Preservatives are food additives added to foods that are at high risk of deterioration caused by microorganisms such as yeasts, bacteria and molds. Their action increases the shelf life of food products, ensures their safety, and avoids quality loss.[4][8]
There are different types of preservatives, each with specific modes of action.[11]
Like other food additives, preservatives are identified by their name and/or a code number, the E numbering system, where “E” stands for Europe, and are numbered from E200 to E299.[9]
Based on currently scientific evidence available, food additives are not harmful to human health. However, attention should be paid, among preservatives, to nitrates and nitrites. These molecules are not dangerous, but can become so following chemical modifications leading to the formation of N-nitrosamines, or simply, nitrosamines, compounds considered carcinogenic to humans.[14]
Contents
- How do preservatives work?
- What foods are they added to?
- Examples of preservatives
- Health effects of nitrates and nitrites
- References
How do preservatives work?
The modes of action of preservatives are multiple, but all aimed to inhibit the growth of pathogenic microorganisms.[16]
Among the modes of action of this class of food additives are the destruction of the cell membrane, enzymatic inhibition, inhibition of bacterial spore germination, and the formation of additive compounds.
Food spoilage can also be caused by non-microbial agents, such as chemical agents like oxidants, primarily oxygen, and physical agents, such as light and temperature.[7]
To prevent this type of spoilage, antioxidants are added to food, which, from this point of view, can also be considered preservatives. However, it should be noted that in this case, the function of the food additive is to prevent changes in the flavor and/or appearance, not to act as an antimicrobial, a role instead played by preservatives.[11]
On the other hand, certain preservatives, such as nitrates and sulphites, also act as antioxidants and, in some cases, as food colours.[11] For example, nitrates and nitrites help maintain the red color of meat and aid in developing the “seasoned” flavor.[10]
What foods are they added to?
The different types of preservatives are used preferentially in highly perishable foods, such as fishery products, therefore fish, molluscs and crustaceans, as well as in meat and dairy products.
Organic acids, such as propionic acid (E280), benzoic acid (E210), sorbic acid (E200), and their salts, are added to foods with a low pH. For example, sorbic acid and its potassium and calcium salts inhibit the growth of molds, yeasts and fungi in products such as wine, fruit juices, processed cheeses, and some baked goods like pastries. Note that the antimicrobial activity of sorbic acid increases as the pH of the medium decreases, as the fully protonated molecule is readily taken up by microorganisms.[18]
Nitrates and nitrites, specifically their sodium and potassium salts (E249-E252), are added to processed meats, such as sausages, sliced meats, canned meats, and certain cheeses. They are particularly effective at inhibiting the germination of Clostridium botulinum spores, the bacterium that causes botulism.[10]
Sulfur dioxide and sulphites (E220-E228) are added to foods such as wines, dried fruits, and fruit juices.[16]
Nisin (E234), a polycyclic polypeptide produced by the bacterium Lactococcus lactis and consisting of 34 amino acids, is a broad-spectrum bacteriocin effective against many Gram-positive bacteria and spores.[2] It is added to foods such as beverages, processed cheeses, and processed meats.
Natamycin, also known as NATA (E235), is a preservative that acts on molds and yeasts. It is used, for example, for the surface treatment of dairy products and processed meats, such as sausages. It is produced by certain bacterial species belonging to the genus Streptomyces.[3][6][15]
Examples of preservatives
Below is a brief overview of some preservatives included in the list of food additives approved by the European Community, according to Regulation 1129/2011 of the European Commission, published on November 11, 2011. This list is an amendment of Annex II to Regulation (EC) No. 1333/2008 of the European Parliament, and it was further amended in 2013.[4]
| E-number | Additive and derivatives | |
| Sorbic acid and its salts | ||
| E200 | Sorbic acid | |
| E202 | Potassium sorbate | |
| E203 | Calcium sorbate | |
| Benzoic acid and its salts | ||
| E210 | Benzoic acid | |
| E211 | Sodium benzoate | |
| E212 | Potassium benzoate | |
| E213 | Calcium benzoate | |
| E214 | Ethyl p-hydroxyhenzoate | |
| E215 | Sodium ethyl p-hydroxybenzoate | |
| E218 | Methyl p-hydroxybenzoate | |
| E219 | Sodium methyl p-hydroxybenzoate | |
| Sulphur dioxide and its salts | ||
| E220 | Sulphur dioxide | |
| E221 | Sodium sulphite | |
| E222 | Sodium hydrogen sulphite | |
| E223 | Sodium metabisulphite | |
| E224 | Potassium metabisulphite | |
| E226 | Calcium sulphite | |
| E227 | Calcium hydrogen sulphite | |
| E228 | Potassium hydrogen sulphite | |
| Other preservatives | ||
| E234 | Nisin | |
| E235 | Natamycin | |
| E239 | Hexamethylene tetramine or hexamine | |
| E242 | Dimethyl dicarbonate | |
| Nitrates and nitrites | ||
| E249 | Potassium nitrite | |
| E250 | Sodium nitrite | |
| E251 | Sodium nitrate | |
| E252 | Potassium nitrate or saltpetre | |
| Acids and their salts | ||
| E280 | Propionic acid | |
| E281 | Sodium propionate | |
| E282 | Calcium propionate | |
| E283 | Potassium propionate | |
| E284 | Boric acid | |
| E285 | Sodium tetraborate or borax | |
Health effects of nitrates and nitrites
In humans, the main sources of nitrates, which are harmless in themselves, are water and some vegetables, such as chard, arugula, lettuce, turnips, cabbage, celery, radishes, and spinach, while the main source of exogenous nitrites is processed meats.[13]
Nitrates and nitrites are rapidly absorbed in the intestine and mostly excreted as nitrites. However, approximately 25 percent of absorbed nitrates enter the salivary glands, and 5 percent is then released into the oral cavity, where bacterial reductases oxidize it to nitrites.[5]
Once in the stomach, due to the acidic environment, nitrites can be converted into nitrous acid, that readily reacts with amines, molecules present in foods high in proteins, such as meat and derivatives and cheese, to form nitrosamines, carcinogenic compounds. For these reasons, the International Agency for Research on Cancer has classified nitrates and nitrites as probably carcinogenic to humans (Group 2A).[12]
Therefore, excessive and prolonged consumption of processed foods containing nitrates and nitrites should be avoided, or at least severely limited, as it has also been associated with an increased risk of esophageal and stomach cancer. However, the use of nitrates and nitrites is justified by the fact that the benefits arising from their use, in the small, regulates amounts in foods susceptible to contamination by Clostridium botulinum outweigh the potential cancer risk.[1]
It is important to know that the intake of antioxidants, such as vitamin C (E300) and its sodium and potassium salts (E301 and E302), inhibits the formation of N-nitrosamines from nitrates and nitrites.[17]
References
- ^ AIRC. Gli additivi e i conservanti alimentari aumentano il rischio di tumori? Ultimo aggiornamento: 22 marzo 2023. https://www.airc.it/cancro/informazioni-tumori/corretta-informazione/additivi-conservanti-alimentari
- ^ And H.C., Hoover D.G. Bacteriocins and their food applications. Compr Rev Food Sci Food Saf 2003;2(3):82-100. doi:10.1111/j.1541-4337.2003.tb00016.x
- ^ Branen A.L., Davidson P.M., Salminen S., Thorngate J. Food Additives. 2nd Edition. CRC Press. 2001.
- ^ a b 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
- ^ EFSA. Panel on Food Additives and Nutrient Sources added to Food (ANS). Re-evaluation of sodium nitrate (E251) and potassium nitrate (E252) as food additives. EFSA J 2017;15(6):e04787. doi:10.2903/j.efsa.2017.4787
- ^ EFSA. Panel on Food Additives and Nutrient Sources added to Food (ANS). Scientific opinion on the use of natamycin (E235) as a food additive. EFSA Journal 2009;7(12):1412. doi:10.2903/j.efsa.2009.1412
- ^ EUFIC. What are preservatives and what are common examples used in food? Last Updated: 01 October 2022.
- ^ European Commission. Food safety. Additives. https://food.ec.europa.eu/food-safety/food-improvement-agents/additives_en
- ^ Food Standards Agency. Approved additives and E Numbers. Last updated: 23 January 2024.
- ^ a b Food Standards Agency. Food additives. Last updated: 26 January 2024. https://www.food.gov.uk/safety-hygiene/food-additives
- ^ a b c García-García R., Searle S.S. Preservatives: food use. Encyclopedia of Food and Health. 2016:505-509. doi:10.1016/B978-0-12-384947-2.00568-7
- ^ Grosse Y., Baan R., Straif K., Secretan B., El Ghissassi F., Cogliano V.; WHO International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of nitrate, nitrite, and cyanobacterial peptide toxins. Lancet Oncol 2006;7(8):628-9. doi:10.1016/s1470-2045(06)70789-6
- ^ Hord N.G., Tang Y., Bryan N.S. Food sources of nitrates and nitrites: the physiologic context for potential health benefits. Am J Clin Nutr 2009;90(1):1-10. doi:10.3945/ajcn.2008.27131
- ^ Jakszyn P., Gonzalez C.A. Nitrosamine and related food intake and gastric and oesophageal cancer risk: a systematic review of the epidemiological evidence. World J Gastroenterol 2006;12(27):4296-303. doi:10.3748/wjg.v12.i27.4296
- ^ Meena M., Prajapati P., Ravichandran C., Sehrawat R. Natamycin: a natural preservative for food applications-a review. Food Sci Biotechnol 2021;30(12):1481-1496. doi:10.1007/s10068-021-00981-1
- ^ a b Singh R.P., Davidson P.M. Food additive. Encyclopedia Britannica, 26 Sep. 2024. https://www.britannica.com/topic/food-additive. Accessed 28 October 2024.
- ^ Tannenbaum S.R., Wishnok J.S., Leaf C.D. Inhibition of nitrosamine formation by ascorbic acid. Am J Clin Nutr 1991;53(1 Suppl):247S-250S. doi:10.1093/ajcn/53.1.247S
- ^ Zeece M. Chapter Seven. Food additives. Introduction to the chemistry of food. Academic Press. 2020:251-311. doi:10.1016/B978-0-12-809434-1.00007-4