Handbook of Meat Processing

470 Chapter 27

nitrous acid (pKa = 3.36). The amount of

N - nitrosamines in meat products depends

on many variables, such as the amount of

added and residual nitrite, processing condi-

tions, the amount of lean meat in the product,

heating if any, and the presence of catalysts

or inhibitors (Hotchkiss and Vecchio 1985 ;

Walker 1990 ). A database with the nitrosa-

mine content in 297 food items from 23

countries was recently created with the aim

of facilitating the quantifi cation of dietary

exposure to potential carcinogens and their

relation to certain types of cancer (Jakszyn

et al. 2004 ).

There was intense discussion in the 1970s

about residual nitrite in cured meats and the

generation of N - nitrosamines in certain cured

meat products. The generation rate of nitro-

samines depends on many variables, such as

the amount of remaining nitrite, presence of

nitrosation catalysts or inhibitors, the pro-

cessing temperature, pH of the product,

time, storage conditions, and the addition of

reducing substances like ascorbate or iso-

ascorbate. The presence of microorganisms

able to generate nitrite from nitrate via nitrate

reductase activity or able to produce amines

molecular weight and more polar, have
also been reported. Some of the most
important are N - nitrosoaminoacids, such as
N - nitrososarcosine and N - nitrosothiazo-
lidine - 4 - carboxylic acid; hydroxylated N -
nitrosamines; N - nitroso sugar amino acids;
and N - nitrosamides, such as N - nitrosoureas,
N - nitrosoguanidines, and N - nitrosopeptides
(Pegg and Shahidi 2000 ).
Nitrite is the main additive used as a pre-
servative in cured meats because of its pow-
erful inhibition of the outgrowth of spores of
putrefactive and pathogenic bacteria such as
Clostridium botulinum. Nitrite has other
additional advantages, including the genera-
tion of nitrosylmyoglobin that gives the
typical pink cured color formation and its
contribution to the oxidative stability of
lipids and indirectly to cured meat fl avor
(Ramarathnam 1998 ).
However, the main concern is related to
the residual nitrite remaining in the meat
product, because it can be a source of nitrous
acid and thus of nitrosamines if secondary
amines are also present (Toldr á et al. 2009 ).
The amount of nitrous acid increases when
the pH of the product approaches the pKa of

Table 27.1. Potential sources of exposure to contaminants and conditions affecting their presence
in meat and processed meat

Group of compounds Exposure source Conditions affecting

Nitrosamines Cured meats Available residual nitrite in cured meats with

presence of secondary amines and catalyzed by

temperature

Biogenic amines Fermented meats or

non - hygienic meats

Hygiene and/or type of microbial fl ora:

decarboxylation of certain amino acids

Heterocyclic amines Cooked meats at high

temperature

Type of cooking of meat, heating temperature and

time

Polycyclic aromatic

hydrocarbons

Smoked meats Smoking, especially traditional smoking at high

temperature for long time.

Smoke fl avorings if not adequately treated

Lipid oxidation Cooked or processed

meats

Chemical reactions during storage or processing

catalyzed by oxygen, salt, hydrogen peroxide,

radiations, lypoxigenase, temperature.

Protein oxidation Cooked or processed

meats

Chemical reactions during processing catalyzed by

oxygen reactive species and temperature

Veterinary drugs All meats Intentional addition to feed or water given to animals

Growth promoters All meats Intentional addition to feed or water given to animals

Environmental

contaminants

All meats Contaminants already present in primary ingredients

formulated in feeds given to animals