The use of Polyethylene Glycol 400 in the food industry

By Jillian Jastrzembski

Polyethylene Glycol 400

 

Overview of Polyethylene Glycol

Polyethylene glycol, or PEG, is a conveniently customizable molecule that can lend itself to many different applications, including many within the food industry. This polymer consists of a chain of repeating ethylene glycol units. The chain can be almost any length, resulting in multiple possible molecular weights.

The nomenclature of PEG molecules includes either the number of repeating units, or the molecular weight of the polymer, in the name of the compound. The properties of this polymer can change according to the length of the chain, making it extremely customizable. The polymer can also be derivatized with new functional groups to further increase its versatility.

The molecular weight of PEG is carefully selected based upon the desired application. For example, in the molecular weight range of 200 to 9500, PEG can be used as a food additive. The reasons for this are related not only to the functional properties, but also to the toxicology properties.

In this article, we’re focusing on the use of PEG 400 in the food industry. What is PEG 400, what are its properties, and how is it used?

What is PEG 400?

According to the standard nomenclature of PEG compounds, PEG 400 represents a chain of repeating ethylene glycol units, [-(CH2CH2O)n]. This chain amounts to a total average molecular weight of 400 g/mol. This falls within the range of PEG molecules that are typically used as food additives.

PEG 400 is a syrupy, viscous liquid at room temperature. In fact, this is true for all PEG chains between 100 until about 600 or 700 g/mol. As the molecular weight continues to increase, PEG becomes a soft solid. If it gets as heavy as 2000 g/mol, it develops a hard, crystalline structure.

Special properties of PEG 400

PEG has plenty of properties that lend itself to usefulness in the food and pharmaceutical industries. An obvious prerequisite for food and pharmaceutical use is that it is (mostly) nontoxic. Generally speaking, PEG is biologically inert. It does set off alarms in the body, or trigger a reaction from the immune system. It also does not adsorb to proteins, or infiltrate cells. It is an approved food additive in most countries, including the US.

Although PEG itself has only two functional groups, it can be further diversified by converting the terminal hydroxyl groups into more reactive functional groups. In this way, PEG 400 can be adapted to interact with a wider range of proteins and polysaccharides, making it even more useful in food industry applications. PEG can be modified to incorporate amino groups, carboxyl groups, aldehydes, and even inorganic materials or ionic bonds.

Use of PEG 400 in the food industry

PEG is an excellent solubilizing agent, because it straddles the gap between hydrophilic and hydrophobic molecules. This gives an emulsifying property, which is useful in food formulations that have immiscible ingredients. It is simultaneously a useful carrier for flavors and other additives. PEG is also known to form hydrogels, thanks to its water-holding capacity.

PEG is particularly promising in combination with polysaccharides. Polysaccharides offer the advantages of being naturally derived, accessible, renewable, and health-promoting. Yet, in terms of their physical properties, polysaccharides have shortcomings such as being brittle and inflexible. As a plasticizer, PEG can be incorporated into biopolymers in order to create a more flexible film for food packaging.

In combination with polysaccharides, PEG may also possess antimicrobial activity by influencing bacterial cell growth. There may additionally be some antioxidant activity, thanks to the presence of ether linkages, which may facilitate free radical scavenging. The implication is that PEG can help preserve bioactive compounds. Therefore, PEG is a useful ingredient for food delivery systems.

PEG is also said to have a “self-healing” property, meaning it repairs itself. This is thanks to the long, flexible chains and repeating hydrogen bonding sites on the PEG backbone. This presents repeated opportunities for cross-linking with polysaccharides.

Applications of PEG 400 and its derivatives

In summary, here is a list of some ways PEG 400 and its derivatives are used in the food industry:

  • Food packaging
  • Carrier for additives
  • Delivery systems
  • Coatings
  • Emulsifier

Useful Properties of PEG 400 and its derivatives

In summary, some of the special properties of PEG 400 and its derivatives include:

  • Antimicrobial
  • Antioxidant
  • Plasticizing
  • Self-healing

Conclusion

Polyethylene glycol 400, or PEG 400, is a chain of repeating ethylene glycol units, amounting to an average molecular weight of 400 g/mol. In the range of 200 to 9500 g/mol, PEG often finds use in the food industry thanks to its many useful properties. PEG is mostly non-toxic, biologically inert, and does not induce an immune response. It inherently possesses emulsifying and plasticizing properties, and can interact with biopolymers to create antimicrobial, antioxidant, and self-healing materials. PEG may be used within the food system as a carrier, emulsifier, as well as for food packaging, delivery systems, and food coatings.

References

Anisha A. D’souza & Ranjita Shegokar (2016) Polyethylene glycol (PEG): a versatile polymer for pharmaceutical applications, Expert Opinion on Drug Delivery, 13:9, 1257-1275, DOI: 10.1080/17425247.2016.1182485

H.W. Leung, Polyethylene Glycol, Editor(s): Philip Wexler, Encyclopedia of Toxicology (Third Edition), Academic Press, 2014, Pages 1043-1044, ISBN 9780123864550, https://doi.org/10.1016/B978-0-12-386454-3.00050-6.

Gong, Linshan, et al. “Effect of polyethylene glycol on polysaccharides: From molecular modification, composite matrixes, synergetic properties to embeddable application in food fields.” Carbohydrate Polymers (2023): 121647.

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