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Contaminants Produced During
 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.
 Polyacrylamide is widely used in various applications, such
 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:
o Biscuits
o Bread
o toasted breakfast cereals
 Acrylamide is 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).’’
 Sources
 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 acrylamide produced
appear to be;
 amount of free asparagine present 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 decrease significantly in crisps or baked cereal
products during shelf life
 decrease significantly in 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.
 2-Processing
 The main factors that can be modified to minimize acrylamide
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.
 Legislation
 Acrylamide is not yet covered specifically by legislation in
Europe or North America and no permitted limits have been
 Benzene
 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 containing no 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.
 Sources
 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
 This may be why benzene 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
 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.
 Legislation
 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
 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.
 Chloropropanols
 What are Chloropropanols?
 The chloropropanols are a group of related chemical
contaminants that may be produced in certain foods during
 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 chloropropanols have 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.
 Sources
 The mechanism for chloropropanol production in acid-HVP
is known to be a reaction between hydrochloric acid (HCl) and
 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
 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.
 Furan
 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 heatprocessed 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.’’
 Sources
 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
 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”
 Legislation
 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.
 Reference: Lawley R., Curtis L. and Davis J. The food
safety hazard guidebook. RSC Publishing.