702 Modern Food Microbiology
in the study came from pigs infected with 250,000 T. spiralis, which produced around 1000 trichina
per gram of tissue compared to about 1 trichina per gram in naturally infected pigs. Although the
large number of trichinae per gram may have been a factor in their survival at the cooking procedures
employed, the inherent unevenness of cooking in microwave ovens is of concern. In another study,
whereas trichinae larvae were not inactivated at 77 or 82
◦ C in microwave ovens, cooking to an internal
temperature of 77
◦ C in a conventional convection oven, flat grill, charbroiler, or deep fat did inactivate
the larvae.
64 Further, infected larvae survived rapid cooking that involved thawing pork chops in an
industrial microwave oven followed by cooking on a charbroiler to 71 or 77
◦ C.
65
The cooking of pork in microwave ovens is clearly a matter of concern relative to the destruction of
trichinae larvae, and two factors may explain the greater efficiency of convection ovens over microwave
ovens. First, microwave cooking is rapid, and herein may lie the problem. Oven heat has been shown
to be more destructive to trichinae larvae in roasts when slow-cooked in conventional ovens at 200
◦ F
(93.3
◦ C) than when fast-cooked at 350
◦ F or 176.7
◦ C.
11 Second, a convection oven is more uniformly
heated than some microwave ovens. This is minimized if the product is rotated in the latter type ovens
or if the oven is equipped with an automatic rotating device. Otherwise, uneven heating occurs, leading
to undercooking of some parts of a roast while other parts may be overcooked. It has been shown that
a set of criteria that leads to consistent doneness of pork products in microwave ovens will result in
safe products.
106
Anisakiasis
This roundworm infection is caused by two closely related genera and species: Anisakis simplex
(the herringworm or whaleworm) and Pseudoterranova decipiens (formerly Phocanema; codworm
or sealworm). Both of these organisms have several intermediate hosts and generally more than one
definitive host. Humans are not final hosts for either, and human disease occurs as the result of humans
being accidental interlopers in the life cycles of these worms.
The definitive hosts are marine mammals—whales in the case of A. simplex and gray (and other)
seals in the case of P. decipiens. Feces of these animals contain thousands of eggs, which when they
enter water undergo their first molt (stage L1 to stage L2). The free-swimming larvae that result are
ingested by small crustaceans (copepods), and they, in turn, are ingested by larger crustaceans, which
serve as intermediate hosts during the second molt (stage L2 to L3). A final host may ingest L3 larvae
along with the crustacean intermediate, but more often, L3 is ingested by fish or squid, which may,
in turn, be ingested by larger fish before reaching the final host. The last two molts (L3 and L4) lead
to adults that mate, and these events take place in the final host. The infectious larva is L3, and it
is usually found in tight, flat coils in or on fish viscera, and some larvae may occur in the belly flap
muscles of fish. Because of its preference for whale hosts, A. simplex is found more often in fish from
the northern Pacific.
In the case of P. decipiens, eggs in seal feces are ingested by copepods, and L2- or early-L3-stage
larvae are ingested by the first intermediate host—fish. In fish, they penetrate the stomach wall, enter
the body cavity, and many burrow into fish muscles. In fish, the L3 larvae grow to 25–50 mm in length
and are red to brown in color. The final host, seals, tends to ingest the organisms principally from
smelt and other small fish.
Human infections occur upon the ingestion of fish that contain L3- and L4-stage larvae. Thus,
anisakids do not mature in humans. Disease symptoms arise from the activities of the juvenile worms.
A. simplex larvae are more harmful than those of P. decipiens because they often penetrate the mucosal
lining, whereas most P. decipiens larvae are passed in feces or are coughed up or vomited after irritating
in the study came from pigs infected with 250,000 T. spiralis, which produced around 1000 trichina
per gram of tissue compared to about 1 trichina per gram in naturally infected pigs. Although the
large number of trichinae per gram may have been a factor in their survival at the cooking procedures
employed, the inherent unevenness of cooking in microwave ovens is of concern. In another study,
whereas trichinae larvae were not inactivated at 77 or 82
◦ C in microwave ovens, cooking to an internal
temperature of 77
◦ C in a conventional convection oven, flat grill, charbroiler, or deep fat did inactivate
the larvae.
64 Further, infected larvae survived rapid cooking that involved thawing pork chops in an
industrial microwave oven followed by cooking on a charbroiler to 71 or 77
◦ C.
65
The cooking of pork in microwave ovens is clearly a matter of concern relative to the destruction of
trichinae larvae, and two factors may explain the greater efficiency of convection ovens over microwave
ovens. First, microwave cooking is rapid, and herein may lie the problem. Oven heat has been shown
to be more destructive to trichinae larvae in roasts when slow-cooked in conventional ovens at 200
◦ F
(93.3
◦ C) than when fast-cooked at 350
◦ F or 176.7
◦ C.
11 Second, a convection oven is more uniformly
heated than some microwave ovens. This is minimized if the product is rotated in the latter type ovens
or if the oven is equipped with an automatic rotating device. Otherwise, uneven heating occurs, leading
to undercooking of some parts of a roast while other parts may be overcooked. It has been shown that
a set of criteria that leads to consistent doneness of pork products in microwave ovens will result in
safe products.
106
Anisakiasis
This roundworm infection is caused by two closely related genera and species: Anisakis simplex
(the herringworm or whaleworm) and Pseudoterranova decipiens (formerly Phocanema; codworm
or sealworm). Both of these organisms have several intermediate hosts and generally more than one
definitive host. Humans are not final hosts for either, and human disease occurs as the result of humans
being accidental interlopers in the life cycles of these worms.
The definitive hosts are marine mammals—whales in the case of A. simplex and gray (and other)
seals in the case of P. decipiens. Feces of these animals contain thousands of eggs, which when they
enter water undergo their first molt (stage L1 to stage L2). The free-swimming larvae that result are
ingested by small crustaceans (copepods), and they, in turn, are ingested by larger crustaceans, which
serve as intermediate hosts during the second molt (stage L2 to L3). A final host may ingest L3 larvae
along with the crustacean intermediate, but more often, L3 is ingested by fish or squid, which may,
in turn, be ingested by larger fish before reaching the final host. The last two molts (L3 and L4) lead
to adults that mate, and these events take place in the final host. The infectious larva is L3, and it
is usually found in tight, flat coils in or on fish viscera, and some larvae may occur in the belly flap
muscles of fish. Because of its preference for whale hosts, A. simplex is found more often in fish from
the northern Pacific.
In the case of P. decipiens, eggs in seal feces are ingested by copepods, and L2- or early-L3-stage
larvae are ingested by the first intermediate host—fish. In fish, they penetrate the stomach wall, enter
the body cavity, and many burrow into fish muscles. In fish, the L3 larvae grow to 25–50 mm in length
and are red to brown in color. The final host, seals, tends to ingest the organisms principally from
smelt and other small fish.
Human infections occur upon the ingestion of fish that contain L3- and L4-stage larvae. Thus,
anisakids do not mature in humans. Disease symptoms arise from the activities of the juvenile worms.
A. simplex larvae are more harmful than those of P. decipiens because they often penetrate the mucosal
lining, whereas most P. decipiens larvae are passed in feces or are coughed up or vomited after irritating