Chemistry:Preservative
A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by undesirable chemical changes. In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails processes such as refrigeration or drying.[1] Preservative food additives reduce the risk of foodborne infections, decrease microbial spoilage, and preserve fresh attributes and nutritional quality. Some physical techniques for food preservation include dehydration, UV-C radiation, freeze-drying, and refrigeration. Chemical preservation and physical preservation techniques are sometimes combined.
Food preservation
Preservatives have been used since prehistoric times. Smoked meat for example has phenols and other chemicals that delay spoilage. The preservation of foods has evolved greatly over the centuries and has been instrumental in increasing food security. The use of preservatives other than traditional oils, salts, paints, [clarification needed] etc. in food began in the late 19th century, but was not widespread until the 20th century.[2]
The use of food preservatives varies greatly depending on the country. Many developing countries that do not have strong governments to regulate food additives face either harmful levels of preservatives in foods or a complete avoidance of foods that are considered unnatural or foreign. These countries have also proven useful in case studies surrounding chemical preservatives, as they have been only recently introduced.[3] In urban slums of highly populated countries, the knowledge about contents of food tends to be extremely low, despite consumption of these imported foods.[4]
Antimicrobial preservatives
Antimicrobial preservatives prevent degradation by bacteria. This method is the most traditional and ancient type of preserving—ancient methods such as pickling and adding honey prevent microorganism growth by modifying the pH level. The most commonly used antimicrobial preservative is lactic acid. Common antimicrobial preservatives are presented in the table.[5][6][7] Nitrates and nitrites are also antimicrobial.[8] The detailed mechanism of these chemical compounds range from inhibiting growth of the bacteria to the inhibition of specific enzymes.
| E number | chemical compound | comment |
|---|---|---|
| E200 – E203 | sorbic acid, sodium sorbate and sorbates | common for cheese, wine, baked goods, personal care products |
| E210 – E213 | benzoic acid and benzoates | used in acidic foods such as jams, salad dressing, juices, pickles, carbonated drinks, soy sauce |
| E214 – E219 | parabens | stable at a broad pH range |
| E220 – E228 | sulfur dioxide and sulfites | common for fruits, wine |
| E249 – E250 | nitrites | speed up the curing of meat and also impart an attractive colour, no effect on botulism bacteria[9][10] |
| E251 – E252 | nitrates | used in meats |
| E270 | lactic acid | - |
| E280 – E283 | propionic acid and propionates | baked goods |
| E338 | phosphoric acid | used in some jams, preserves and carbonated drinks; also used for acidification and for flavouring. |
Antioxidants
The oxidation process spoils most food, especially those with a high fat content. Fats quickly turn rancid when exposed to oxygen. Antioxidants prevent or inhibit the oxidation process. The most common antioxidant additives are ascorbic acid (vitamin C) and ascorbates.[11] Thus, antioxidants are commonly added to oils, cheese, and chips.[5] Other antioxidants include the phenol derivatives BHA, BHT, TBHQ and propyl gallate. These agents suppress the formation of hydroperoxides.[6]
| E number | chemical compound | comment |
|---|---|---|
| E300-304 | ascorbic acid, sodium ascorbate | cheese, chips |
| E321 | butylated hydroxytoluene, butylated hydroxyanisole | also used in food packaging |
| E310-312 | gallic acid and sodium gallate | oxygen scavenger |
| E220 – E227 | sulfur dioxide and sulfites | beverages, wine |
| E306 – E309 | tocopherols | vitamin E activity |
A variety of agents are added to sequester (deactivate) metal ions that otherwise catalyze the oxidation of fats. Common sequestering agents are disodium EDTA, citric acid (and citrates), tartaric acid, and lecithin.[1]
Nonsynthetic compounds for food preservation
Citric and ascorbic acids target enzymes that degrade fruits and vegetables, e.g., mono/polyphenol oxidase which turns surfaces of cut apples and potatoes brown. Ascorbic acid and tocopherol, which are vitamins, are common preservatives. Smoking entails exposing food to a variety of phenols, which are antioxidants. Natural preservatives include rosemary and oregano extract,[12] hops, salt, sugar, vinegar, alcohol, diatomaceous earth and castor oil.
Traditional preservatives, such as sodium benzoate have raised health concerns in the past. Benzoate was shown in a study to cause hypersensitivity in some asthma sufferers. This has caused reexamination of natural preservatives which occur in vegetables.[13]
Public awareness of food preservation
Public awareness of food preservatives is uneven.[14] Americans have a perception that food-borne illnesses happen more often in other countries. This may be true, but the occurrence of illnesses, hospitalizations, and deaths are still high. It is estimated by the Centers for Disease Control (CDC) that each year there are 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths linked to food-borne illness.[15]
Food suppliers are facing difficulties with regards to the safety and quality of their products as a result of the rising demand for ready-to-eat fresh food products. Artificial preservatives meet some of these challenges by preserving freshness for longer periods of time, but these preservatives can cause negative side-effects as well.
- Sodium nitrite is a preservative used in lunch meats, hams, sausages, hot dogs, and bacon to prevent botulism.[dubious ] It serves the important function of controlling the bacteria that cause botulism, but sodium nitrite can react with proteins, or during cooking at high heats, to form carcinogenic N-nitrosamines.[16][unreliable medical source?] It has also been linked to cancer in lab animals.[17]
- The commonly used sodium benzoate has been found to extend the shelf life of bottled tomato paste to 40 weeks without loss of quality.[11] However, it can form the carcinogen benzene when combined with vitamin C.[citation needed] Many food manufacturers have reformed their products to eliminate this combination, but a risk still exists.[17]
- Consumption of sodium benzoate may also cause hyperactivity in children, though the studies are inconclusive with a moderate effect size.[18]
Preservation of other products
Water-based home and personal care products use broad-spectrum preservatives, such as isothiazolinones and formaldehyde releasers, which may cause sensitization, leading to allergic skin.[19]
| Substance | Use |
|---|---|
| parabens | personal care products |
| isothiazolinones (MIT, CMIT, BIT) | not for food: home and personal care products, paints/coatings |
| formaldehyde releasers (DMDM hydantoin) | not for food: home and personal care products |
See also
References
- ↑ 1.0 1.1 Erich Lück and Gert-Wolfhard von Rymon Lipinski "Foods, 3. Food Additives" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi: 10.1002/14356007.a11_561
- ↑ Evans, G., de Challemaison, B., & Cox, D. N. (2010). "Consumers' ratings of the natural and unnatural qualities of foods". Appetite 54 (3): 557–563. doi:10.1016/j.appet.2010.02.014. PMID 20197074.
- ↑ Ashagrie, Z. Z., & Abate, D. D. (2012). IMPROVEMENT OF INJERA SHELF LIFE THROUGH THE USE OF CHEMICAL PRESERVATIVES. African Journal of Food, Agriculture, Nutrition & Development, 12(5), 6409-6423.
- ↑ Kumar, H., Jha, A., Taneja, K. K., Kabra, K., & Sadiq, H. M. (2013). A STUDY ON CONSUMER AWARENESS, SAFETY PERCEPTIONS & PRACTICES ABOUT FOOD PRESERVATIVES AND FLAVOURING AGENTS USED IN PACKED /CANNED FOODS FROM SOUTH INDIA. National Journal of Community Medicine, 4(3), 402-406.
- ↑ 5.0 5.1 Msagati, Titus A. M. (2012). The Chemistry of Food Additives and Preservatives. Retrieved from http://www.eblib.com
- ↑ 6.0 6.1 Dalton, Louisa (November 2002). "Food Preservatives". Chemical and Engineering News 80 (45): 40. doi:10.1021/cen-v080n045.p040. http://pubs.acs.org/cen/science/8045/8045sci2.html. Retrieved 9 February 2012.
- ↑ "Using Preservatives". http://www.understandingfoodadditives.org/pages/Ch2p5-3.htm.
- ↑ Shaw, Ian C. (2012). Food Safety : The Science of Keeping Food Safe. Retrieved from http://www.eblib.com (306- 334)
- ↑ Wilson, Bee (2018-03-01). "Yes, bacon really is killing us" (in en-GB). The Guardian (London). ISSN 0261-3077. Archived from the original on 2021-02-10. https://web.archive.org/web/20210210183650/https://www.theguardian.com/news/2018/mar/01/bacon-cancer-processed-meats-nitrates-nitrites-sausages. "In trade journals of the 1960s, the firms who sold nitrite powders to ham-makers spoke quite openly about how the main advantage was to increase profit margins by speeding up production."
- ↑ Doward, Jamie (2019-03-23). "Revealed: no need to add cancer-risk nitrites to ham". The Observer (London). Archived from the original on 2021-01-26. https://web.archive.org/web/20210126134441/https://www.theguardian.com/food/2019/mar/23/nitrites-ham-bacon-cancer-risk-additives-meat-industry-confidential--report. "The results show that there is no change in levels of inoculated C. botulinum over the curing process, which implies that the action of nitrite during curing is not toxic to C. botulinum spores at levels of 150ppm [parts per million] ingoing nitrite and below."
- ↑ 11.0 11.1 (Bhat, Rajeev; Alias, Abd Karim; Paliyath, Gopinadham (2011). Progress in Food Preservation. Retrieved from http://www.eblib.com
- ↑ Riva Pomerantz (Nov 15, 2017). "KOSHER IN THE LAB". Ami (342): 88.
- ↑ P'EREZ-D'IAZ, I.M; MCFEETERS, R.F (May 2010). "Preservation of Acidified Cucumbers with a Natural Preservative Combination of Fumaric Acid and Allyl Isothiocyanate that Target Lactic Acid Bacteria and Yeasts.". Journal of Food Science 75 (4): M204–M208. doi:10.1111/j.1750-3841.2010.01587.x. PMID 20546411. https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=43163&content=PDF.
- ↑ Kumar, H. N. Harsha; Jha, Anshu Kumar; Taneja, Khushboo K.; Kabra, Krishan; Sadiq, Hafeez M. (2013). A Study On Consumer Awareness, Safety Perceptions & Practices about Food Preservatives and Flavouring Agents used in Packed/Canned Foods from South India. National Journal of Community Medicine, 4(3), 402.
- ↑ Theron, M. M. & Lues, J. F. (2007). Organic acids and meat preservation: A review. Food Reviews International, 23, 141-158.
- ↑ Field, Simon Quellen (2008). Why There's Antifreeze in Your Toothpaste: The Chemistry of Household Ingredients. Chicago: Chicago Review Press.
- ↑ 17.0 17.1 Antinoro, L. (2008). EN Rates 12 Common Food Additives As Safe Or Sorry Ingredients. (Cover story). Environmental Nutrition, 31(5), 1-4.
- ↑ Barrett, J. R. (2007). "Hyperactive Ingredients?". Environmental Health Perspectives 115 (12): A578. doi:10.1289/ehp.115-a578. PMID 18087571.
- ↑ "The search is on for new cosmetic preservatives" (in en). https://cen.acs.org/business/consumer-products/search-new-cosmetic-preservatives/96/i39.
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