Biomedical Engineering Reference
In-Depth Information
presence on foods can cause serious illness. In fact, norovirus is the number one
foodborne pathogen in Canada and the USA, while in Europe it is among the top
three pathogens. Other viruses such as hepatovirus, astrovirus, and enterovirus and
others have also been associated with foodborne illness (Vasickova et al.
2005
). In
addition, some viruses, e.g., norovirus, are highly infectious and can lead to second-
ary cases and widespread outbreaks (Vega et al.
2014
).
2.2.3
Parasites
Parasites are another biological organism that can cause foodborne illness. These
organisms often have complicated life cycles, which can involve numerous hosts
before they infect humans. With the increase in globalization, a growing number of
foodborne parasites have emerged as new agents causing foodborne illness
(Robertson et al.
2013
). Recent work done by the FAO/WHO to prioritize food-
borne parasites, ranked the top foodborne illness associated parasites, as follows;
Taenia solium
,
Echinococcus granulosus
,
E. multilocularis
,
Toxoplasma gondii
and
Cryptosporidium
(FAO
2012
).
2.3
How Food Can Become Contaminated at Retail
While food can become contaminated at any stage of the farm-to-fork continuum,
this chapter will focus on the major sources of contamination which can occur at the
retail level. The intrinsic factors which can affect pathogen survival are outlined in
Table
2.2
.
Table 2.2
Intrinsic factors affecting the survival and growth of some foodborne bacterial
pathogens
Pathogen
Temperature
pH
Water activity (
a
w
)
Campylobacter
Optimum 42 °C,
range 32-45 °C
Optimum 6.5-7.5,
range 4.5-9.5
Optimum growth
a
w
= 0.997
Listeria
monocytogenes
Optimum 30-37 °C,
range −1.5 to 45 °C.
Optimum 6.5-7.5,
range 4.0-9.6
Optimum growth
a
w
= 0.90
Salmonella
(nontyphi)
5.2-46.2 °C,
optimum 35-43 °C
Range 3.8-9.5
optimum, 7-7.5
Min 0.93
Max >0.99
Optimum 0.99
Escherichia coli
(O157)
Optimum 37 °C, min
7-8 °C, max 46 °C
Optimum 6-7,
range 4.4-10.0
Optimum growth
a
w
= 0.99
Min
a
w
= 0.95
Vibrio
parahaemolyticus
20-35 °C; it can
grow at temperatures
up to 41 °C
Optimum 7.8-8.6;
range 4.8-11
a
w
range is 0.94-0.99,
with an optimum of
0.98
