BLBS102-c43 BLBS102-Simpson March 21, 2012 14:30 Trim: 276mm X 219mm Printer Name: Yet to Come
43 Biogenic Amines in Foods 823and dimethyltryptamine (Jones 1983). There are also synthetic
counterparts of tryptamines, and these include the drug suma-
triptan and its derivatives used to treat migraines (Yen and Hsieh
1991).
NE or NA is synthesized in the adrenal medulla and the neu-
rons of the sympathetic nervous system from tyrosine via sev-
eral enzyme-catalyzed reactions including hydroxylation fol-
lowed by decarboxylation to dopamine and a final oxidation
step. The enzymes involved in the reactions are tyrosine hydrox-
ylase, DOPA decarboxylase, and dopamineβ-hydroxylase, re-
spectively (Aston-Jones et al. 2002). The NE (or NA) compound
serves multifunctions, as a stress hormone, a neurotransmitter,
and as a drug. As stress hormone, it is involved in triggering
responses such as increasing heart rate, facilitating release of
glucose from storage depots, and increasing blood flow to the
skeletal muscle; as a neurotransmitter, it is released in the brain
to mitigate inflammations; and as a drug, it can increase vascular
tone and blood pressure.
Epinephrine or adrenaline is synthesized in the adrenal gland
from the amino acids phenylalanine and tyrosine via a series of
intermediates (Fig. 43.3). In the first step, tyrosine is oxidized
tol-DOPA, followed by decarboxylation to dopamine, which
is subsequently oxidized to NE and then methylated to form
adrenaline or epinephrine. It functions both as a hormone and as
a neurotransmitter and carries out manifold functions in the body.
For instance, it increases heart rate, modulates dilation of blood
vessels and air passages, and participates in the fight/flight re-
sponse of the sympathetic nervous system. It also participates in
the contraction of the smooth muscles; inhibits insulin secretion
while enhancing glucagon secretion in the pancreas; and also
stimulates glycolysis in the muscle, lipolysis in adipose tissues,
and glycogenolysis in the liver and the muscle (Cannon 1929).
Dopamine, also known as 4,2-aminoethyl benzene-1,2-diol,
has a molecular formula of C 6 H 3 (OH) 2 (CH 2 ) 2 NH 3. It is syn-
thesized by nervous tissues and the adrenal medulla from tyro-
sine (l-Tyr) by hydroxylation to form dihydroxyphenyl alanine
(l-DOPA) in a reaction catalyzed by tyrosine hydroxylase, fol-
lowed by a decarboxylation step catalyzed by DOPA decar-
boxylase (Fig. 43.3). Dopamine thus formed may be processed
further into NE by the enzyme dopamineβ-hydroxylase and
then methylated into epinephrine (Fig. 43.3). Dopamine is in-
volved in motivation, addictions, behavioral manifestations, and
coordination of bodily movements (Yen and Hsieh 1991).
Other commonly known biogenic amines and their precur-
sors include cadaverine, agmatine,β-phenylethylamine, and
putrescine derived, respectively, from lysine, arginine, pheny-
lalanine, and ornithine. Polymerization of putrescine forms the
polyamines spermine and spermidine (Pegg and McCann 1982).
These polymeric products are highly resistant to degradation
during processing and are capable of withstanding procedures
like canning, freezing, smoking, and cooking (Etkind and Wil-
son 1987). Some biogenic amines are present at low levels in
fresh foods; however, these levels may increase via microbial
decarboxylation of free amino acids during processes such as
fermentation, storage, and in food spoilage. Various factors such
as pH, temperature, salt concentration, and glucose availability
all influence the formation of biogenic amines in foodstuffs.The importance of biogenic amines to the food industry is due
to two main reasons. First, if ingested in high quantities, they
may induce toxic effects. For example, consumption of tyra-
mine and histamine has been associated with disorders such as
a burning sensation in the throat, flushing, headaches, nausea,
hypertension, numbing and tingling of the lips, rapid pulse, and
vomiting (De Vries 1996). Certain biogenic amines have also
been implicated in the formation of carcinogenic nitrosamines,
and the variation in biogenic amine levels has been suggested as
a useful chemical indicator of food quality or spoilage. Thus, the
food industry has developed several techniques for determining
biogenic amine concentrations in food products for various pur-
poses, including research, health and safety, or quality control.
The effects of food processing on biogenic amine formation or
levels have also been extensively studied in order to develop
methods of limiting biogenic amine formation in food products
(Stratton et al. 1991, Shalaby 1996). Because of its potential
health concerns, governments and related regulatory agencies
have established legal limits and recommendations for these
compounds in certain products (FDA 2001).Basic Structure and FormationBiogenic amines may be classified into three main groups based
on their molecular structures as aliphatic, aromatic, and hetero-
cyclic. Examples of aliphatic biogenic amines include methy-
lamine, dimethyl amine, ethylamine, diethyl amine, butyl amine,
cadaverine, putrescine, spermidine, and spermine; examples of
the aromatic amines are tyramine, octapamine, dopamine, and
synephrine; and examples of the heterocyclic biogenic amines
are 2-amino-2-methylimidazolo[4,5-f]quinolone (IQ), 2-amino-
3,8-dimethylimidazo[4,5-f]quinoxaline and 2-amino-1-methyl-
6-phenylimidazo[4,5-b]pyridine (Fig. 43.1).
Biogenic amines may be formed endogenously during normal
metabolic processes in living cells from the degradation of bio-
logical molecules like proteins and/or decarboxylation of certain
amino acids (e.g., tyrosine, phenylalanine, arginine, and histi-
dine) by microbial enzymes. Endogenous amines formed from
cellular metabolism play a plethora of important roles within
the cardiovascular, nervous, and digestive systems. They are
produced in many different tissues, for example, adrenaline is
produced in the adrenal medulla, while histamine is formed
in mast cells and liver and is subsequently transmitted locally
or via the blood stream to perform various functions as in the
modulation of growth and proliferation of eukaryotic cells by
spermine and spermidine (Pegg and McCann 1982). Biogenic
amines may also be formed exogenously as intermediates in
the chemical and pharmaceutical industries, or released into the
atmosphere from livestock breeding operations, animal feeds,
waste treatment/incineration, and in automobile exhaust fumes.
The exogenous biogenic amines are directly absorbed in the
intestine, a process that is enhanced by intake of alcohol.
The amino acid decarboxylase enzymes of microorganisms
carry out the dual functions of producing the biogenic amines
for normal functions in the organism or removing the substrate
(parent amino acid) to prevent the excessive accumulation of
these substrate molecules. Several of the decarboxylase enzymes