472 Chapter 27
formed in oven roasting and baking at low
temperatures. In general, the direct contact of
meat with the heating source facilitates the
formation of higher levels of HAs than when
the meat is in less intimate contact with the
heating device.Polycyclic Aromatic
Hydrocarbons ( PAH )
Smoking has been used for centuries as a
means of meat preservation and more recently
it has been mainly used for its sensory effects
on the meat. It has traditionally consisted
in the exposure of meat products to the
smoke generated by controlled combustion
of certain natural hard woods, sometimes
accompanied by aromatic herbs and spices.
The pyrolysis of wood generates smoke
through different oxidation routes. Moist
wood chips can also be used for direct gen-
eration of smoke. The smoke is condensed
and adsorbed on the surface of the meat
product. The penetration rate into the product
depends on the conditions of the process
(temperature, humidity, volatility, and veloc-
ity of the smoke). Further information on
smoking, its production and application as
well as its sensory and antimicrobial effects
on meat, may be read in chapter 12.
There are some fl avoring substances that
exert typical smoke fl avor, but the smoke
may also contain some health - hazardous
compounds like polycyclic aromatic hydro-
carbons (PAH), phenols, and formaldehyde
(Bem 1995 ). Polycyclic aromatic hydrocar-
bons are generated during the thermal decom-
position of the wood (over 500 ° C) when
oxygen is limited (Simko 2009a ). The most
important polycyclic aromatic hydrocarbons
are listed in Table 27.2. Some polycyclic
aromatic hydrocarbons, especially benzo - a -
pyrene, are known to possess cancer - induc-
ing and carcinogenic properties. Most of the
PAH have been classifi ed as 2A by the
International Agency of Research on Cancer.
Information about PAH content in 313 foodWays to control amine generation are
based on the use of starter cultures unable to
produce amines but competitive against
amine - producing microorganisms; the use of
microorganisms having amine oxidase activ-
ity; the selection of raw materials of high
quality; and good manufacturing practices
(Talon et al. 2002 ; Vidal - Carou et al. 2007 ).
The analysis of biogenic amines includes
a liquid extraction with acid solutions or
organic solvents followed by cleanup of the
extract. Amines are then analyzed by high
performance liquid chromatography with
either ion - exchange or reverse - phase, with
ion pairs followed by ultraviolet - visible or
fl uorescence detection. Amines are usually
derivatized either pre - or post - column (Vidal -
Carou et al. 2009 ).
Heterocyclic Amines
These amines are formed by the reaction of
amino acids, alone or with creatine or creati-
nine, under high heating such as that achieved
in certain types of meat cooking. The main
two classes of heterocyclic amines (HAs)
are aminoimidazol - quinolines and amino-
imidazol - pyridines. The exposure to HAs
is mostly due to 2 - amino - 1 - methyl - 6 -
phenylimidazol(4,5,b)pyridine (PhIP) and
2 - amino - 3,8 - dimethylimidazo(4,5,f)quinoxi-
line (MeIQx). Other minor compounds
are 2 - amino - 9 - H - pyrido(2,3,b)indole (AC);
2 - amino - 3,4 - dimethylimidazo(4,5,f)quino-
line (IQ); and 2 - amino - 3,4,8 - trimethylimi-
dazo(4,5,f)quinoxiline (DiMeIQx) (Jakszyn
et al. 2004 ). All these amines are closely
related to the development of certain types of
cancer (Bogen 1994 ; Augustsson et al. 1999 ).
The assessment of the intake of AHs is dif-
fi cult because its content in meat depends on
the type of cooking, temperature, and time
(Bjeldanes et al. 1983 ). Frying, broiling, and
grilling/barbecuing are the cooking methods
that produce the largest amounts of HAs
because of the very high temperatures used
(Sinha et al. 1998 ). Lower levels of HAs are