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Contaminants Produced During Processing. Acrylamide What is Acrylamide ? Acrylamide is a synthetic vinyl compound produced by the chemical industry mainly as a building block for various polymers, particularly polyacrylamide .

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  • What is Acrylamide?
  • Acrylamide is a synthetic vinyl compound produced by the chemical industry mainly as a building block for various polymers, particularly polyacrylamide.
  • Polyacrylamide is widely used in various applications, such as:
  • in the treatment of wastewater
  • in paper processing
  • in mining and mineral production.
  • Acrylamide is also present in cigarette smoke.
  • The wide use of polyacrylamide in industry means that human exposure to acrylamide is probable.

Occurrence in Foods

  • The possibility of acrylamide contamination of foods did not become widely known until 2002, when a report from the Swedish National Food Administration was published.
  • This report revealed that acrylamide could be produced in significant concentrations in certain carbohydrate-rich foods processed at relatively high temperatures, such as:
  • fried potato (chips)
  • fried foods
  • Chocolate
  • Coffee
  • baked cereal products such as:
  • Biscuits
  • Bread
  • toasted breakfast cereals

Acrylamideis not confined to commercially processed foods.

  • It can also be found in home-baked food.

Effects on Health

  • Acrylamide is a neurotoxin at high levels of exposure and may cause a range of symptoms such as numbness in the hands and feet.
  • It has also been shown to be genotoxic in animal studies.
  • Of more concern to the food industry is the finding that acrylamide is also carcinogenic in animal studies.
  • The International Agency on Research on Cancer (IARC) classifies it as ‘‘probably carcinogenic to humans (IARC Group 2A).’’


  • The original Swedish report into acrylamide in food in 2002 indicated that the contaminant is produced as a result of heating certain foods, especially those containing high levels of carbohydrate, at temperatures above 120 0C.
  • It is therefore a contaminant generated during processing.
  • The major mechanism for the formation of acrylamide during cooking is now acknowledged to be:
  • the reaction of the free amino acid asparagine with reducing sugars, such as glucose or fructose, during the Maillard browning reactions that occur during cooking at high temperatures.

***Asparagine is a non-essential amino acid.


The key factors that affect the quantity of acrylamideproduced appear to be;

  • amount of free asparaginepresent in the food
  • amount of sugars present in the food
  • cooking time
  • cooking temperature.

Stability in Foods

  • The large amount of data collected from food surveys suggests that acrylamide is relatively stable in food, but this has not been widely studied to date.
  • Nevertheless, acrylamide levels have been found:
  • not to decreasesignificantly in crisps or baked cereal products during shelf life
  • decreasesignificantlyin roast and ground coffee

Control Options

  • 1-Product Formulation
  • One obvious strategy for the control of acrylamide formation is to minimize the amount of free asparagine and reducing sugars in food prior to cooking.
  • The development of low-asparagine varieties of potato is one approach that is receiving attention.
  • The modification of product recipes also shows some promise. For example, replacing ammonium bicarbonate with other raising agents in baked products can reduce acrylamide formation significantly, as can a reduction in pH.


  • The main factors that can be modified to minimizeacrylamide formation are cooking time and temperature.
  • The ‘‘thermal input’’ to a cooking process has been shown to be directly linked to the amount of acrylamide produced.
  • As a general rule, higher thermal input results in higher levels, with the exception of coffee production, where acrylamide levels decrease with longer roasting times and ‘‘darker’’ roasts.

Reducing acrylamide by changing processing times and temperatures results in a compromise between product quality and safety.

  • Also, frying at lower temperatures may allow foods to take up higher levels of fat, which may be undesirable from a nutritional point of view.
  • While this may be successful, it must be recognized that the browning of baked and fried foods is an essential component in their sensory acceptability.


  • Acrylamideis not yet covered specifically by legislation in Europe or North America and no permitted limits have been set.


  • What is Benzene?
  • Benzene is an aromatic hydrocarbon compound used extensively in the chemical industry as an intermediate in the manufacture of polymers and other products.
  • It is also a common atmospheric contaminant and is present in motor vehicle exhaust emissions and cigarette smoke.
  • In 1990, it was discovered by the US soft drinks industry that benzene could be produced at low levels in certain soft drinks containing a benzoate preservative and ascorbic acid.
  • Since benzene is a known human carcinogen, its presence in food and beverages is clearly undesirable.

Occurrence in Foods

  • Detectable levels of benzene have been found in:
  • soft drinks that contain either a sodium or potassium benzoate preservative and ascorbic acid
  • ‘‘diet’’-type products containingno added sugar

Effects on Health

  • Although benzene can cause acute toxicity, especially when inhaled at high levels, it is its carcinogenicity that is of concern in foods and beverages.
  • Benzene is a proven carcinogen and has been shown to cause cancers in industrial workers exposed to high airborne levels.
  • Much less is known about its effects when ingested at low levels over long periods, but current risk assessments suggest that the contribution of soft drinks to benzene exposure levels is negligible, as is any additional risk to human health.


  • It has been established that the source of benzene in soft drinks is the decarboxylation of benzoic acid with presence of ascorbic acid and trace amounts of a suitable metal catalyst (copper or iron).
  • Elevated temperature and light are both reported to stimulate this reaction, whereas it is inhibited by sugars and by salts of EDTA.
  • This may be whybenzene is most likely to be found in diet drinks containing low sugar levels.

Stability in Foods

  • There is little information available on the stability of benzene in soft drinks during storage.

Control Options

  • The preferred approach for controlling the production of benzene in soft drinks is to reformulate the product.
  • Once a specific soft-drink formulation has been shown to be capable of generating benzene during storage, alternatives to benzoate preservatives, such as potassium sorbate, should be evaluated.
  • Benzene generation may be effectively prevented by the removal of benzoates from the product.
  • However, it should be noted that the majority of soft drinks containing benzoates and ascorbic acid have not been shown to produce benzene and may not need to be reformulated in this way.


  • Current US and European legislation does not set maximum limits for benzene in soft drinks.
  • However, the FDA has adopted the Environmental Protection Agency (EPA) maximum contaminant level (MCL) for drinking water of 5 parts per billion (ppb) as a quality standard for bottled water.
  • This MCL has been used to evaluate the significance of benzene contamination in the soft drinks tested in recent surveys.
  • The UK Food Standards Agency has used the World Health Organization (WHO) guideline level for benzene in water of 10 ppb as a point of reference for its own survey results.


  • What are Chloropropanols?
  • The chloropropanols are a group of related chemical contaminants that may be produced in certain foods during processing.
  • They first became a concern to the food industry in the late 1970s when small concentrations were found to be generated during the manufacture of acid-hydrolysed vegetable protein (acid-HVP) used as a savoury ingredient in:
  • Soups
  • Sauces
  • Chloropropanols are potentially carcinogenic and their presence in food, even at low levels is therefore undesirable.

Occurrence in Foods

  • The highest levels of chloropropanolshave been found in acid-HVP and in soy sauce and related products.
  • It is thought that the contaminant is usually produced during the manufacturing process, especially at high temperatures, but the mechanism is not known in all cases.

Effects on Health

  • Although chloropropanols can cause acute toxicity at high concentrations, it is extremely unlikely that this could occur through consumption of contaminated food, and it is the effect of low doses over a long time that is of most concern from a food safety point of view.
  • Chloropropanols have been shown to be carcinogenic in animal studies and are therefore potential human carcinogens.


  • The mechanism for chloropropanol production in acid-HVP is known to be a reaction between hydrochloric acid (HCl) and lipids.
  • The reaction occurs more rapidly at the high temperatures used in processing.
  • In bread and other baked products, chloropropanols are thought to be formed by a reaction during the baking process between the chloride in added salt and glycerol from flour and yeast.
  • In other foods, the mechanisms of chloropropanol production are unclear.

Stability in Foods

  • Chloropropanols are relatively non-volatile and may be quite persistent in foods once formed.

Control Options

  • The control of chloropropanols in foods focuses on limiting their production during processing.
  • This has been achieved by a number of changes to the manufacturing process.
  • replacing acid hydrolysis with an enzymatic process
  • reducing lipid concentrations in the raw materials
  • effective control of the acid hydrolysis process
  • use of an over-neutralisation treatment with NaOH to remove chlorohydrins after acid hydrolysis.


  • What is Furan?
  • Furan is a volatile heterocyclic organic chemical often found as an intermediate in industrial processes for producing synthetic polymer materials.
  • It is a very different compoud from the diverse group of chemicals sometimes referred to collectively as ‘‘furans’’, which includes various antimicrobials (nitrofurans) and dioxin-like toxins.
  • Concern over furan in foods dates back only to 2004, when a Food and Drug Administration (FDA) survey of heat-processed foods in the USA revealed that low levels of furan could be found in an unexpectedly large proportion of products processed in closed containers, such as cans and jars.
  • Furan is a possible human carcinogen, and therefore, even low levels in foods are undesirable.

Occurrence in Foods

  • Detectable levels of furan have now been found in:
  • Coffee
  • Canned fruits
  • Juices
  • Canned vegetables
  • Ready-to-use gravies
  • Breakfast cereals
  • Canned beans
  • Soups
  • Sauces

Effects on Health

  • Furan is cytotoxic and the liver is the target organ for acute toxic effects.
  • However, it is the effect of prolonged dietary exposure to furan and its possible carcinogenic potential that is of concern for food safety.
  • For this reason, it has been classified by the International Agency for Research on Cancer (IARC) as ‘‘possibly carcinogenic to humans.’’


  • It is thought probable that furan is a by-product of the high temperatures involved in the heat processing of foods, but the means by which it is produced is not known.
  • Proposed sources of furan formation include:
  • Thermal degradation of reducing sugars alone, or in combination with amino acids
  • Thermal degradation of some amino acids
  • Thermal oxidation of ascorbic acid, poly unsaturated fatty acids and carotenoids
  • The presence of furan residues in canned foods is probably a consequence of the volatile compound being trapped in the container.

Stability in Foods

  • There is little data as yet on the stability of furan in food, although it is a highly volatile compound and is likely to be driven off quite quickly if foods are :

“Cooked or reheated in open vessels”



  • As yet there is no legislation limiting levels of furan in foods.
  • Any future regulation will be based on the results of ongoing risk-analysis activities.