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A preservative is a naturally occurring or synthetically produced substance that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes. Preservatives can be divided into two types, depending on their origin. Class I preservatives refers to those preservatives which are naturally occurring, everyday substances. Examples include salt, honey and wood smoke.[1] Class II preservatives refer to preservatives which are synthetically manufactured.[1]

In wood[edit]

Preservatives may be added to wood to prevent the growth of fungi as well as to repel insects and termites. Typically arsenic, copper, chromium, borate, and petroleum based chemical compounds are used. For more information on wood preservatives, see timber treatment.

In food[edit]

Preservatives are often added to food to prevent their spoilage, or to retain their nutritional value and/or flavor for a longer period.

Health issues of Preservatives

Preservatives are a type of food additive that is used to extend and preserve their shelf life while keeping them from being destroyed and broken down by microorganisms such as bacteria, germs, or viruses. These microorganisms can cause food spoilage and decay.[2] Here are some of the health issues associated with specific types of food preservatives: .[3]Sulfites – is used for stopping browning and discoloration of food. The health issues related to the additive is that it links to asthma-related sensitivity and sometimes allergies. • Sodium Benzoate – can be found in sodas and various fruit juices. It helps to reduce the speed of fermentation and acidification of foods. As stated on Seattle Organic Restaurants webpage, researchers have found that when this type of preservative is mixed with vitamin c, it can create benzene (a known carcinogen-poison type chemical), which has harmful side effects, but only when a consumers consumes gallons of these benzene-filled beverages. • Sodium Nitrate and Nitrite – is a substance added to processed and canned foods and is often found in processed meat products such as bacon, ham, corn beef, sausage, as well hot dogs. As stated in the Micha research study, people should lessen the consumption of these processed meats to avoid nitrite’s intake, which have been link to various types of cancers.[4] • BHA/BHT – these substances help to preserve oils and fats in cosmetics and foods. According to the Seattle Organic Restaurant webpage, various research studies have indicated that these substances may be considered safe yet other researchers have found BHA to contain carcinogen. BHT has been associated with both increased and decreased risk of cancer, also affecting one’s sleep, increases appetite, causes liver and kidney damage, baldness, behavioral damage, and growth retardation.[5]MSG (Monosodium Glutamate) –used in flavoring food can be found in low fat milk, candy, chewing gum, fruit yogurts etc., and can cause headaches, nausea, weakness, burning sensation in back of neck or forearms, difficulty in breathing, change in pulse rate and heart rate etc.

In recent decades researcher Clarissa Adkins along with a multitude of others have conducted over 260 studies which have shown a link between pesticides and the fact that it is cancer causing. These cancers range from breast, prostate, brain, bone, thyroid, colon, liver, lung, and more. Pesticides have also been known to cause obesity, diabetes, high blood pressure, and Autism.[6] A Harvard study was conducted which linked pesticides in foods to Autism for mothers who were pregnant who consumed these products and for children in their first years of development who consumed these products.[7] Pesticides have also been shown to cause a rise in high blood pressure. This rise in high blood pressure was seen when individuals consumed processed meats over meats which were not processed and because of eating these meats which are processed these individuals are at a 30% higher risk of having cardiovascular diseases.[8]

Preservatives in food can be divided into two main categories:

Preservatives in Meat

The most common routes of preserving meats are through salts, sugars or a combination of chemical additives. These chemical additives include nitrates and nitrites, which are used to aid color stabilization and flavor development. These have been linked to the potential formation of nitrosamines, a compound that can be dangerous for human health and has carcinogenic effects at high levels. Sulfites are also common among internationally packaged foods. They are used in foods and beverages to prevent bacterial growth but are also known for giving a bright colored appearance to the substances that contain them. Due to high associations with allergic reactions, especially among children, sulfites are not allowed in American meat products. Other classes of preservatives are sorbates, benzoates and p-hydroxybenzoates.[14]

Preservatives are used in both processed meat from unprocessed meat, though there is a big difference between the two. The common non-processed meats are chicken, beef, lamb, pork, hamburger, and turkey. Processed meats can include bacon, hot dogs, sliced lunchmeat, as well as aged salamis and pepperoni.[15] Processed meats contain on average of 400% more sodium and 50% more nitrates.[16] There are several health effects that are a result of a diet that heavily consists of processed meats. For a long time, there was controversy over the health effects of red meat, but recently there has been evidence to show that it is not red meat but the processed meats that can cause heart disease or certain types of cancer.[17]

Recently, there has been a movement towards more natural preservatives. Organic acids have been introduced as preservatives in meat (Theron & Lues, 2007, p. 148). It is theorized that they could be an alternative to harsher preservatives that carry some of the health risks. Since they are new they have already ran into problems, such as resistant strains.[18] Food-based fermentae from Lactobacillus acidophilus has also recently been shown to extend the life of pork patties for up to three days.[19]

Public Awareness of Food Preservatives

Public awareness of food preservatives is not at par with other health issues. In a recent South Indian study, knowledge of preservatives was shown to be inadequate. Most interviewed were unaware of the potential health effects that food additives have been associated with, such as obesity, allergies, and asthma. As a result, only 17% of those interviewed were wary of buying products with food preservatives in them. 21% admitted to using food products with additives daily.[20] Americans have a perception that food-borne illnesses happen more often in other counties. This may be true, but the occurrence of illnesses, hospitalizations, and deaths are still high. It is estimated by the Center for Disease Control (CDC) that each year there are 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths linked to food-borne illness.[18]

FDA standards do not currently require fruit and vegetable product labels to reflect the type of chemical preservative(s) used on the produce.[citation needed]

Natural food preservation[edit]

Natural Preservatives are preservatives that come from natural sources. Natural preservatives are used for many different things such as food and cosmetics. They can be used as safer substitutes for artificial preservatives and a healthier alternative for humans.

Naturally occurring substances such as rosemary extract, hops, salt, sugar, vinegar, alcohol, diatomaceous earth and castor oil are also used as traditional preservatives. Certain processes such as freezing, pickling, smoking and salting can also be used to preserve food. Another group of preservatives targets enzymes in fruits and vegetables that start to metabolize after they are cut. For instance, the naturally occurring citric and ascorbic acids in lemon or other citrus juice can inhibit the action of the enzyme phenolase which turns surfaces of cut apples and potatoes brown if a small amount of the juice is applied to the freshly cut produce. Vitamin C and Vitamin E are also sometimes used as preservatives.

Research done by the Journal of Food Safety stated that using lemon extract as a natural preservative could prolong the shelf life of fresh fruit salad in supermarkets. This provides benefits to the industry by extending shelf life for buyers. It also proves that the use of natural ingredients to extend shelf life is a safer alternative for the environment and can replace the use of chemical preservatives.[21]

Another study done by the Journal of Applied Microbiology talks about the use of lavender, tea tree, and lemon as a natural preservative in oils of water body milks. The aim of this study was to develop a preservative system for cosmetics that would replace artificial preservatives with natural ingredients. The use of preservatives in cosmetics is to confirm that the products do not have imperfections or faults during production, packaging, and usage. These ingredients were tested as a substitute for artificial preservatives in cosmetics. In this experiment, it seems that these oils are not any better than using man made preservatives. However, a preservative system using both natural oils and artificial preservatives could be seen as a beneficial solution in this case.[22]

Traditional preservatives such as sodium benozoate have raised health concerns. Benzoate was shown in a study to cause hypersensitivity in some athsma sufferers. This has caused scientists to examine natural preservatives which occur in vegetables such as the cucumber for potential alternatives to traditional preservatives such as Benzoate.[23]

Health concerns[edit]

Some modern synthetic preservatives have been shown to cause respiratory or other health problems.[citation needed] For example sulfites are commonly used in wines and some dried fruits or vegetables and are known as possible irritants to people with asthma. In one study, 3-year-old and 8-9-year-old children exhibited increased hyperactivity after consuming drinks containing sodium benzoate or artificial food color.[24][misleading] Prior studies were however inconclusive.[citation needed] >


Natural Food Preservation[edit]

Food products begin to decompose immediately after they are harvested, so humans have had to compensate for this in order to preserve food for future use. The advent of chemical preservatives is relatively recent, so humans have found multiple processes that delay the decomposition.


Wood smoke has been traditionally used to preserve meat. "The smoke contains a number of antimicrobial compounds such as phenols, syringol, and guaiacol and their derivatives as well as carbonyls, catechol as well as naphthalene derivatives." [25] These compounds aid in the drying and preservation of meats and other foods.


Drying is one of the oldest techniques used to hamper the decomposition of food products. As early as 12,000 B.C. Middle Eastern and Oriental cultures were drying foods using the power of the sun. Vegetables and fruit are naturally dried by the sun and wind, but in the Middle Ages, "still houses" were built in areas that didn't have enough sunlight to dry things. A fire would be built inside the building to provide the heat to dry the various fruits, vegetables, and herbs.[26]


Any culture that has freezing temperatures for at least part of the year made use of them for food preservation. Less than freezing temperatures, like in caves, cellars, and cool streams, can prolong storage time as well.[26] "Freezing and chilling slows down both the metabolic and enzymatic activities for the microbes, thus discouraging their growth and multiplication. Chilling and freezing only slows down the growth; the processes do not kill the pathogens. This approach needs to be coupled with other preservative means to effectively preserve foodstuffs."[25]


Fermentation happens when microorganisms process the starch-derived sugars into alcohol. Not only can fermentation produce alcohol, but it can also be a valuable preservation technique. Fermentation can also make foods more nutritious and palatable. For example, drinking water in the Middle Ages was dangerous because it often contained pathogens that could spread disease. When the water is made into beer, it kills any bacteria in the water that could make you sick. Additionally, the water now has the nutrients from the barley and other ingredients, and the microorganisms can also produce vitamins as they ferment.[26]


Pickling is the process of preserving food in vinegar or other acid. "Lowering of the pH environment where food is kept may discourage the multiplication of microbial cells, since this also suppresses the metabolic and enzymatic activity of the microbial pathogens."[25] This process of preservation may have been discovered when food was placed in wine or beer, and it just happened to be preserved. This process had to be done in stoneware or glass, because the vinegar would dissolve the metal of the pots. In the sixteenth century, there was an increase in the use of food preservation when many new foods entered Europe. Ketchup originally began as an oriental fish brine that was brought to Europe by the spice routes, and eventually made it to America where sugar was added to the recipe. Soon it was discovered that spices could be added to these pickling sauces, and chutneys, relishes, mustards, and ketchups were commonplace. Worchester sauce, for example, was created accidentally when a barrel of special relish was forgotten and was allowed to age for many years in the basement of the Lea and Perrins Chemist shop.[26]


The earliest form of curing was actually dehydration, and many cultures used salt to help this process. In the culinary world it was common to choose raw salts from various sources (rock salt, sea salt, etc).[26] More modern "examples of salts that are used as preservatives include sodium chloride (NaCl), sodium nitrate NaNO3 and sodium nitrite (NaNO2). Even at mild concentrations (up to 2%) sodium chloride (which is present in many food products) is capable of neutralizing the antimicrobial character of natural compounds."[25]


The earliest cultures have used sugar as a preservative, and it was commonplace to store fruit in honey. Similar to pickled foods, sugar cane was brought to Europe through the trade routes. In northern climates without sufficient sun to dry foods, preserves are made by heating the fruit with sugar.[26] "Sugar tends to draw water from the microbes (plasmolysis). This process leaves the microbial cells dehydrated, thus killing them. In this way, the food will remain safe from microbial spoilage."[25]


Canning is a preservation process that involves jarring food, and then heating the jars until the microorganisms are destroyed and the enzymes are inactivated. This heating and cooling of the jar forms a vacuum seal, which prevents other microorganisms from contaminating the food. Canning is by far the newest form of food preservation, discovered[ by Nicolas Appert in the early 1790's. This French confectioner discovered that applying heat to sealed glass bottles preserved the food inside. By 1806, this process was used by the French Navy to preserve meat, fruit, vegetables, and even milk. Although Appert had discovered a new way of preservation, it wasn't understood until 1864 when Louis Pasteur found the relationship between microorganisms, food spoilage, and illness.[26]

Chemical Preservative Use[edit]

The preservation of foods has evolved greatly over the centuries, and has been instrumental in increasing food security. The use of chemical preservatives (other than traditional oils, salts, etc.) in food began in the late 19th century, but were not widespread until the 20th century as governments began regulating their use, and exploring their risks and benefits. As food additives for preservation came into widespread public consumption, certain factions of health advisers and concerned parents began to question the side effects of these chemicals. Consumers found that the additives were helpful and allowed for bulk buying and storage, while manufacturers enjoyed their profitability, as they could extend the shelf life of a product and therefore allow for much more long-distance shipping of foods. However, there is increasing debate in popular consumption of preservatives as there is increasing demand for products being natural rather than chemically preserved. Of course, the definition of 'natural' is much disputed.[27]

The major debate that goes on today about preservatives has to do with their effect on the health of consumers. Anti-preservative advocates argue that preservatives should be avoided in favor of more natural options, while those who support preservative use maintain that chemical preservatives have no negative effects on the consumer, and hold many benefits for increasing food supply.[28] The compendium of studies related to preservative effect on health have been largely inconclusive, as various studies have had conflicting findings, and many have had problems with keeping children's diets consistent or well-documented. One of the more prominent arguments against preservative usage asserts that preservative consumption can be linked to ADHD in children. Other claims include health risks that are closely related to sugar and fat intake - which makes their specific cause difficult to identify. In 1982 the American National Institutes of Health issued a statement saying that there is no scientific evidence to substantiate claims that chemical preservatives cause hyperactivity in children. They have since removed this statement, not connecting themselves to either side of the debate.[29]

The global use of food preservatives varies greatly depending on 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.[30] This issue of global circulation is also complicated by relationships between countries and importations from wealthy countries that negatively impact the profits of small farmers. In urban slums of highly populated countries the knowledge about contents of food tends to be extremely low, despite consumption of these imported foods.[31]


  1. ^ a b
  2. ^ (n.d) “ The Problem with Pesticides” (Accessed on May 9th 2014)
  3. ^ (n.d) “ Top 10 Toxic Foods, Preservatives, and Additives”
  4. ^ Micha, R., Michas, G., Lajous, M., & Mozaffarian, D. (2013). Processing of meats and cardiovascular risk: time to focus on preservatives. BMC Medicine, 11(1), 1-4. doi:10.1186/1741-7015-11-136. (Accessed on May 18th 2014).
  5. ^ Harrington, C. D. “Sodium Sulphite: A Dangerous Food-Preservative.” The Journal of Infectious Diseases, 1 (2), 335-337
  6. ^ Adkins, Clarissa. (August 16, 2013). What Are the Dangers of Food Preservatives? Livestrong Foundation, Retrieved from (Accessed on May 11, 2014)
  7. ^ Garber, L. (2012). “7 Nasty and Crazy Effects of Pesticides in Food, Exposure. exposure-1350220273. (Accessed on May 5th 2014)
  8. ^ Micha, R., Michas, G., Lajous, M., & Mozaffarian, D. (2013). Processing of meats and cardiovascular risk: time to focus on preservatives. BMC Medicine, 11(1), 1-4. doi:10.1186/1741-7015-11-136. (Accessed on May 18th 2014)
  9. ^ a b Dalton, Louisa (November 2002). "Food Preservatives". Chemical and Engineering News 80 (45): 40. doi:10.1021/cen-v080n045.p040. Retrieved 9 February 2012. 
  10. ^ "Using Preservatives". Retrieved 9 February 2012. 
  11. ^ Shaw, Ian C. (2012). Food Safety : The Science of Keeping Food Safe. Retrieved from (306- 334)
  12. ^ (Bhat, Rajeev; Alias, Abd Karim; Paliyath, Gopinadham (2011). Progress in Food Preservation. Retrieved from
  13. ^ Msagati, Titus A. M. (2012). The Chemistry of Food Additives and Preservatives. Retrieved from
  14. ^ Ruiz-Capillas, C. &Jimenez-Colmenero, F. (2008). Determination of preservatives in meat products by flow injection analysis (FIA). Food Additives and Contaminants, 25(10), 1167-1178.
  15. ^ Yoquinto, L. (2011, December 30). The Truth About Nitrite in Lunch Meat. Retrieved May 8, 2014, from
  16. ^ Micha, R. Michas, G. Lajous, M. & Mozaffarian, D. (2013). BMC Medicine, 11 (136), 1-4.
  17. ^ Harvard Heart Letter (2010). Read meat: Avoid the processes stuff
  18. ^ a b Theron, M. M. & Lues, J. F. (2007). Organic acids and meat preservation: A review. Food Reviews International, 23, 141-158.
  19. ^ Qianying, Z., Yingjian, L., Xiaoxi, L., Xiaomei, B., Fengxia, L., & Zhaoxin, L. (2014). Preservative Effect of Food-Based Fermentate from Lactobacillus acidophilus NX2-6 on Chilled Pork Patties. Journal Of Food Protection, 77(3), 459-465. doi:10.4315/0362-028X.JFP-13-359 (Accessed 5 May 2014
  20. ^ 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.
  22. ^ Kunicka-Styczynska, A. A.; Sikora, M. M., Kalemba, D. D. "Antimicrobial activity of lavender, tea tree and lemon oils in cosmetic preservative systems". Journal of Applied Microbiology: 1903–1911. 
  23. ^ 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. 
  24. ^ McCann, D.; Barrett, A.; Cooper, A.; Crumpler, D.; Dalen, L.; Grimshaw, K.; Kitchin, E.; Lok, K.; Porteous, L.; Prince, E.; Sonuga-Barke, E.; Warner, J. O.; Stevenson, J. (2007). "Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: A randomised, double-blinded, placebo-controlled trial". The Lancet 370 (9598): 1560–1567. doi:10.1016/S0140-6736(07)61306-3. PMID 17825405.  edit
  25. ^ a b c d e Msagati, T. (2012). “The Chemistry of Food Additives and Preservatives”
  26. ^ a b c d e f g Nummer, B. (2002). “Historical Origins of Food Preservation” (Accessed on May 5, 2014)
  27. ^ 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
  28. ^ Rhodes, M. E. (1979). The "Natural" Food Myth. Sciences, 19(5), 11.
  29. ^ Food additives and hyperactivity: Is There a Link?. (2004). Brown University Child & Adolescent Behavior Letter, 20(10), 1-4.
  30. ^ 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.