Bacterial Pathogens, Mycotoxins, Viruses, Parasites, and Fish Toxins ◾ 397
Detection Methods 16,17
Several methods have been studied to detect mycotoxins and, more particularly, aflatoxins in
food. These include solvent extraction of a suspected food sample, thin layer chromatographs of
the extract, high pressure liquid chromatography (HPLC), and visualizing it under a UV light or a
fluorescent light. Chemical tests and analysis by mass spectral methods are used for identification
of the specific type of mycotoxins. In recent years, immunoassays and immunosensors are used for
rapid and sensitive detection of mycotoxins from food (see Chapter 42).
Biogenic Amines
Different types of amines can form in many protein-rich foods by the decarboxylation of amino
acids by the specific amino acid decarboxylases of microorganisms. Some of these amines are biologically active and cause illness when consumed in considerable amounts. Examples of biogenic
amines are histamine (produced from l-histidine), putrescine, cadaverine (breakdown of lysine
by lysine decarboxylase), and tyramine (produced from l-tyrosine). Many bacteria found in foods
can produce very active histidine or tyrosine decarboxylases and, if free l-histidine and l-tyrosine
are present, can convert them to histamine and tyramine, respectively. Some food spoilage bacteria and even several lactobacilli can have very active histidine and tyrosine decarboxylases. The
protein-rich foods associated with biogenic amine poisoning include cheeses ripened for a long
time, mold-ripened cheeses, fermented sausages stored for a long time, and different types of fish.
Histamine poisoning of fish origin also called scombriod poisoning is further discussed under fish
and shellfish toxins.
toxins Associated with Fish and Shellfish 18–21
Fish and shellfish are responsible for food poisoning as a result of the consumption of varieties of
toxins originating from harmful species of algae from marine, brackish, and fresh-water environments. Fish accumulates toxins upon feeding on toxic algae, and the increased consumption of
fish and shellfish has resulted in large numbers of food poisoning cases. Toxins are of two types:
diarrheagenic and neurotoxic, and they are commonly classified as paralytic shellfish poisoning
(PSP), diarrhetic shellfish poisoning (DSP), neurotoxic shellfish poisoning (NSP), ciguatera fish
poisoning (CFP), azaspiracid shellfish poisoning (AZP), and amnesiac shellfish poisoning (ASP)
(Table 28.2). In addition, scombroid toxin, which results from bacterial breakdown of fish proteins, also causing severe allergic response are also discussed.
Scombroid Poisoning
Scombroid poisoning, also known as histamine fish poisoning, is an allergy-like form of food
poisoning and was initially recognized to occur from the ingestion of spoiled fish of scombroid
groups (tuna, mackerel, and bonito). However, it is now recognized that the illness can occur from
the consumption of other types of spoiled fish, such as mahi mahi, bluefish, yellowtail, amberjack, herring, sardines, and anchovies. Most of these fish have a high level of free l-histidine in
their tissues. In addition, the breakdown of muscles by autolytic proteases and bacterial proteases
produced during their growth in fish release histamine. Histidine decarboxylase produced by
Detection Methods 16,17
Several methods have been studied to detect mycotoxins and, more particularly, aflatoxins in
food. These include solvent extraction of a suspected food sample, thin layer chromatographs of
the extract, high pressure liquid chromatography (HPLC), and visualizing it under a UV light or a
fluorescent light. Chemical tests and analysis by mass spectral methods are used for identification
of the specific type of mycotoxins. In recent years, immunoassays and immunosensors are used for
rapid and sensitive detection of mycotoxins from food (see Chapter 42).
Biogenic Amines
Different types of amines can form in many protein-rich foods by the decarboxylation of amino
acids by the specific amino acid decarboxylases of microorganisms. Some of these amines are biologically active and cause illness when consumed in considerable amounts. Examples of biogenic
amines are histamine (produced from l-histidine), putrescine, cadaverine (breakdown of lysine
by lysine decarboxylase), and tyramine (produced from l-tyrosine). Many bacteria found in foods
can produce very active histidine or tyrosine decarboxylases and, if free l-histidine and l-tyrosine
are present, can convert them to histamine and tyramine, respectively. Some food spoilage bacteria and even several lactobacilli can have very active histidine and tyrosine decarboxylases. The
protein-rich foods associated with biogenic amine poisoning include cheeses ripened for a long
time, mold-ripened cheeses, fermented sausages stored for a long time, and different types of fish.
Histamine poisoning of fish origin also called scombriod poisoning is further discussed under fish
and shellfish toxins.
toxins Associated with Fish and Shellfish 18–21
Fish and shellfish are responsible for food poisoning as a result of the consumption of varieties of
toxins originating from harmful species of algae from marine, brackish, and fresh-water environments. Fish accumulates toxins upon feeding on toxic algae, and the increased consumption of
fish and shellfish has resulted in large numbers of food poisoning cases. Toxins are of two types:
diarrheagenic and neurotoxic, and they are commonly classified as paralytic shellfish poisoning
(PSP), diarrhetic shellfish poisoning (DSP), neurotoxic shellfish poisoning (NSP), ciguatera fish
poisoning (CFP), azaspiracid shellfish poisoning (AZP), and amnesiac shellfish poisoning (ASP)
(Table 28.2). In addition, scombroid toxin, which results from bacterial breakdown of fish proteins, also causing severe allergic response are also discussed.
Scombroid Poisoning
Scombroid poisoning, also known as histamine fish poisoning, is an allergy-like form of food
poisoning and was initially recognized to occur from the ingestion of spoiled fish of scombroid
groups (tuna, mackerel, and bonito). However, it is now recognized that the illness can occur from
the consumption of other types of spoiled fish, such as mahi mahi, bluefish, yellowtail, amberjack, herring, sardines, and anchovies. Most of these fish have a high level of free l-histidine in
their tissues. In addition, the breakdown of muscles by autolytic proteases and bacterial proteases
produced during their growth in fish release histamine. Histidine decarboxylase produced by