Emulsifiers for food use

Emulsifiers are additives that can be added to processed foods to improve their stability, consistency, or shelf life.[2][3][9]
From a chemical point of view, emulsifiers are surfactants, specifically amphipathic molecules, as they have both a hydrophilic and a hydrophobic region.[9]
There are over 60 different emulsifiers, and they are among the most commonly used additives in the food industry.[13]
Like other food additives, emulsifiers are identified by their name and/or a code number, known as the E numbering system, where “E” stands for Europe.[8][14]
The safety of food additives, and therefore of emulsifiers, is assessed by the competent authorities on the basis of the scientific literature available at the time of the assessment.[6] Recent researches have highlighted that further evaluations are desirable regarding the safety of long-term intake of some emulsifiers, as positive correlations have been observed between their intake and the risk of cardiovascular disease and inflammatory bowel disease.[1][14]

Contents

What are emulsifiers?

Emulsifiers are surfactants, that is, molecules that reduce the surface tension of a liquid, promoting miscibility between different liquids or the wettability of surfaces.
They are amphipathic molecules, also called amphiphilic molecules, that is, molecules that have a hydrophilic region, which are soluble in water and are characterized by the presence of polar groups, such as hydroxyl and carboxylic groups, and a lipophilic region, which is soluble in lipids and is characterized by the presence of non-polar groups, such as methyl groups, methylene bridges, or benzene rings.[2]
Other examples of amphipathic molecules are phospholipids, one of the main components of cell membranes, and bile salts, which are essential in the process of lipid digestion in the small intestine.[10]

What are they used for?

Emulsifiers perform multiple functions.
They assist the dispersion of mutually insoluble phases, that is, the aqueous and fatty phases, and allow the formation of stable mixtures, whether they are emulsions, foams, or colloids. Furthermore, by preventing the separation between the aqueous and fatty phases of the food, they extend shelf life and improve appearance and consistency.[1][13]
Emulsifiers, interacting with food components such as proteins, carbohydrates, ions, and water, also affect other properties of the processed food. In dairy processing, they can displace proteins at air/water and fat/water interfaces, modifying the properties and stability of the food.[9] In bread and other baked goods, emulsifiers help improve volume and crumb structure, and slow down starch retrogradation, that is, in the case of bread, they prevent staling.[2][9] In chocolate, they improve the rheological properties such as deformability and viscosity, and prevent fat blooming, which is the crystallization of triacylglycerols at the surface of chocolate.[2][15]
The most commonly used emulsifiers include:

  • lecithins, used to make many chocolate;
  • monoglycerides and diglycerides of fatty acids (E471), used, for example, in ice cream;
  • guar gum (E412), added to dairy products;
  • carrageenan (E407), added to ice cream and frozen desserts, flavoured milk, and iced coffee;
  • xanthan gum (E415), used to make, for example, mayonnaise;
  • different types of cellulose, from E460 to E469, found in food and vitamin supplements;
  • polysorbates, from E432 to E436, added to products such as icing, chocolate syrup, ice cream, cake mixes, and edible oils.[1][4][7][11]

Natural and artificial emulsifiers

Emulsifiers, like other food additives, can be of natural origin, either from plant or animal sources, or artificial. Among the emulsifiers of natural origin are lecithins (E322), agar-agar (E406), and guar gum (E412). Examples of synthetic emulsifiers are polysorbates, which are derived from polyethoxylated sorbitan conjugated with fatty acids, such as lauric acid, palmitic acid, oleic acid, or stearic acid.[9]
Skeletal formula of some emulsifiers: alginic acid (E400), carrageenan (E407), and polysorbate 80 (E433).Several emulsifiers are instead derived from chemical modifications of molecules of natural origin, modifications that alter the properties of the original molecule. Examples include sucrose esters (E473) and sucroglycerides (E474).[11]

Health effects

In vitro and mouse studies, as well as population studies, have shown that certain emulsifiers may have adverse effects on the gastrointestinal and cardiovascular systems.
The consumption of processed foods containing emulsifiers is among the factors that seem to favor the development of inflammatory bowel disease.[1] Among the proposed mechanisms are changes in the gut microbiota and/or intestinal barrier dysfunction that would allow the passage of bacteria and increase antigen exposure.[5][11][12]
A prospective cohort study pointed out a positive correlation between high intakes of cellulose, and monoglycerides and diglycerides of fatty acids, respectively, with the risk of coronary heart disease and cerebrovascular disease.[14]

References

  1. ^ a b c d Bancil A.S., Sandall A.M., Rossi M., Chassaing B., Lindsay J.O., Whelan K. Food additive emulsifiers and their impact on gut microbiome, permeability, and inflammation: mechanistic insights in inflammatory bowel disease. J Crohns Colitis 2021;15(6):1068-1079. doi:10.1093/ecco-jcc/jjaa254
  2. ^ a b c d Belitz H.-D., Grosch W., Schieberle P. Food Chemistry. 4th Edition. Springer, 2009.
  3. ^ Commission Regulation (EU) No 1129/2011 of 11 November 2011 amending Annex II to Regulation (EC) No 1333/2008 of the European Parliament and of the Council by establishing a Union list of food additives. https://eur-lex.europa.eu/eli/reg/2011/1129/2013-11-21
  4. ^ Cox S., Sandall A., Smith L., Rossi M., Whelan K. Food additive emulsifiers: a review of their role in foods, legislation and classifications, presence in food supply, dietary exposure, and safety assessment. Nutr Rev 2021;79(6):726-741. doi:10.1093/nutrit/nuaa038
  5. ^ Csáki K.F. Synthetic surfactant food additives can cause intestinal barrier dysfunction. Med Hypotheses 2011;76(5):676-81. doi:10.1016/j.mehy.2011.01.030
  6. ^ EFSA Food additives: EFSA’s new guidance for applicants. Published: 18 July 2012. https://www.efsa.europa.eu/en/press/news/120718a
  7. ^ EUFIC. What are emulsifiers and what are common examples used in food? Last Updated: 01 October 2022.
  8. ^ Food Standards Agency. Approved additives and E Numbers. Last updated: 23 January 2024.
  9. ^ a b c d e Hasenhuettl G.L. and Hartel R.W. (Eds.). (2008). Food emulsifiers and their applications. 3rd Edition New York: Springer, 2008.
  10. ^ Nelson D.L., Cox M.M. Lehninger. Principles of biochemistry. 6th Edition. W.H. Freeman and Company, 2012.
  11. ^ a b c Partridge D., Lloyd K.A., Rhodes J.M., Walker A.W., Johnstone A.M., Campbell BJ. Food additives: assessing the impact of exposure to permitted emulsifiers on bowel and metabolic health – introducing the FADiets study. Nutr Bull 2019;44(4):329-349. doi:10.1111/nbu12408
  12. ^ Roberts C.L., Keita A.V., Duncan S.H., O’Kennedy N., Söderholm J.D., Rhodes J.M., Campbell B.J. Translocation of Crohn’s disease Escherichia coli across M-cells: contrasting effects of soluble plant fibres and emulsifiers. Gut. 2010;59(10):1331-9. doi:10.1136/gut.2009.195370
  13. ^ a b Sandall A., Smith L., Svensen E., Whelan K. Emulsifiers in ultra-processed foods in the UK food supply. Public Health Nutr 2023;26(11):2256-2270. doi:10.1017/S1368980023002021
  14. ^ a b c Sellem L., Srour B., Javaux G., et al. Food additive emulsifiers and risk of cardiovascular disease in the NutriNet-Santé cohort: prospective cohort study. BMJ 2023;382:e076058. doi:10.1136/bmj-2023-076058
  15. ^ Trapp L., Karschin N., Godejohann M., Schacht H., Nirschl H., Guthausen G. Chemical composition of fat bloom on chocolate products determined by combining NMR and HPLC-MS. Molecules 2024;29(13):3024. doi:10.3390/molecules29133024

Biochemistry and metabolism