Download acrylamide: a chemical toxic generated during heat

Recibido 25/11/2011, Aceptado 30/11/2011, Disponible online 22/12/2011
ACRYLAMIDE: A CHEMICAL TOXIC GENERATED DURING HEAT
PROCESSING OF STARCHY FOODS
Franco Pedreschi1*
1
Departmento de Ingeniería Química y Bioprocesos, Pontificia Universidad
Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile, e-mail:
[email protected]
*
ASIS-UC: Interdisciplinary Research Program on Tasty and Healthy Foods.
Pontificia Universidad Católica de Chile Casilla 306 Correo 22. Santiago Chile
Acrylamide
Acrylamide is an odorless and colorless
crystalline solid with a melting point of
84.5 °C that is formed from the hydration
of acrylonitrile. Such a small compound is
soluble en water, acetone, and ethanol, has
a high mobility in soil and groundwater
and is biodegradable. Before its discovery
in foods, acrylamide was known as an
industrial chemical and a component of
cigarette smoke. Acrylamide, a potential
genetic and reproductive toxin with
mutagenic and carcinogenic properties in
experimental mammalians in both in vitro
and in vivo study, has been found in a
large range of carbohydrate-rich foods
processed at high temperatures, which has
attracted worldwide concern. On the other
hand, acrylamide is considered as
probably carcinogenic to humans (Casado
et al., 2010). It has been claimed that
dietary acrylamide does not constitute any
risk to human health (Jung et al. 2003;
Carrieri et al. 2009). However,
considering the potential health hazard of
this molecule and its wide distribution in
the Western diet, numerous studies have
been undertaken to provide reliable
mitigation strategies to minimize its levels
in processed products (Jung et al. 2003;
Carrieri et al. 2009). Besides, acrylamide
can penetrate into breast milk and the
human placenta. Based on their results,
Sörgel et al. (2002) advised that pregnant
and
breast-feeding
mothers
omit
acrylamide-containing food until the
individual sensitivity to acrylamide is
known.
Acrylamide is formed during thermal
processing in carbohydrate-rich and
protein-low plant foods at high
temperatures and low moisture conditions
associated with frying, baking, and
roasting (Tareke et al., 2000). There are
many reports about how to reduce
acrylamide formation in foods, including
selecting foodstuffs, removing acrylamide
precursors,
adapting
processing
conditions, and adding food ingredients
(Ou et al., 2010). In April 2002, Swedish
researchers shocked the food safety world
when they presented preliminary findings
of acrylamide in some fried and baked
foods, most notably potato chips and
French fries, at levels of 30-2300 m/kg.
As acrylamide has not been detected in
unheated or boiled foods, it was
considered to be formed during heating at
high temperatures. Research up to date
shows that acrylamide formation in
starch-based foods (such as potato chips,
French fries, bread and breakfast cereals,
cookies and crackers) takes place via
Vol 20, No 24 (2011), Revista Alimentos Hoy - 3
Maillard reaction upon heating above 120
°C (Friedman 2003; Mottram and others
2002; Stadler et al., 2002). They attributed
this fact to the higher temperatures
reached in Maillard nonenzymatic
browning reactions required for desirable
color, flavor and aroma production. The
data published so far indicate that a
temperature >120°C is required for
acrylamide formation.
An interesting example of how the
exposure of acrylamide from coffee is
found to contribute substantially to the
total dietary acrylamide exposure in
Norway is shown. Dybing and Sanner
(2003) estimated that the daily mean
intake of acrylamide from foods and
Importance of acrylamide in heated
processed foods
Currently, a substantial body of research
has been carried out world-wide to build
greater understanding of how acrylamide
is formed in high-temperature processed,
what the risks are for consumers and how
to reduce occurrence levels. For instance,
Maillard reaction has been identified as the
major mechanism of acrylamide formation
in fried potatoes and at the same time is
responsible of the desirable flavour, odour,
colour, texture and taste attributes of the
fried potatoes. So, producing French fries
or potato chips with low levels of
acrylamide without affecting the sensorial
properties of the final product is a major
challenge for fried potato manufacturers.
The presence of acrylamide in nearly all
fried, baked, and roasted carbohydrate rich
foods has been confirmed in many studies
performed all over the world. Browned
crispy crusts in foods like French fries,
potato chips, crackers, pretzel-like snacks,
cereals, and browned breads tend to have
the highest levels of acrylamide.
coffee was to be 0.49 and 0.46 g kg−1
body weight in Norwegian males and
females, respectively. These authors
estimated the Norwegian daily intake
level of acrylamide from foods for 70
years in males to correspond to a lifetime
cancer risk of 0.6 × 10−3, implying that 6
out of 10000 individuals may develop
cancer due to acrylamide. Finally, a Swiss
total diet study of acrylamide in the diet of
14 men and 13 women showed that coffee
contributed 36% of the total acrylamide
intake. Recently, the US Food and Drugs
Administration (FDA) reported levels of
acrylamide in brewed coffee from 6 to 16
g l−1 (Andrzejewski et al. 2004).
Concentrations of acrylamide present in
heated foods are the result of
simultaneously occurring formation and
elimination mechanisms (Gökmen &
Senyuva, 2006a). Finally, this significant
variability of acrylamide levels in foods
becomes important when considering
dietary exposure to acrylamide.
Acrylamide mitigation in heated
processed foods
For heat processed food industry it is not
only important to know the principal
mechanism(s) of acrylamide formation but
also several acrylamide mitigation
procedures reported in the literature that
could be very useful for heated food
manufacturers in order in reduce to
reasonable
levels
the
acrylamide
generation in their processing lines.
Maillard reaction is believed to be the
main route for acrylamide formation
between reducing sugars (glucose and
fructose), sucrose, and the amino acid
asparagine, and, consequently, a variety of
Vol 20, No 24 (2011), Revista Alimentos Hoy - 4
technologies have been developed to
reduce acrylamide concentration in
thermally processed foods based either on:
(i) Changing process parameters (e.g. time
and temperature of cooking) which inhibits
Maillard
Reaction;
(ii)
Reducing
acrylamide precursor levels in raw
materials to be cooked at high
temperatures
(e.g.
by
using
microorganisms, asparaginase, amino
acids and saccharides, blanching, etc.). At
the same time, food heating has many
advantages since it adds taste, color,
texture and minimizes harmful germs,
among others. Flavor and aroma
compounds are produced via the Maillard
reaction, where various hazardous
compounds may form as well, such as
acrylamide (Mottram et al., 2002). Most
of recent research for acrylamide reduction
in foods processed at high temperatures
will be mentioned and in order to develop
new mitigation techniques for acrylamide
in different food matrixes.
The reduction of acrylamide precursor
levels in raw materials is another strategy
used to reduce acrylamide formation in
heat-processed foods and various pretreatments have been developed such as:
(i) By using food grade microorganisms;
(ii) By using the enzyme asparaginase; (iii)
By using amino acids; (iv) By using non
reducing sugars; (v) By using genetic
modification. On the other hand, it is also
possible to mitigate acrylamide formation
in high temperature processed foods by
changing the processing parameters. In this
way, cooking, methods and equipment,
food material, and pre-treatment unit
operations that modify process parameters
can significantly diminish the acrylamide
amount in heat processed foods (up to
90%), maintaining intact their sensorial
attributes (Mariotti et al., 2011). For
instance, some results have shown that
vacuum frying may be a mitigation
alternative process for producing fried
products with lower amounts
acrylamide (Lindsay et al., 2005).
of
By changing some parameters of food
processing such as time, temperature,
pressure and pH; it would be possible to
diminish the acrylamide content of hightemperature processed foods. In this sense,
some authors have developed acrylamide
mitigation technologies based on lowering
the pH of the food products. They have
studied the effect of pH on acrylamide
formation concluding that the dependency
of acrylamide formation exhibited a
maximum around at pH value of 8. Lower
pH
values
enhanced
acrylamide
elimination and decelerated its formation
(Low et al., 2006; Mestdagh et al., 2008).
Another acrylamide mitigation approach
has been the use of cations, in this respect
different studies have shown that the
addition or divalent or trivalent cations
effectively reduce the amount of
acrylamide thermally processed food
(reduction up to 90 %) while minimally
affecting its sensorial desirable attributes
(Lindsay et al., 2005).
Finally, acrylamide mitigation in high
temperature processed foods could be
reached by combining several techniques
previously mentioned. Some authors have
considered that the combination of several
methods could be the best option for
reducing acrylamide formation in heat
processed foods. The main strength of this
approach appears to be that the final
products could preserve better their
original and desirable sensorial attributes
because of it is possible to decrease the
intensity and duration of each treatment
alone.
Vol 20, No 24 (2011), Revista Alimentos Hoy - 5
CONCLUSIONS
Acrylamide is a toxic compound with
mutagenic and carcinogenic properties in
experimental mammalians which has been
found in several carbohydrate foods
processed at high temperatures. Nowadays,
most available information regarding to
acrylamide formation in foods is attributed
to the Maillard reaction in which the
reducing sugars react with asparagine
when the food is heated. There is an urgent
need to reduce the content of dietary
acrylamide in order to prevent adverse in
ACKNOWLEDGMENTS
Authors acknowledge financial support
from FONDECYT Projects 1110510.
REFERENCES
Andrzejewski, D., Roach. J., Gay, M.,
Musser, S. 2004. Analysis of coffee for
the presence of acrylamide by LCMS/MS. Journal of Agriculture and Food
Chemistry, 52, 1996-2002.
Carrieri G., De Bonis, M.,
Pucciarelli, A., Ruocco,
Modeling and validation
acrylamide formation in a
during frying. Journal
Engineering, 95, 90–98
Pacella, C.,
C. 2009.
of local
model food
of Food
Casado, F. J., Sánchez, A. H., Montaño,
A. 2010. Reduction of acrylamide content
of ripe olives by selected additives. Food
Chemistry, 119, 161-166.
Dybing and Sanner 2003. Risk
Assessment of Acrylamide in Foods.
Toxicological Sciences, 75, 7-15.
vivo effects in human beings. On the other
hand, attempts to determine a possible
involvement of dietary acrylamide in
human cancers have not been conclusive.
Recently published data have suggested
that there are associations between dietary
acrylamide exposure and risk of cancer but
only at certain places. These issues have
prompted scientists to develop a wide
range of methods for acrylamide
mitigation. These technologies have been
also effective not only as an alternative for
reducing acrylamide but also for
maintaining the desirable sensorial
attributes of foods.
Friedman,
M.
2003.
Chemistry,
biochemistry, and safety of acrylamide. A
review. Journal of Food Agriculture and
Chemistry, 51, 4504–4526.
Gökmen, V., Şenyuva, H.Z. 2006. Study
of colour and acrylamide formation in
coffee, wheat flour and potato chips
during heating. Food Chemistry, 2006,
99:238–43.
Jung, M.Y., Choi, D.S., Ju, J.W. 2003. A
novel technique for limitation of
acrylamide formation in fried and baked
corn chips and in French fries. Journal of
Food Science, 68, 1287–1290.
Lindsay, R.C., & Jang, S.J. 2005.
Chemical intervention strategies for
substantial suppression of acrylamide
formation in fried potato products.
Advances in Experimental Medicine and
Biology, 561, 393-404.
Low, M.Y., Koutsidis, G., Parker, J.,
Elmore S., Dodson, A., Mottram, D. 2006.
Effect of Citric Acid and Glycine
Addition on Acrylamide and Flavor in a
Potato Model System. Journal of
Vol 20, No 24 (2011), Revista Alimentos Hoy - 6
Agricultural and Food Chemistry, 54,
5976–5983.
Mestdagh, F., Maertens, J., Cucu, T.,
Delporte, K., Van Peteghem, C., De
Meulenaer, B. 2008. Impact of additives
to lower the formation of acrylamide in a
potato model system through pH
reduction and other mechanisms. Food
Chemistry, 107, 26–31.
Mariotti, S., Pedreschi, F., Carrasco, J.,
Granby, K. 2011. Patented Techniques for
Acrylamide
Mitigation
in
HighTemperature Processed Foods. Recent
Patents on Food, Nutrition & Agriculture,
3, 158-171
Mottram, D.S., Wedzicha, B.L., Dodson,
A.T. 2002. Acrylamide is formed in the
Maillard reaction. Nature, 419, 448-449.
Ou, S., Shi, J., Huang, C., Zhang, G.,
Teng, J., Jiang, Y., & Yang, B. 2010.
Effect of antioxidants on elimination and
formation of acrylamide in model reaction
systems. Journal of Hazardous Materials,
182, 863-868.
Sörgel, F., Weissenbacher, R., KinzigSchippers, M., Hofmann, A., Illauer, M.,
Skott, A., Landersdorfer, C. 2002.
Acrylamide: increased concentrations in
homemade food and first evidence of its
variable absorption from food, variable
metabolism and placental and breast milk
transfer in humans. Chemotherapy, 48,
267-74.
Tareke, E., Rydberg, P., Karlsson, P.,
Eriksson, S., Toernqvist, M. 2000.
Acrylamide: a cooking carcinogen?
Chemical research in Toxicology, 13,
517-522.
Stadler, R., Blank, I., Varga, N., Robert,
F., Hau, J.R., Guy, P., Robert, M.,
Riediker, S. 2002. Acrylamide from
Maillard reaction products. Nature, 419,
449-450.
Vol 20, No 24 (2011), Revista Alimentos Hoy -7