97
Stress during capture has a significant impact on the animal’s muscle quality.
When different nucleotide profiles and other related metabolites were examined, it
was determined that the capture method had a significant effect on the energy state
of the abdominal muscles of Norwegian lobsters. In this study where the effect of
trawling and creel catching on the physiological state of the lobster was examined,
a better physiological state was observed in the lobster catching with creel. Creeled
lobsters managed to maintain muscle ATP levels; although a tendency for lower
arginine phosphate was detected when compared with rested undisturbed lobsters.
However, larger changes were observed in trawled animals. Norway lobsters, in
order to escape from the trawl, were immediately using anaerobic metabolism to
obtain energy, a situation that led rapidly to their exhaustion. It has been reported
that after 15 min in the trawl, the animals are already exhausted and no further
physiological changes are observed as the trawl time increases. Stress-related and
anaerobic metabolites together with muscle pH indicated that trawled animals, even
at the shortest time tested, were using anaerobic metabolism (Albalat et al. 2009).
To maintain the quality of lobsters, the following points should be considered
after catching. The deck where the lobsters are brought in should be kept clean.
Lobsters should be carefully removed from the pots as they may lose their claws and
legs due to stress. Any bleeding or damage to lobsters will reduce the chance of
survival during transport and storage. To prevent damage, lobsters should be carefully placed in tanks or boxes. Damaged lobsters should be returned to the sea
immediately. Lobsters should be placed in boxes covered with water-absorbing and
porous materials such as hemp sacks. These boxes should be stored in a place protected from wind and rain, not exposed to direct sunlight. Lobsters should never be
placed in a tank with still water. As the oxygen in the water will be exhausted rapidly and wastes will be formed in the water, it will have toxic effect. The lobsters
should be banded by hand to prevent claw losses. Recently moulted lobsters should
be kept separate until they harden. Otherwise they may be damaged (Irish Sea
Fisheries Board 2019).
Rapid microbial degradation during post-mortem storage such as in fish is an
important problem in the processing of cooked lobster. Components such as
non- protein nitrogenous compounds and free amino acids in crayfish are a source of
nutrients for microbial growth. As a result of microbial, enzymatic and oxidative
processes, lobster undergoes quality changes and loses its freshness. This significantly reduces its market value (Cremades et al. 2011). Micrococcus, Staphylococcus,
Alcaligenes and Achromobacter have been reported to be dominant strains in peeled
crayfish (Procanbarus clarkii) tails stored at 0 and 5 °C, and Pseudomonas and
Achromabacter have been described as spoilers (Cox and Lovell 1973).
Melanosis Formation in Lobsters
Melanosis, also known as blackspot, is an important cause of loss of lobster quality
during iced storage. Blackspot occurs in shellfish during storage as a result of the
action of polyphenoloxidase (PPO). PPO oxidizes diphenols to quinones, which
2.3 Lobsters
Stress during capture has a significant impact on the animal’s muscle quality.
When different nucleotide profiles and other related metabolites were examined, it
was determined that the capture method had a significant effect on the energy state
of the abdominal muscles of Norwegian lobsters. In this study where the effect of
trawling and creel catching on the physiological state of the lobster was examined,
a better physiological state was observed in the lobster catching with creel. Creeled
lobsters managed to maintain muscle ATP levels; although a tendency for lower
arginine phosphate was detected when compared with rested undisturbed lobsters.
However, larger changes were observed in trawled animals. Norway lobsters, in
order to escape from the trawl, were immediately using anaerobic metabolism to
obtain energy, a situation that led rapidly to their exhaustion. It has been reported
that after 15 min in the trawl, the animals are already exhausted and no further
physiological changes are observed as the trawl time increases. Stress-related and
anaerobic metabolites together with muscle pH indicated that trawled animals, even
at the shortest time tested, were using anaerobic metabolism (Albalat et al. 2009).
To maintain the quality of lobsters, the following points should be considered
after catching. The deck where the lobsters are brought in should be kept clean.
Lobsters should be carefully removed from the pots as they may lose their claws and
legs due to stress. Any bleeding or damage to lobsters will reduce the chance of
survival during transport and storage. To prevent damage, lobsters should be carefully placed in tanks or boxes. Damaged lobsters should be returned to the sea
immediately. Lobsters should be placed in boxes covered with water-absorbing and
porous materials such as hemp sacks. These boxes should be stored in a place protected from wind and rain, not exposed to direct sunlight. Lobsters should never be
placed in a tank with still water. As the oxygen in the water will be exhausted rapidly and wastes will be formed in the water, it will have toxic effect. The lobsters
should be banded by hand to prevent claw losses. Recently moulted lobsters should
be kept separate until they harden. Otherwise they may be damaged (Irish Sea
Fisheries Board 2019).
Rapid microbial degradation during post-mortem storage such as in fish is an
important problem in the processing of cooked lobster. Components such as
non- protein nitrogenous compounds and free amino acids in crayfish are a source of
nutrients for microbial growth. As a result of microbial, enzymatic and oxidative
processes, lobster undergoes quality changes and loses its freshness. This significantly reduces its market value (Cremades et al. 2011). Micrococcus, Staphylococcus,
Alcaligenes and Achromobacter have been reported to be dominant strains in peeled
crayfish (Procanbarus clarkii) tails stored at 0 and 5 °C, and Pseudomonas and
Achromabacter have been described as spoilers (Cox and Lovell 1973).
Melanosis Formation in Lobsters
Melanosis, also known as blackspot, is an important cause of loss of lobster quality
during iced storage. Blackspot occurs in shellfish during storage as a result of the
action of polyphenoloxidase (PPO). PPO oxidizes diphenols to quinones, which
2.3 Lobsters