of calcium is directly proportional to gel strength. It is important to balance the amount of pectin, acid, sugar, and calcium. If the gel is too strong, a process called syneresis occurs. Syneresis is when bonds reorganize causing water to leach out of the gel. If the gel is too weak, it would not be able to retain its shape which is important for some applications.
Nutrition/Health
From a medicinal standpoint, pectin can be taken as a supplement in the form of modified citrus pectin (MCP). It is modified to become digestible and has been a subject of a few clinical studies. It may lead to some health benefits such as lowering low-density lipoprotein cholesterol, controlling diarrhea, or treating heavy metal toxicity. Although these have not been proven, there have been no major risks for taking MCP by those who are not allergic to citrus fruits.
Apple pectin can be taken as a supplement as well. There have been claims that it may aid in gastrointestinal health, control blood sugar, slow down cancerous growth/progression, and enhance iron absorption. Overall, there have not been enough studies with the same outcome to make a definite decision. It does not seem like taking pectin will negatively affect your health but the benefits may not be that significant. The strongest claim supplemental pectin has is helping with diarrhea and constipation as it is a type fiber.
Final Thoughts
Humans have made jams and jellies for hundreds of years before they discovered how the fruit dictated the products’ set. Since then, we’ve used it in sauces, fiber supplements, and medicine. Pectin is a heteropolysaccharide that is able to form a gel network that traps water. It may be considered one of the least-processed stabilizers used in the food industry. Pectin can be regularly consumed without worry. There have been no major health concerns and may even be beneficial.
Resources
- https://www.chemistryworld.com/podcasts/pectin/3005903.article
- https://www.sciencedirect.com/topics/neuroscience/pectin
- https://books.google.com/books/about/Food_The_Chemistry_of_its_Components.html?id=-kO5CgAAQBAJ
- https://www.springer.com/gp/book/9781461425892
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3354751/
- https://www.webmd.com/vitamins-and-supplements/pectin-uses-and-risks#1
- https://www.healthline.com/nutrition/apple-pectin#6.-May-enhanceiron-absorption
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