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Wild and farmed lobsters (Homarus gammarus). A comparison of yield, proximate chemical composition and sensory properties
A~uaeuZture, 29 (1982) 147-154 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
147
WILD AND FARMED LOBSTERS (HOMARUS GAMMARUS). A COMPARISON OF YIELD, PROXIMATE CHEMICAL COMPOSITION AND SENSORY PROPERTIES
GEOFFREY
D. STROUD and ERIC J. DALGARNO
~inist~ ofAgriculture, Fisheries and Food, Tarry Research 135 Abbey Road, Aberdeen (Great Britain) (Accepted
Station,
P.0. BOX 31,
13 November 1981)
ABSTRACT Stroud, G.D. and Dalgarno, E.J., 1982. Wild and farmed lobsters (Homarus gammarus). A comparison of yield, proximate chemical composition and sensory properties. A~uacu~t~re, 29: 147-154. Farmed lobsters (Homarus gammarus) from the Fisheries Experiment Station at Conwy and wild lobsters from Anglesey were compared with regard to yield, proximate chemical composition and sensory properties. Odour, flavour, texture and proximate composition were found to be very similar, but the appearance of the whole cooked wild lobsters was preferred to that of the farmed samples.
INTRODUCTION
Experimental work on the artificial rearing of lobsters (~0~~~~s g~~~~r~s) has been in progress in Great Britain since 1973 at the Ministry of Agriculture, Fisheries and Food Fisheries Experiment Station, Conwy, and a pilot plant culture system was set up in 1977 to study the production and rearing of lobsters to marketable size. This work was sponsored by the Fishmongers’ Company of the United Kingdom and the results of this work have recently been published (Richards and Wickins, 1979; Wickins and Richards, 1980; Richards et al., 1982). Six of the first specimens to reach marketable size were assessed by Torry Research Station at the request of the Conwy Laboratory for yield of edible meat, organoleptic acceptability and proximate composition. The results obtained were compared with those obtained from six wild lobsters of the same species from Anglesey. No work appears to have been carried out so far on differences between farmed and wild lobsters and the literature on differences in chemical composition and sensory acceptability between farmed and wild fish is limited. Such studies that are available indicate that differences do occur, particularly in the acceptability of some products, but the differences are not consistent.
0044-8486182/0000-0000~$02.75
Q 1982 Elsevier Scientific Publishing Company
148
Studies on cage-cultured and wild scallops showed that the proximate composition of both groups was similar, and that variability within the groups was not significantly different (Naidu and Botta, 1978). Investigations to determine compositional differences between wild and cultured yellowtail showed that there were larger variations in protein, lipid, moisture and ash between parts of the same fish than between individu~s (Saeki and Kumagai, 1979). Differences in the flavour and sensory acceptability of farmed and wild fish and shellfish have been reported previously. Cultured shrimp were found to have a flavour equal to or better than that of pop~ations of wild shrimp (~dmunds and Lillard, 1979). The United Kingdom White Fish Autho~ty’s trials of farmed turbot, plaice and sole showed that the majority of consumers could not distinguish between the farmed and wild fish and that the farmed fish were equally as acceptable as the wild caught samples (Anonymous, 1970; 1974). No significant differences were found in cooked odour, texture and flavour between farmed and wild scallops (Naidu and Botta, 1978), but farmed plaice were reported to have a dist~ctive and unnatur~ flavour when compared with the wild fish (Hume et al., 1972).
The farmed lobsters were weighed i~di~du~ly before despatch and sent alive by rail to Torry Research Station. Six wild lobsters, caught off Anglesey, were also despatched by rail at the same time. The lobsters were unpacked, inspected and then placed in a boiling 3% salt solution and boiled for 20 min. The wild lobsters were weighed before boiling. During boiling, the farmed and wild lobsters were contained in separate muslin bags. After boiling, the lobsters were cooled by washing with cold water and then stored in a chillroom overnight. The following morning the lobsters were weighed and examined by a panel of six judges for cooked appearance, before the samples were butchered into the component parts of claws, tails and “body”, In this eontext the term “body” includes the cephalothorax and legs. Each part was weighed, the white meat was extracted from the claws and tail and the brown meat from the body. The meats were then weighed and examined by the panel for appearance, cooked odour, texture and flavour. Analyses for total nitrogen (TN), non-protein nitrogen (NPN), ash, fat, moisture and glycogen were carried out on minced samples of the meats. There was insufficient material to carry out a full analysis on the brown meat from the bodies of both the wild and farmed samples. Total nitrogen (TN) was determined in duplicate by solubilizing an accurately weighed portion (- 1 g) of the minced sample in 30 ml of 60% sulphuric acid for 2 h at 60°C. After cooling and diluting to 100 ml, a 5-ml sample was digested in a micro Kjeldahl flask, with 0.6 ml of concentrated sulphuric acid and 1.5 g of potassium sulphate/mercury catalyst, for 30 min after the solution had cleared. After cooling, the digest was transferred quantitatively
149
to a Hoskins distillation apparatus, 10 ml of 40% sodium hydroxide solution containing 2.0% sodium thiosulphate was added and the mixture was distilled for a total of 12 min. The distillate was collected in 5 ml of 2% boric acid containing BDH 4-5 screened indicator and titrated with 0.01 N hydrochloric acid. Non-protein nitrogen (NPN) determinations were carried out in duplicate by extracting a.n accurately weighed sample (- 0.8 g) with 80 ml of 10% t~chloroacetic acid in an MSE homogeniser for 1 min. The homogenate was filtered, 10 ml of the filtrate taken and digested in a microKjeldahl flask, with 1.5 ml concentrated sulphuric acid and 1.5 g potassium sulphate/mercury catalyst, for 30 min after the solution had cleared. The total digest was cooled and made up to 50 ml with distilled water; a 15-ml sample was steam distilled in a Hoskins still and the nitrogen content determined as reported above. Protein values were calculated according to the following formula (TN - NPN) X 6.25. Ash contents were determined in triplicate by ashing at 500°C for 24 h, with 1 ml of 5% magnesium acetate as an ashing aid. Fat contents were measured in duplicate by the method of Bligh and Dyer (1959), modified by Hanson and Olley (1963). There was insufficient material to carry out fat determinations on samples of claw and tail meat from each individual fish and so analyses were carried out in duplicate on a bulked sample of each kind of meat. Moisture contents of each type of meat were determined by drying three samples of the mince at 106°C for 24 h. Glycogen was estimated by the method of Roe and Dailey (1966). One of the farmed lobsters had a claw missing; complete analysis of this sample was not possible because of insufficient material. RESULTS
AND DISCUSSION
Chemical composition In all cases in the present investigation, the chemical composition (Table I) was less variable in the farmed samples than in the wild stock, the controlled en~ronment in which the farmed animals are reared probably being responsible for this finding. Significant differences between the farmed and wild samples, at least the 5% significance level, were found for NPN, protein and moisture in the claw meat, and for NPN and glycogen in the tail meat. Cultivation did not increase the energy reserves in the muscle tissue, the glycogen levels in the tail meat of the wild stock in fact being higher than those found in the cultivated lobsters, perhaps a sign of a more active life of the wild animal. Although consistent differences in chemical composition of the claw and tail meats were observed between the two groups, the differences were not consistent in direction, as is demonstrated in Table I. As the moisture level of lobster flesh is altered by cooking in boiling salted water, the moisture contents reported do not necessarily reflect those in the raw flesh.
74.72 75.68 - 0.96 N.S.
67.48 67.12 + 0.36 N.S.
Tail meat Farmed Wild Difference (F-W)
Body meat Farmed Wild Difference (F-W)
0.80 1.12
0.47 1.56 1.90
1.73 1.50 +0.23 N.S.
1.82 1.94 -0.12 N.S.
-
0.06 0.15
0.20 -
3.81 3.81 0.00 N.S.
3.43 3.21 +0.22 N.S. 0.14 0.21
0.16 0.32
SD. __--
1.12 1.01 -J-O.11 *
0.86 1.01 -0.15 *
Mean
%NPN
0.07 0.10
0.05 0.10
16.79 17.50 - 0.71 N.S.
16.08 13.79 + 2.29 *
S.D. Mean -----
% Protein --
N.B. When determined, the significance of a difference is indicated as follows: * ** = significant at 5%, 1% level respectively; N.S. = not significant at the 5% level. F’= Farmed; W = Wild.
75.84 77.78 - 1.94 *
Claw meat Farmed Wild Difference (F-W)
Mean
SD. ----
Mean
Mean --___-
S.D.
%TN
% Ash
% Moisture pw
Chemical analysis of farmed and wild lobsters
TABLE I
0.79 1.17
0.81 2.17
SD. ~--~-
0.45 0.82 -0.37 **
0.97 1.05 -0.08 N.S.
Mean
0.16 0.19
0.20 0.25
S.D.
% Glyeogen ~--1--
1.28 1.22 +0.06
1.16 1.10 +0.06
Mean
% Fat ___
151
Yield of meat Significantly higher percentage yields of white meat from both claws and tails were obtained from the farmed lobsters (Tables II and III). Percentage yields of brown meat from the body were not significantly different, but as the brown meat is not normally used, this result is of less commercial importance. As the weights of the farmed lobsters, however, were significantly higher than those of the wild samples (mean boiled weight 373 g compared with 269 g) and the distribution of the sexes was different, there is insufficient data to say whether the differences in yields are due to farming or to the differences in size and sex. It was not possible to carry out tests of significance on the weight loss of the wild lobsters as these samples were not tagged and individual weight losses were not obtained. TABLE II Yields of meat from farmed and wild lobsters, expressed as a percentage of the whole cooked animal Claw meat
Farmed a Wild Difference (F-W)
Tail meat ___-
Body meat
Mean
S.D.
Mean
S.D.
Mean
S.D.
14.22 12.27 + 1.95 *
0.61 2.06
21.34 17.62 + 3.72 **
1.92 0.86
2.24 2.00 0.24 N.S.
0.93 0.82
a Omitting lobster with one claw. TABLE III Yields of meat from farmed and wild lobsters, expressed as a percentage of the meatcontaining component Claw meat
-
Tail meat ~~
Body meat
Mean
S.D.
Mean
S.D.
Mean
S.D.
50.38 40.59 + 9.79 *
2.83 5.99
72.47 65.25 + 7.22 *
2.77 5.00
5.00 5.43 -0.43 N.S.
2.37 2.24
~
Farmed Wild Difference (F-W)
F = Farmed; W = Wild. *, ** = significant at 5% and 1% level respectively; N.S. not significant at the 5% level.
152 TABLE
IV
Mean live weight,
boiled
weights
and percentage
loss of weight
on boiling
_~ Live weight
Farmed a Wild Difference (F-W) ___
(g)
Boiled weight ~-
(g)
% Loss on boiling
Mean
S.D.
Mean
S.D.
S.D.
391 320 f 71 ** _^ _~
24 32
373 269 t104 ***
23 33
4.6 15.9 -11.3
_..._
-
~_._.
**, *** significant at the 1% and 0.1% levels respectively. a Omitting the lobster with one claw.
Taste panel assessment of whole lobsters The shells of the whole cooked wild lobsters were a uniform bright crimson red colour on the dorsal surface with a mottled creamy red ventral surface (Table V). This table was compiled by combining the comments of individu~ panel members and selecting the descriptors most frequently used, The shells of the farmed lobsters had a rusty mottled appearance with a pale orange colour, which in some cases was covered by a thin layer of algal growth, masking the actual colour. The algal growth was easily removed by washing and scrubbing, There was, however, a marked preference for the wild lobster over the farmed samples, in terms of appearance.
Taste panel assessment of the cooked meats In general, little difference in the cooked odour and flavour of the claw and tail meat was found between the farmed and wild samples (see Table V). All had sweet characteristic shellfishy flavours with slight acrid overtones, Similarly, the odours were described as being slight shellfishy and seaweedy to bland and neutral. The texture of the claw and tail meats from both farmed and wild samples was described as firm and chewy, and in some cases tough. The tail meat from the wild lobsters tended to be tougher and drier than the other samples. There was a marked difference in appearance between the farmed and wild samples of both the claw and tail meats. The hypodermis of the wild samples was dark red, p~ti~ul~ly that of the tail meat, while that of the farmed samples was pale orange. The colour of the flesh from both sets of tails and claws was white with a slight pink tinge. The claw meat was whiter than the tail meat, the farmed claws being slightly darker and less translucent than the wild controls. The paler colour of the hypodermis of the farmed lobsters did not detract from their acceptability, and in some cases was preferred to the dark red colour of the wild samples.
153 TABLE
V
Sensory
assessment
of wild and farmed
Odour
lobsters Flavour
Whole cooked (wild)
Bright
Whole cooked (fanned)
Rusty, mottled, pale x-an@?. green algal growth
Tail meat (wild)
meat
Neutral, shellfish, milky, sweet, seaweed
Sweet.shellfish. meaty,
milky slight acrid
Dark red hypodermis with white/pinkish flesh Orange/pink white/pinkish
Metallic, characteristic sweetness. slight acrid, slight burnt
Firm,
chewy,
Claw (wild)
Slight shellfish. bland, slightly salty, slightly seaweedy
Slight sweetness, sweet. shellfish. slight acrid, slightly salty, slightly metallic
Finn. slight
fibrous, softness
chewy,
Claw meat (farmed)
Slight shellfish, marine, seaweedy
Sweet, shellfish, slight saltiness. slightly tumipy, slightly meaty, metallic. slight acrid
Finn. moist
chewy,
fibrous,
Brown meat (wild)
oily, faint
_
(farmed)
meat
Brown meat (fanned)
meaty, odour,
Oily, bland, II-l&y
very bland slightly
Soft,
tough
soft.
hypodermis flesh
Mottled red/pink hypodermis, white/slightly translucent flesh Pale orange/pink hypodermis. creamy white flesh
pasty.
slightly
Brown, greyish
pasty.
SlOPPY
Greyish, khaki, light brown, pale yellow
lumpy
-
crimson
Firm. chewy. dry, tough, fibrous
Neutral, earthy. slight shellfish. mxssy. bland, slightly seaweedy
Tail
red.
pale brown/ bluey/grey
CONCLUSIONS
The results of these trials indicate that there are no major differences in eating quality, yield of meat, and chemical composition between the farmed and wild samples. The proximate chemical composition of the wild stock was more variable than the farmed samples. This might be accounted for by the more controlled environment and feeding regime of the farmed lobsters. Differences in the colour of the shells of the whole boiled animals made the farmed samples less acceptable than the wild lobster, the panel preferring the bright red colour of the wild sample. This discrimination against the appearance of the farmed lobster was not apparent after shelling. Some consumer resistance therefore may be encountered on account of the appear ante of the whole cooked farmed lobster, reared under the conditions of the Conwy trial, but in terms of yield, flavour and appearance of the shelled meat, the farmed samples are very similar to the wild ones.
REFERENCES Anonymous, 1970. Preference test on wild and farmed fish. Trials Rec. No. 49, White Fish Authority, Industrial Development Unit, Hull, pp. l-33.
154 Anonymous, 1974. Consumer acceptability of farmed turbot. Tech. Rep. No. 113, White Fish Authority, Market Development Unit, Epsom, Surrey, pp. l-22. Bligh, E.G. and Dyer, W.J., 1959. A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol., 37: 911-917. Edmunds, W.J. and Lillard, D.A., 1979. Sensory characteristics of oysters, clams and cultivated and wild shrimp. J. Food Sci., 44(2): 368-373. Hanson, S.W.F. and Olley, J., 1963. Application of Bligh and Dyer method of lipid extraction to tissue homogenates. Biochem. J., 89: 101-102. Hume, A., Farmer, J.W. and Burt, J.R., 1972. A comparison of flavours of farmed and trawled plaice. J. Food Technol., 7(l): 27-33. Naidu, K.S. and Botta, J.R., 1978. Taste panel assessment and proximate composition of cultured and wild sea scallops, Placopecten magellanicus. Aquaculture, 15(3): 243-247 Richards, P.R. and Wickins, J.F., 1979. Lobster culture research. Lab Leafl., MAFF Direct. Fish. Res., Lowestoft (47), pp. l-33. Richards, P.R., Beard, T.W. and Wickins, J.F., 1982. A laboratory scale pilot plant for the continuous production of lobsters. In preparation. Roe, J.H. and Dailey, R.E., 1966. Determination of glycogen with the anthrone reagent. Analyt. Biochem., 15: 245-250. Saeki, K. and Kamagai, H., 1979. Muscle components of wild and cultured yellowtail. J. Food Hyg. Sot. J., 20(2): 101-105. Wickins, J.F. and Richards, P.R., 1980. Prawn culture and lobster culture. In: Proc. Shellfish Association of Great Britain. The Dr Walne Memorial Lecture, 13 May 1980. Published by Janssen Services, London, pp. 3-23.
147
WILD AND FARMED LOBSTERS (HOMARUS GAMMARUS). A COMPARISON OF YIELD, PROXIMATE CHEMICAL COMPOSITION AND SENSORY PROPERTIES
GEOFFREY
D. STROUD and ERIC J. DALGARNO
~inist~ ofAgriculture, Fisheries and Food, Tarry Research 135 Abbey Road, Aberdeen (Great Britain) (Accepted
Station,
P.0. BOX 31,
13 November 1981)
ABSTRACT Stroud, G.D. and Dalgarno, E.J., 1982. Wild and farmed lobsters (Homarus gammarus). A comparison of yield, proximate chemical composition and sensory properties. A~uacu~t~re, 29: 147-154. Farmed lobsters (Homarus gammarus) from the Fisheries Experiment Station at Conwy and wild lobsters from Anglesey were compared with regard to yield, proximate chemical composition and sensory properties. Odour, flavour, texture and proximate composition were found to be very similar, but the appearance of the whole cooked wild lobsters was preferred to that of the farmed samples.
INTRODUCTION
Experimental work on the artificial rearing of lobsters (~0~~~~s g~~~~r~s) has been in progress in Great Britain since 1973 at the Ministry of Agriculture, Fisheries and Food Fisheries Experiment Station, Conwy, and a pilot plant culture system was set up in 1977 to study the production and rearing of lobsters to marketable size. This work was sponsored by the Fishmongers’ Company of the United Kingdom and the results of this work have recently been published (Richards and Wickins, 1979; Wickins and Richards, 1980; Richards et al., 1982). Six of the first specimens to reach marketable size were assessed by Torry Research Station at the request of the Conwy Laboratory for yield of edible meat, organoleptic acceptability and proximate composition. The results obtained were compared with those obtained from six wild lobsters of the same species from Anglesey. No work appears to have been carried out so far on differences between farmed and wild lobsters and the literature on differences in chemical composition and sensory acceptability between farmed and wild fish is limited. Such studies that are available indicate that differences do occur, particularly in the acceptability of some products, but the differences are not consistent.
0044-8486182/0000-0000~$02.75
Q 1982 Elsevier Scientific Publishing Company
148
Studies on cage-cultured and wild scallops showed that the proximate composition of both groups was similar, and that variability within the groups was not significantly different (Naidu and Botta, 1978). Investigations to determine compositional differences between wild and cultured yellowtail showed that there were larger variations in protein, lipid, moisture and ash between parts of the same fish than between individu~s (Saeki and Kumagai, 1979). Differences in the flavour and sensory acceptability of farmed and wild fish and shellfish have been reported previously. Cultured shrimp were found to have a flavour equal to or better than that of pop~ations of wild shrimp (~dmunds and Lillard, 1979). The United Kingdom White Fish Autho~ty’s trials of farmed turbot, plaice and sole showed that the majority of consumers could not distinguish between the farmed and wild fish and that the farmed fish were equally as acceptable as the wild caught samples (Anonymous, 1970; 1974). No significant differences were found in cooked odour, texture and flavour between farmed and wild scallops (Naidu and Botta, 1978), but farmed plaice were reported to have a dist~ctive and unnatur~ flavour when compared with the wild fish (Hume et al., 1972).
The farmed lobsters were weighed i~di~du~ly before despatch and sent alive by rail to Torry Research Station. Six wild lobsters, caught off Anglesey, were also despatched by rail at the same time. The lobsters were unpacked, inspected and then placed in a boiling 3% salt solution and boiled for 20 min. The wild lobsters were weighed before boiling. During boiling, the farmed and wild lobsters were contained in separate muslin bags. After boiling, the lobsters were cooled by washing with cold water and then stored in a chillroom overnight. The following morning the lobsters were weighed and examined by a panel of six judges for cooked appearance, before the samples were butchered into the component parts of claws, tails and “body”, In this eontext the term “body” includes the cephalothorax and legs. Each part was weighed, the white meat was extracted from the claws and tail and the brown meat from the body. The meats were then weighed and examined by the panel for appearance, cooked odour, texture and flavour. Analyses for total nitrogen (TN), non-protein nitrogen (NPN), ash, fat, moisture and glycogen were carried out on minced samples of the meats. There was insufficient material to carry out a full analysis on the brown meat from the bodies of both the wild and farmed samples. Total nitrogen (TN) was determined in duplicate by solubilizing an accurately weighed portion (- 1 g) of the minced sample in 30 ml of 60% sulphuric acid for 2 h at 60°C. After cooling and diluting to 100 ml, a 5-ml sample was digested in a micro Kjeldahl flask, with 0.6 ml of concentrated sulphuric acid and 1.5 g of potassium sulphate/mercury catalyst, for 30 min after the solution had cleared. After cooling, the digest was transferred quantitatively
149
to a Hoskins distillation apparatus, 10 ml of 40% sodium hydroxide solution containing 2.0% sodium thiosulphate was added and the mixture was distilled for a total of 12 min. The distillate was collected in 5 ml of 2% boric acid containing BDH 4-5 screened indicator and titrated with 0.01 N hydrochloric acid. Non-protein nitrogen (NPN) determinations were carried out in duplicate by extracting a.n accurately weighed sample (- 0.8 g) with 80 ml of 10% t~chloroacetic acid in an MSE homogeniser for 1 min. The homogenate was filtered, 10 ml of the filtrate taken and digested in a microKjeldahl flask, with 1.5 ml concentrated sulphuric acid and 1.5 g potassium sulphate/mercury catalyst, for 30 min after the solution had cleared. The total digest was cooled and made up to 50 ml with distilled water; a 15-ml sample was steam distilled in a Hoskins still and the nitrogen content determined as reported above. Protein values were calculated according to the following formula (TN - NPN) X 6.25. Ash contents were determined in triplicate by ashing at 500°C for 24 h, with 1 ml of 5% magnesium acetate as an ashing aid. Fat contents were measured in duplicate by the method of Bligh and Dyer (1959), modified by Hanson and Olley (1963). There was insufficient material to carry out fat determinations on samples of claw and tail meat from each individual fish and so analyses were carried out in duplicate on a bulked sample of each kind of meat. Moisture contents of each type of meat were determined by drying three samples of the mince at 106°C for 24 h. Glycogen was estimated by the method of Roe and Dailey (1966). One of the farmed lobsters had a claw missing; complete analysis of this sample was not possible because of insufficient material. RESULTS
AND DISCUSSION
Chemical composition In all cases in the present investigation, the chemical composition (Table I) was less variable in the farmed samples than in the wild stock, the controlled en~ronment in which the farmed animals are reared probably being responsible for this finding. Significant differences between the farmed and wild samples, at least the 5% significance level, were found for NPN, protein and moisture in the claw meat, and for NPN and glycogen in the tail meat. Cultivation did not increase the energy reserves in the muscle tissue, the glycogen levels in the tail meat of the wild stock in fact being higher than those found in the cultivated lobsters, perhaps a sign of a more active life of the wild animal. Although consistent differences in chemical composition of the claw and tail meats were observed between the two groups, the differences were not consistent in direction, as is demonstrated in Table I. As the moisture level of lobster flesh is altered by cooking in boiling salted water, the moisture contents reported do not necessarily reflect those in the raw flesh.
74.72 75.68 - 0.96 N.S.
67.48 67.12 + 0.36 N.S.
Tail meat Farmed Wild Difference (F-W)
Body meat Farmed Wild Difference (F-W)
0.80 1.12
0.47 1.56 1.90
1.73 1.50 +0.23 N.S.
1.82 1.94 -0.12 N.S.
-
0.06 0.15
0.20 -
3.81 3.81 0.00 N.S.
3.43 3.21 +0.22 N.S. 0.14 0.21
0.16 0.32
SD. __--
1.12 1.01 -J-O.11 *
0.86 1.01 -0.15 *
Mean
%NPN
0.07 0.10
0.05 0.10
16.79 17.50 - 0.71 N.S.
16.08 13.79 + 2.29 *
S.D. Mean -----
% Protein --
N.B. When determined, the significance of a difference is indicated as follows: * ** = significant at 5%, 1% level respectively; N.S. = not significant at the 5% level. F’= Farmed; W = Wild.
75.84 77.78 - 1.94 *
Claw meat Farmed Wild Difference (F-W)
Mean
SD. ----
Mean
Mean --___-
S.D.
%TN
% Ash
% Moisture pw
Chemical analysis of farmed and wild lobsters
TABLE I
0.79 1.17
0.81 2.17
SD. ~--~-
0.45 0.82 -0.37 **
0.97 1.05 -0.08 N.S.
Mean
0.16 0.19
0.20 0.25
S.D.
% Glyeogen ~--1--
1.28 1.22 +0.06
1.16 1.10 +0.06
Mean
% Fat ___
151
Yield of meat Significantly higher percentage yields of white meat from both claws and tails were obtained from the farmed lobsters (Tables II and III). Percentage yields of brown meat from the body were not significantly different, but as the brown meat is not normally used, this result is of less commercial importance. As the weights of the farmed lobsters, however, were significantly higher than those of the wild samples (mean boiled weight 373 g compared with 269 g) and the distribution of the sexes was different, there is insufficient data to say whether the differences in yields are due to farming or to the differences in size and sex. It was not possible to carry out tests of significance on the weight loss of the wild lobsters as these samples were not tagged and individual weight losses were not obtained. TABLE II Yields of meat from farmed and wild lobsters, expressed as a percentage of the whole cooked animal Claw meat
Farmed a Wild Difference (F-W)
Tail meat ___-
Body meat
Mean
S.D.
Mean
S.D.
Mean
S.D.
14.22 12.27 + 1.95 *
0.61 2.06
21.34 17.62 + 3.72 **
1.92 0.86
2.24 2.00 0.24 N.S.
0.93 0.82
a Omitting lobster with one claw. TABLE III Yields of meat from farmed and wild lobsters, expressed as a percentage of the meatcontaining component Claw meat
-
Tail meat ~~
Body meat
Mean
S.D.
Mean
S.D.
Mean
S.D.
50.38 40.59 + 9.79 *
2.83 5.99
72.47 65.25 + 7.22 *
2.77 5.00
5.00 5.43 -0.43 N.S.
2.37 2.24
~
Farmed Wild Difference (F-W)
F = Farmed; W = Wild. *, ** = significant at 5% and 1% level respectively; N.S. not significant at the 5% level.
152 TABLE
IV
Mean live weight,
boiled
weights
and percentage
loss of weight
on boiling
_~ Live weight
Farmed a Wild Difference (F-W) ___
(g)
Boiled weight ~-
(g)
% Loss on boiling
Mean
S.D.
Mean
S.D.
S.D.
391 320 f 71 ** _^ _~
24 32
373 269 t104 ***
23 33
4.6 15.9 -11.3
_..._
-
~_._.
**, *** significant at the 1% and 0.1% levels respectively. a Omitting the lobster with one claw.
Taste panel assessment of whole lobsters The shells of the whole cooked wild lobsters were a uniform bright crimson red colour on the dorsal surface with a mottled creamy red ventral surface (Table V). This table was compiled by combining the comments of individu~ panel members and selecting the descriptors most frequently used, The shells of the farmed lobsters had a rusty mottled appearance with a pale orange colour, which in some cases was covered by a thin layer of algal growth, masking the actual colour. The algal growth was easily removed by washing and scrubbing, There was, however, a marked preference for the wild lobster over the farmed samples, in terms of appearance.
Taste panel assessment of the cooked meats In general, little difference in the cooked odour and flavour of the claw and tail meat was found between the farmed and wild samples (see Table V). All had sweet characteristic shellfishy flavours with slight acrid overtones, Similarly, the odours were described as being slight shellfishy and seaweedy to bland and neutral. The texture of the claw and tail meats from both farmed and wild samples was described as firm and chewy, and in some cases tough. The tail meat from the wild lobsters tended to be tougher and drier than the other samples. There was a marked difference in appearance between the farmed and wild samples of both the claw and tail meats. The hypodermis of the wild samples was dark red, p~ti~ul~ly that of the tail meat, while that of the farmed samples was pale orange. The colour of the flesh from both sets of tails and claws was white with a slight pink tinge. The claw meat was whiter than the tail meat, the farmed claws being slightly darker and less translucent than the wild controls. The paler colour of the hypodermis of the farmed lobsters did not detract from their acceptability, and in some cases was preferred to the dark red colour of the wild samples.
153 TABLE
V
Sensory
assessment
of wild and farmed
Odour
lobsters Flavour
Whole cooked (wild)
Bright
Whole cooked (fanned)
Rusty, mottled, pale x-an@?. green algal growth
Tail meat (wild)
meat
Neutral, shellfish, milky, sweet, seaweed
Sweet.shellfish. meaty,
milky slight acrid
Dark red hypodermis with white/pinkish flesh Orange/pink white/pinkish
Metallic, characteristic sweetness. slight acrid, slight burnt
Firm,
chewy,
Claw (wild)
Slight shellfish. bland, slightly salty, slightly seaweedy
Slight sweetness, sweet. shellfish. slight acrid, slightly salty, slightly metallic
Finn. slight
fibrous, softness
chewy,
Claw meat (farmed)
Slight shellfish, marine, seaweedy
Sweet, shellfish, slight saltiness. slightly tumipy, slightly meaty, metallic. slight acrid
Finn. moist
chewy,
fibrous,
Brown meat (wild)
oily, faint
_
(farmed)
meat
Brown meat (fanned)
meaty, odour,
Oily, bland, II-l&y
very bland slightly
Soft,
tough
soft.
hypodermis flesh
Mottled red/pink hypodermis, white/slightly translucent flesh Pale orange/pink hypodermis. creamy white flesh
pasty.
slightly
Brown, greyish
pasty.
SlOPPY
Greyish, khaki, light brown, pale yellow
lumpy
-
crimson
Firm. chewy. dry, tough, fibrous
Neutral, earthy. slight shellfish. mxssy. bland, slightly seaweedy
Tail
red.
pale brown/ bluey/grey
CONCLUSIONS
The results of these trials indicate that there are no major differences in eating quality, yield of meat, and chemical composition between the farmed and wild samples. The proximate chemical composition of the wild stock was more variable than the farmed samples. This might be accounted for by the more controlled environment and feeding regime of the farmed lobsters. Differences in the colour of the shells of the whole boiled animals made the farmed samples less acceptable than the wild lobster, the panel preferring the bright red colour of the wild sample. This discrimination against the appearance of the farmed lobster was not apparent after shelling. Some consumer resistance therefore may be encountered on account of the appear ante of the whole cooked farmed lobster, reared under the conditions of the Conwy trial, but in terms of yield, flavour and appearance of the shelled meat, the farmed samples are very similar to the wild ones.
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