Is humectant 422 vegetarian?

In this brief guide, we will answer the query, “Is humectant 422 vegetarian?” and will discuss the production and application of humectant 422.

Is humectant 422 vegetarian?

Maybe, humectant 422 is vegetarian. Humectant 422 is also known as glycerol. Triglycerides, which are glycerol esters with long-chain carboxylic acids, are the most common forms of glycerol in plants and animals. Glycerol is formed when these triglycerides are hydrolyzed, saponified, or transesterified. It can be produced as  a by-product from saponification and hydrolysis reactions in oleochemical plants as well as transesterification reaction biodiesel plants (1). Palm oil and soybeans are two common plant sources. Another option is tallow obtained from animals. 

The so-called second generation glycerol developed the production of biodiesel from animal fat via transesterification process. Fats including beef fat and chicken fat (1).

What is glycerol?

Glycerol is a polyol chemical that is quite simple. Non-toxic, sweet-tasting, colorless, and viscous, it has no odor and is non-toxic. Glycerides are lipids that contain the glycerol backbone. It is commonly utilized in FDA-approved wound and burns therapies because of its antibacterial and antiviral characteristics. As a bacterial culture medium, it may also be utilized in the laboratory.

Glycerol is an alcohol that consists of a three-carbon chain with a hydroxyl group attached to each carbon. It is derived from natural or petrochemical feedstocks. Physically, glycerol is a clear, colorless, odorless, hygroscopic, vicious and sweet taste liquid. The boiling point and melting point and flash point of glycerol is 290°C and 18°C respectively. Under normal atmospheric pressure, glycerol has a molecular weight of 92.09 g/mol, a density of 1.261 g/cm3, and a viscosity of 1.5 Pa.s. The extensive intermolecular hydrogen bonding is responsible for high viscosity and boiling point of glycerol. Glycerol is able to attract and hold the moisture from the air and it is not altered when contact with the air (1).

 It is a useful biomarker for assessing the severity of liver disease. It is also frequently utilized in the food and pharmaceutical industries as a sweetener and humectant. Glycerol is water-miscible and hygroscopic due to the presence of three hydroxyl groups.

Glycerol Production

Triglycerides, which are glycerol esters with long-chain carboxylic acids, are the most common forms of glycerol in plants and animals. Glycerol is formed when these triglycerides are hydrolyzed, saponified, or transesterified.

Transesterification is a chemical reaction whereby fats and oils (triglycerides) react with alcohols such as methanol in the presence of a catalyst to produce fatty acid methyl esters with glycerol byproduct. As the transesterification reaction progresses, the reaction stream is separated in two phases, which are biodiesel-rich phase (toplayer) and glycerol-rich phase (bottom layer), due to differences in their densities and their polarities. The production of 100 kg of biodiesel yields approximately 10 kg of impure glycerol, with purity of 50–55% (1).

Palm oil and soybeans are two common plant sources. Another source is tallow obtained from animals. In the United States and Europe, around 950,000 tons of glycerol are produced annually; 350,000 tons of glycerol were produced per year in the United States alone from 2000 to 2004. Biofuels were mandated by EU regulation 2003/30/EC to replace 5.75 percent of petroleum fuels in all member states by 2010. In 2006, it was predicted that global glycerol output will be six times more than demand by 2020, resulting in a glut.

Triglycerides are used to make a significant amount of glycerol, however, the crude product is of inconsistent quality, and the selling price per kilogram in 2011 was as low as 2-5 cents in the United States. It is possible to purify it, but the procedure is costly. However, the heat value is minimal for glycerol that is burnt.

The quality of existing hydrolysed and biodiesel-derived glycerol is poor and unsuitable to be used as the feedstocks for further application as well as caused problems of disposal in biodiesel plant.Thus,purification is required to convert crude glycerol to ausable state,which has met the purity requirements for existing uses (1).

Different methods have been used to purify crude glycerol, such as distillation, filtration, chemical treatment, adsorption (using activated carbon), ion-exchange (using resin), extraction, decantation and crystallization whereby each of the purification techniques uses different properties of crude glycerol (1). 

Treatment with activated charcoal to remove organic impurities, alkali to remove unreacted glycerol esters, and ion exchange to remove salts may all be used to purify crude glycerol obtained from the hydrolysis of triglycerides. A vacuum chamber is required because of the high boiling point of glycerol (290 °C) to get high purity glycerol (>99.5%).


The food industry

Glycerol is a humectant, solvent, and sweetener in food and drinks, and it may help preserve goods. It is also used as a thickening ingredient in liqueurs and as a filler in professionally made low-fat meals (e.g., cookies). Glycerol and water are used to preserve the leaves of some plants. It is normally ingested in manufacturing extracts of tea, coffee, ginger and other vegetable substances. It is also used as a softening agent in bread, cakes, meats, cheese and candy. Glycerol can be used to preserve the freshness of tobacco (1).

 At 27 kilocalories per teaspoon, it is around 60 percent sweeter than sucrose, making it an excellent sugar alternative. As a result, it does not encourage the growth of germs that cause cavities in the mouth. Glycerol has the E number E422 as a food additive. For the icing (frosting), this is used to keep it from becoming too hard.

The American Academy of Nutrition and Dietetics classifies glycerol as a carbohydrate when it is utilized in food. All caloric macronutrients, except protein and fat, are included in the FDA’s carbohydrate categorization. There are some dietary advocates who accept glycerol as a sweetener suitable with low-carbohydrate diets because of its caloric density and lower glycemic index.

When using polyol sweeteners like erythritol and xylitol, which have a cooling impact owing to their heating effect in the mouth, it is also advised as an addition if the cooling effect is not desired because of its heating effect.

Applications in the fields of medicine, pharmaceuticals, and personal care

Using glycerin as a topical wound therapy is allowed by the FDA since it has some antibacterial and antiviral properties. A glycerin 85 percent solution has been shown by the Red Cross to be effective against bacteria and viruses, as well as reducing inflammation in wounds treated with glycerin after around two hours. Because of this, glycerin-based hydrogel sheets for burns and other wound care are commonly utilized. Skin grafts may be packaged using this product, which is allowed for wound treatment except for third-degree burns. Glycerin is not the only topical medication that cannot be used to treat third-degree burns.

Glycerol is often used in medical, pharmaceutical, and personal care products as a lubricant, a humectant, and to enhance the smoothness of the product. Topical glycerin has been shown to treat ichthyosis and xerosis. Its pharmaceutical uses include applications in some over-the-counter drugs, such as ophthalmic and dermal products, and external analgesic (3).

In allergy immunotherapy, cough syrup, elixirs and expectorants, toothpaste, mouthwashes, and skincare products as well as soaps and water-based personal lubricants. Glycerol is utilized as a tablet-holding agent in solid dosage forms like tablets. The U.S. Food and Drug Administration (FDA) classifies glycerol as a caloric macronutrient for human ingestion. The preservation of red blood cells before freezing is another application of glycerol in the blood banking industry.

Glycerin soap has glycerol as an ingredient. Fragrant essential oils are included in the recipe. Because of its hydrating characteristics, this soap is preferred by those with delicate, easily irritated skin. Moisture is drained from the lower layers of the skin and evaporation is slowed or prevented. citations required

Anal mucosa irritation and hyperosmotic effect drive water into the colon to stimulate peristalsis, which results in evacuation. Glycerol may be taken orally as a laxative. A suppository or a small-volume (2–10 ml) enema may be used to deliver it undiluted. As a large volume enema, it may be delivered at dilutions of up to 5%.

Eye pressure may be reduced rapidly and temporarily by taking glycerin orally (typically blended with fruit juice to diminish its sweetness). In the event of a significant rise in ocular pressure, this may be used as an early therapy.

In addition,glycerol is considered a renewable feedstock for the production of various chemicals, and a series of glycerol-derived liquids, such as 1,3-dialkoxy-2-propanols and 1,2,3-trialkoxy-propanes, have been tested as green solvents that could replace some petroleum-based ones. The use of glycerol and glycerol-derived solvents as alternative media for organic reactions has emerged as a promising new field of research, opening new ways to revalorize glycerol for applications in synthetic organic chemistry, catalysis and biocatalysis (3).

When Lactobacillus reuteri, a probiotic, was supplemented with glycerol to study the effects on Clostridium difficile cultivated in a lab, researchers discovered that the chemical reuterin, an antibiotic with a wide range of activity, was produced. C. difficile growth was inhibited by the reuterin as effectively as vancomycin. The researchers observed that glycerol or L. reuteri alone were not effective against C. difficile and that the reuterin did not affect the beneficial bacteria in the complex gut ecology. It was demonstrated that the ability for L. reuteri to inhibit C. difficile growth relies on reuterin production through glycerol fermentation (2).


In this brief guide, we answered the query, “Is humectant 422 vegetarian?” and discussed the production and application of humectant 422.


  1. Tan, H. W., AR Abdul Aziz, and M. K. Aroua. Glycerol production and its applications as a raw material: A review. Renew sustain en rev, 2013, 27, 118-127.
  2. Engevik, Melinda A., et al. Reuterin disrupts Clostridioides difficile metabolism and pathogenicity through reactive oxygen species generation. Gut Microb, 2020, 12, 1795388.
  3. Makris, Dimitris P., and Stavros Lalas. Glycerol and glycerol-based deep eutectic mixtures as emerging green solvents for polyphenol extraction: The evidence so far. Molecules, 2020, 25, 5842.

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