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Storage properties of blue whiting after mincing by different methods
Storage properties of blue whiting after mincing by different methods A . J. B o r d e r i a s , A . M o r a l a n d E. G a r c i a M a t a m o r o s
Propri6t6s du merlan bleu cours de la conservation, apr s mise en hachis par diff6rentes m6thodes
au
Pour obtenir /ndustriellement des hach/s de poisson de diff#rentes esp#ces, /I est n#cessaire de connaTtre /e comportement ~ /'#tat congel# du bach/s, obtenu par dfff#rentes re#rhodes. Le hach/s de po/sson pr#par# ~ partir d'appareils ~ couteaux sera admissible pour les esp#ces qui peuvent #tre filet#es industriellement, ce qu/ permet d'ajouter de/'eau refroidie et des additifs au cours de/a pr#parat/on du
bach/s, en vue d'obten/r une texture fine. La pr#parat/on du hachis par broyage conv/ent aussi ~ ce genre d'esp#ces. L "extrusion peut #tre util/s#e pour un grand nombre d'esp#ces de po/ssons et peut #tre employ#e avec route m#thode de preparation du poisson. Au cours de la p#riode de conservation, jusqu'au lOe mois, /a diminution des prot#/nes so/ub/es est p/us fa/ble pour/e hachis de poisson obtenu avec des appareils ~ couteaux que pour/e hachis r#sultant du broyage ou de/'extrusion. Les #valuat/ons de jurys de d#gustation montrent que tous /es lots sont acceptables jusqu'au 7e mois de conservation; aude/& /e lot obtenu par/es apparei/s ~ couteaux devient /nacceptable, a/ors que /es r#sultats des deux autres lots sont loin de mainten/r /a qua//M opt/male.
The industrial objective of obtaining minced fish of different types necessitates investigating the frozen storage behaviour of minced fish obtained by different methods. The minced fish prepared by using the 'cutter method" would be advisable for those fish species that can be filleted industrially; this allows the addition of chilled water and many additives during the preparation of minced fish, resulting in a fine texture. The 'mincing method" is also appropriate for such species. Extrusion is applicable to a great number of types of fish, and can be used with any method of preparation of fish.
During the storage period, the decrease of soluble proteins appears to be less in minced fish obtained by the 'mincing method' than in minces obtained by the 'cutter' and 'extrusion' methods, upto the tenth month of storage. The taste panel evaluations show that all the lots were acceptable until the seventh month of storage, but from that time onwards the lot minced by the 'cutter' was not acceptable and the scores for the other two lots were far from optimal.
Introduction
fine structure; 2 - the mincing method; and 3 - the extrusion method. The latter gives larger particles than the preceeding methods, the size of which can be controlled by using different orifices.
Frozen minced fish is an industrially interesting product, but more information is needed on the storage behaviour of minced fish of different species, and the quality obtained by different methods. The method of mincing will affect the physical structure which determines both the organoleptic properties of the product and its behaviour towards freezing and subsequent storage. The purpose of the experimental study described here was to compare the advantages and disadvantages of each of the following methods of obtaining minces: 1 - the 'cutter' method (simultaneous cutting and homogenisation) which gives fish minces with a very The authors are at the Instituto del Frio, Ciudad Universitaria, Madrid - 3, Spain. This paper was first presented at the 5th International Congress of Food Science and Technology, Kyoto, Japan
42
0140-7007/80/010042-05 $02.00 © 1980 IPC Business Press Ltd. and IIR
As blue whiting (Micromesistius poutassou, Risso) is both abundant and commercially undervalued in Spain, we decided to use it in our experiments with a view to revaluating it.
Materials and methods Production and dressing of samples The blue whiting samples used in the experiments had been caught by the oceanographic ship 'Corn/de de Saavedra' on the Galician coastal shelf. After being sorted, the fishes were beheaded, gutted, thoroughly washed, and then divided into three lots as follows. Lot PT Samples were prepared by cutting fillets of fish in a conventional mincing machine with plate orifices of 5 mm; 12 kg of minced fish were sampled
International Journal of Refrigeration
into a number of trays containing about 0.5 kg each, for immediate freezing at -35 ° to -40°C in a multiplate 'Jackstone' freezer with a capacity of 524 kg per 24 h. All operations were carried out on the ship's deck at ambient temperature (14 ° to 16°C). The minced frozen fish was vacuum-packed in polyethylene bags with an 'Euvac 70/40' machine, and subsequently stored on board in a freezer room at -20°C. Lot BT Treated as for lot PT, except that the fish was not filleted and the mince was obtained by extrusion in a 'Baader Model 694' extruder. Lot CT The fish, after being prepared as indicated above, was frozen under the same conditions as the minces; they were subsequently taken to the Instituto del Frio (IF), where they were slowly thawed for 72 h at 0 ° to 2°C in a forced air circulation chamber. This fish, at a temperature between 0 ° and -2°C, was filleted in a room at 5°C. The fillets were minced in a Vivar HP 2.50/375 cutter, the process of simultaneous cutting and homogenisation being completed in 10 min at maximum speed; it was necessary to add 23% of water at 0°C to the product so as to avoid temperature rises and, consequent prot.ein denaturation. The freezing, packing and storage of samples was done as in the preceding lots. The samples were taken from the ship's cold chambers to the IF pilot plant at -20°C in a refrigerated lorry equipped with a compressor unit. All samples were stored at the same temperature (-20°C) for 12 months.
Every 1-2 months, samples were sawn into 1 to 1.5 cm blocks; these were used for quality control tests. These tests included measurements of: pH - determined on a macerated mince/distilled water mix in the ratio of 1:5 at 20°C. Protein denaturation - protein was extracted by the technique of Dyer 1 modified by Ironside and Love 2 and nitrogen content was measured by the colorimetric method proposed by Snow 3. After-coolingdrip - determined by the method recommended by the FAg 4.
~
PT
o
BT CT
o
3.5
2.5 18
:
.4 Q.
o
L~
16 14
o
o
m_ L
-- -- ~
•
/
• . . . . . .
m
12
/ ~ ,.~_p~ 2.O i_'2
•
1.5
PT ,~°CT
IO
I'
8
2
I
I
I
I
L
4
6
8
10
12
Storage 0 months Juiciness ,
PTo BTo CT A Drip - - - - - - P T e BTB CTA
Fig. 2 Degree of juiciness and percentage of a f t e r - c o o l i n g drip
Fig. 2 Degr# de succulence et pourcentage de jus apr#s exsudation
2-thiobarbituric acid value (TBA) - the method proposed by Witte et al. 5 was used. Dimethylamine (DMA) - we applied the technique proposed by Castell et al.e, modified by Moral et al. 7 Sensorial evaluation - we followed the norms established by the IF for selecting the taste panel 8 consisting of five trained persons, and for the taste, odour and texture evaluations we applied the method proposed by Howgate 9. and
discussion
The minces obtained by the three methods tested have different textures depending on the size and shape of the particles. This determines the rheological characteristics of the samples, as well as their behaviour during the storage. Newman1° studied the different types of particles in minces obtained by various methods, and found that when using the mincing method the particles had a uniform, globular shape, which resulted in a better defined texture and a lesser degree of destruction of tissue. The fish minces obtained by extrusion methods had irregularlyshaped particles and a higher degree of tissue destruction. Finally, the 'cutter' method (simultaneous cutting and homogenization) produces very small particles due to severe tissue destruction, giving minces with a very soft texture. The differences of the degree of tissue destruction have proven to be of great importance in the subsequent storage of these products.
A
5e -
,o-
30 --
BT
3.0
Results
Quality control
60 - -
~,/CT
.-..~BT
Tables 1 and 2 and Figs 1-7 show the values of the quality indices that were determined during the storage of the samples, and which were used to assess the suitability of the various methods of obtaining the minces.
" ~"" "~CT
zO
I
I
2
4
I
I
I
6
8
IO
Storoge, months Fig. 1 Protein solubility
Fig. I So/ub/l/td des protc~/nes
Volume 3 Number 1 January 1980
o "~PTI 12
Perhaps the most significant index is the soluble protein level (Fig. 1) obtained by the different methods. The mincing method (lot PT) showed higher values than the other two methods (lots CT and BT), and it was found that the protein solubility level remained high enough until the seventh month of
43
Table
1. Quality
indices
Tableau 1. indices de quart# Months of storage
Samples
pH
Protein denaturation, %
PT BT CT
7.00 7.04 7.00
66.5 50.00 46.10
13.8 7.57
PT BT CT
6.95 7.00 6.95
63 44.2 41.0
PT BT CT
6.93 6.75 6.85
PT BT CT
TBA Absorbance
DMA, mg N/100g
-
0.153 0.104
1.34 1.37 1.4
13.6 14.9 8.14
0.00 0.00 -
2.43 1.70 1.50
58 36.5 33.2
12.9 12.8 13.6
0.129 0.172 0.080
2.20 1.82 1.32
7.26 7.14 7.15
47.8 30.00 33.2
10.9 14.7
0.066 0.066 0.031
2.81 2.63 1.86
PT 8T CT
7.14 6.13 7.21
33.0 30.00 33.2
13.1 10.4
0.020 0.005 0.043
3.19 2,4 1.9
PT
BT CT
7.18 7.04 7.03
32.00 34.00 26.2
11.9 10.4
O.026 0.71
2.61 2.16
11
PT BT CT
7.10 7.01 7.11
22.00 35.4 29.5
14.2 16.5 11.0
0.120 0.086 O.132
3.12 2.63 2.24
12
PT BT CT
6.90 7.00 7.15
22.00 30.00 22.00
12.5 16.0 17.7
0.062 0.070 0.063
2.47 3.05 2.42
10
-
storage. However, in lots BT and CT the loss of protein solubility was strongly marked up to the fifth month of storage. This suggests that when more serious cell breakage occurs, as in lots BT and CT, there is a more marked actomyosin denaturation due, perhaps, to the fact that fine mincing releases a greater amount of intracellular liquids with enzymatic activity strong enough to induce protein denaturation. This
o
~
P
Drip, %
phenomenon has been observed before by Borderias et al. 1 in both whole and minced blue whiting. The protein denaturation levels become equalized from the tenth month of storage onwards, when the protein solubility indices reached values of about 30%. Paradoxically, the after-cooking drip values (Table 1 and Fig. 2) did not agree with protein denaturation values in the lot obtained by the 'cutter' method; in fact, with a lower level of soluble protein one would
T
0 1 ..PBTI 9
o
~.o-
~BT
°
2
PT
PT
--
o
BT
- - - - -- 13
CT
.....
I
~_ .__._.@._. _ _ .
a
PT
-a-._ CT
o
BT ------ a CT .....
\, \. "~CT I
L
2
4
I
l
6 8 Storage, months
I
I
I0
12
Fig. 3 Sensorial evaluation - degree of tissue firmness Fig. 3 Evaluation sensorielle - degr6 de fermet~ des tissus
44
I
I
1
1
I
I
2
4
6
8
IO
12
Storage , months Fig, 4 Sensorial evaluation - degree of tissue elasticity Fig. 4 Evaluation sensorielle - degr@ d'#lasticit@ des tissus
Revue Internationale du Froid
Table
2. T e x t u r o m e t r y
determined
by the
taste
panel
Table 2. E s t i m a t i o n de la t e x t u r e p a r un j u r y de d ~ g u s t a t i o n
Months of storage
Samples
Texture parameters
Juiciness
Firmness
SD
X
Elasticity
SD
Fibrousness
X
SD
X
Hardness
SD
Succulence
~
SO
SD
PT BT CT
1.5 2.0 1.9
1.3 0.5 0.0
3.16 2.5 1.2
0.7 0.86 0.7
2.0 2 -
0 0.7 -
2.3 2.2 1.45
0.~ 0.5 1
2.7 2.6 1.5
1 0.5 0.8
2.0 2 2.2
0.5 0.2 0.8
PT BT CT
2.6
0.4 1.2 0.6
3.0 2.2 1.3
0 0.7 0.5
2.0 1.0
0 0.5 0.4
2.4 1.8 1.0
0.9 0.7 0.5
2.8 1.8 1.3
0.5 0.3 0.7
1.8 2.5 1.7
0.6 1.0 0.4
PT BT CT
1.5 2.0 2.5
0.3 0.6 0.3
2.8 3.1 1.0
0.2 0.7 0.5
2.2 2.0 1.0
0.2 0.0 0.4
2.0 2.0 1.0
0.0 0.4 0.3
3.0 2.6 0.8
0.4 0.7 0.7
2,0 1.9 1.8
0.4 0.4 0.5
7
PT BT CT
2.0 2.3 3.5
0.3 0.6 0.6
2.1 2.4 0.3
0.4 0,4 0,4
2.0 0.9
0.5 0.6 0.6
2.5 2.1 0.9
0.4 0.5 0.5
2.5 2.1 0.3
0.4 0.6 0.4
1.9 2.4 2.5
1.7 0.6 0.6
8
PT
-
BT CT
2.6 .
0.2 0.4
2.3 2.5
0,4 0,3
0.3 0.0
2.5 2.6
0.5 0.4
1.5 1.4
0.5 0.5
.
0.3 0.5 .
2.5 2.0
.
2.5 .
.
PT BT CT
2.0 . .
0.4 . .
0.6
3.0
0.4
1.7
0.8
. .
2.0 . .
2.5
. .
. .
PT BT CT
1.8 2.6 .
0.8 0.6 .
2.2 2.2
0.2 0.2
3.2 2.7
0.8 0.3
1.3 2.0
0.2 0.4
.
2.6 2.2 .
PT BT CT
1.8 3.0 .
0.4 0.4 .
1.5 2.4
0.0 0.4
2.3 3.0
0.0 0.2
3.0 1.2
0.0 0.0
.
2.5 .
10
11
12
. 0.6
. 2.8
0.4
. . 0.8 0.4
. . 2.8 2.5
.
0.8 0.2
. 0.3 0.2
. 3.2 2.8
.
0.4 0.4
.
.
3
.
.
--
T
[] •-o
o
~
~/CT
...~ o.,/ -
2 -
~-'~.
8 (/)
PT BT -- ---CT .....
"~-
I
~"
0 o '~
I -
~-~ I
I
-cI ~
4
6
8
Storage,
o
I
I
IO
12
~
o ~
PT
~
o -- -- -,, . . . . .
BT CT
~
-
B ,
o
\
T ~
PT
I
I
I
I
I
I
2
4
6
8
I0
12
Storoqe,
months
months
Fig. 5 Sensorialevaluation - degreeof tissue hardness Fig. 5 Evaluation sensorielle - degr# de duret~ des tissus
V o l u m e 3 Num~ro 1 Janvier 1980
Fig. 6 Sensorialevaluation - degreeof succulence retained Fig. 6 Evaluation sensorielle - degr6 de succulence permanente
45
,~
16
~
t4
" z
12
o
PT
/.:<;_,-.-.-"
8 6 2
4
6
8
10
12
Storoge, months
Fig. 7 Dimethylaminevalues
by lots BT and CT. This fact might be due to the fact that the fish minces with very fine particles have a large number of broken cells, and/or to the change of the ionic conditions of the environment, which hinders the reaction that transforms trimethylamine oxide (OTMA) into DMA and formaldehyde. From the results of the experiments described above, it can be reasonably concluded that the mincing method, where it can be used and if the final product is convenient to use, is the most suitable to maintain a higher protein solubility during cold storage under the experimental conditions investigated.
Fig. 7 Ouantit# de dim#thylam/be
expect a higher amount of drip. This might be explained, perhaps, by the fact that the cutter produces a very fine-grained mince, with a larger number of particles per unit volume and, consequently, the adsorption surface is larger than in the lots obtained by other two methods. The texture measurements taken by the taste panel have shown, (Table 2 and Figs 2-6), that there was close correlation between protein denaturation and juiciness. The hardness, firmness and eleasticity values of the minces seemed to be more closely correlated with the particle characteristics than with actomyosin denaturation; no explanation can be given for the data on succulence. Sorensen 1 has investigated the rheologic properties of the fish minces and demonstrated also that their elasticity and hardness values increased during cold storage. No rancid taste was detected by the taste panel during storage, and the TBA level, as an indicator of peroxide decomposition, followed a very irregular course. The DMA behaviour was the inverse of that of protein denaturation. From Table 1 and Fig. 7 it can be seen that lot PT showed the highest D M A values, followed
46
References
1 2
3 4 5 6
7
Dyer,W.J., French, H. V., Snow, J, M. Proteins in fish muscle. I Extraction of protein fractions in fresh fish J Fish Res Bd Can 7 (1950) 585 Ironside, J. I. M., Love, R. M. Studies on protein denaturation in frozen fish. I Biological factors influencing the amounts of soluble and insoluble protein present in the muscle of the North Sea cod J Sci FoodAgrlb 9 (1958) 597 Snow, J. M. Proteins in fish muscle. II Colorimetricestimation of fish muscle protein J F/s Res Bd Can 7 (1950) 594 FAO - Circular (1972) Witte, W. C., Krause, C. F., Bailley, M. C. A new method for determining 2-thiobarbituric acid values of pork and beef during storage J Food Sci 35 (1970) 582 Castell, C. H., Smith, B., Dyer, W. J. Simultaneous measurements of tri-methylamineand dimethylaminein fish, and their use for estimating quality of frozen-stored gadoid fillets J Fish Res Bd Can 31 (1974) 383 Moral, A., Jim6nez-Colmenero, F., Borderias, A. J.
Contribuci6n a la determinaci6n conjunta de la dimetilamina y la trimetilaminapot el m6todo de Dyer en pescado congelado X V Intemadona/Congress of Refrigeration, Venice (1979) 8 Sanchez,A., Calvo, L., Moral, A. Cursos de ingenieriadel fdo Centro Experimentaldel Frio, Madrid (1972) 9 Howgate, P. Unpublished 10 Newman,D. D. Reforming of fish products with texture from frozen fish flesh (the Comitrol flake cutting system). The production and utilization of mechanicallyrecovered fish flesh (minced fish) Toffy Research Station, Aberdeen (April, 1976) 11 S~renaen,T. Effect of frozen storage on the functional properties of separated fish mince. The production and utilization of mechanicallyrecovered fish flesh (minced fish) Torry Research Station, Aberdeen (April, 1976)
International Journal of Refrigeration
Propri6t6s du merlan bleu cours de la conservation, apr s mise en hachis par diff6rentes m6thodes
au
Pour obtenir /ndustriellement des hach/s de poisson de diff#rentes esp#ces, /I est n#cessaire de connaTtre /e comportement ~ /'#tat congel# du bach/s, obtenu par dfff#rentes re#rhodes. Le hach/s de po/sson pr#par# ~ partir d'appareils ~ couteaux sera admissible pour les esp#ces qui peuvent #tre filet#es industriellement, ce qu/ permet d'ajouter de/'eau refroidie et des additifs au cours de/a pr#parat/on du
bach/s, en vue d'obten/r une texture fine. La pr#parat/on du hachis par broyage conv/ent aussi ~ ce genre d'esp#ces. L "extrusion peut #tre util/s#e pour un grand nombre d'esp#ces de po/ssons et peut #tre employ#e avec route m#thode de preparation du poisson. Au cours de la p#riode de conservation, jusqu'au lOe mois, /a diminution des prot#/nes so/ub/es est p/us fa/ble pour/e hachis de poisson obtenu avec des appareils ~ couteaux que pour/e hachis r#sultant du broyage ou de/'extrusion. Les #valuat/ons de jurys de d#gustation montrent que tous /es lots sont acceptables jusqu'au 7e mois de conservation; aude/& /e lot obtenu par/es apparei/s ~ couteaux devient /nacceptable, a/ors que /es r#sultats des deux autres lots sont loin de mainten/r /a qua//M opt/male.
The industrial objective of obtaining minced fish of different types necessitates investigating the frozen storage behaviour of minced fish obtained by different methods. The minced fish prepared by using the 'cutter method" would be advisable for those fish species that can be filleted industrially; this allows the addition of chilled water and many additives during the preparation of minced fish, resulting in a fine texture. The 'mincing method" is also appropriate for such species. Extrusion is applicable to a great number of types of fish, and can be used with any method of preparation of fish.
During the storage period, the decrease of soluble proteins appears to be less in minced fish obtained by the 'mincing method' than in minces obtained by the 'cutter' and 'extrusion' methods, upto the tenth month of storage. The taste panel evaluations show that all the lots were acceptable until the seventh month of storage, but from that time onwards the lot minced by the 'cutter' was not acceptable and the scores for the other two lots were far from optimal.
Introduction
fine structure; 2 - the mincing method; and 3 - the extrusion method. The latter gives larger particles than the preceeding methods, the size of which can be controlled by using different orifices.
Frozen minced fish is an industrially interesting product, but more information is needed on the storage behaviour of minced fish of different species, and the quality obtained by different methods. The method of mincing will affect the physical structure which determines both the organoleptic properties of the product and its behaviour towards freezing and subsequent storage. The purpose of the experimental study described here was to compare the advantages and disadvantages of each of the following methods of obtaining minces: 1 - the 'cutter' method (simultaneous cutting and homogenisation) which gives fish minces with a very The authors are at the Instituto del Frio, Ciudad Universitaria, Madrid - 3, Spain. This paper was first presented at the 5th International Congress of Food Science and Technology, Kyoto, Japan
42
0140-7007/80/010042-05 $02.00 © 1980 IPC Business Press Ltd. and IIR
As blue whiting (Micromesistius poutassou, Risso) is both abundant and commercially undervalued in Spain, we decided to use it in our experiments with a view to revaluating it.
Materials and methods Production and dressing of samples The blue whiting samples used in the experiments had been caught by the oceanographic ship 'Corn/de de Saavedra' on the Galician coastal shelf. After being sorted, the fishes were beheaded, gutted, thoroughly washed, and then divided into three lots as follows. Lot PT Samples were prepared by cutting fillets of fish in a conventional mincing machine with plate orifices of 5 mm; 12 kg of minced fish were sampled
International Journal of Refrigeration
into a number of trays containing about 0.5 kg each, for immediate freezing at -35 ° to -40°C in a multiplate 'Jackstone' freezer with a capacity of 524 kg per 24 h. All operations were carried out on the ship's deck at ambient temperature (14 ° to 16°C). The minced frozen fish was vacuum-packed in polyethylene bags with an 'Euvac 70/40' machine, and subsequently stored on board in a freezer room at -20°C. Lot BT Treated as for lot PT, except that the fish was not filleted and the mince was obtained by extrusion in a 'Baader Model 694' extruder. Lot CT The fish, after being prepared as indicated above, was frozen under the same conditions as the minces; they were subsequently taken to the Instituto del Frio (IF), where they were slowly thawed for 72 h at 0 ° to 2°C in a forced air circulation chamber. This fish, at a temperature between 0 ° and -2°C, was filleted in a room at 5°C. The fillets were minced in a Vivar HP 2.50/375 cutter, the process of simultaneous cutting and homogenisation being completed in 10 min at maximum speed; it was necessary to add 23% of water at 0°C to the product so as to avoid temperature rises and, consequent prot.ein denaturation. The freezing, packing and storage of samples was done as in the preceding lots. The samples were taken from the ship's cold chambers to the IF pilot plant at -20°C in a refrigerated lorry equipped with a compressor unit. All samples were stored at the same temperature (-20°C) for 12 months.
Every 1-2 months, samples were sawn into 1 to 1.5 cm blocks; these were used for quality control tests. These tests included measurements of: pH - determined on a macerated mince/distilled water mix in the ratio of 1:5 at 20°C. Protein denaturation - protein was extracted by the technique of Dyer 1 modified by Ironside and Love 2 and nitrogen content was measured by the colorimetric method proposed by Snow 3. After-coolingdrip - determined by the method recommended by the FAg 4.
~
PT
o
BT CT
o
3.5
2.5 18
:
.4 Q.
o
L~
16 14
o
o
m_ L
-- -- ~
•
/
• . . . . . .
m
12
/ ~ ,.~_p~ 2.O i_'2
•
1.5
PT ,~°CT
IO
I'
8
2
I
I
I
I
L
4
6
8
10
12
Storage 0 months Juiciness ,
PTo BTo CT A Drip - - - - - - P T e BTB CTA
Fig. 2 Degree of juiciness and percentage of a f t e r - c o o l i n g drip
Fig. 2 Degr# de succulence et pourcentage de jus apr#s exsudation
2-thiobarbituric acid value (TBA) - the method proposed by Witte et al. 5 was used. Dimethylamine (DMA) - we applied the technique proposed by Castell et al.e, modified by Moral et al. 7 Sensorial evaluation - we followed the norms established by the IF for selecting the taste panel 8 consisting of five trained persons, and for the taste, odour and texture evaluations we applied the method proposed by Howgate 9. and
discussion
The minces obtained by the three methods tested have different textures depending on the size and shape of the particles. This determines the rheological characteristics of the samples, as well as their behaviour during the storage. Newman1° studied the different types of particles in minces obtained by various methods, and found that when using the mincing method the particles had a uniform, globular shape, which resulted in a better defined texture and a lesser degree of destruction of tissue. The fish minces obtained by extrusion methods had irregularlyshaped particles and a higher degree of tissue destruction. Finally, the 'cutter' method (simultaneous cutting and homogenization) produces very small particles due to severe tissue destruction, giving minces with a very soft texture. The differences of the degree of tissue destruction have proven to be of great importance in the subsequent storage of these products.
A
5e -
,o-
30 --
BT
3.0
Results
Quality control
60 - -
~,/CT
.-..~BT
Tables 1 and 2 and Figs 1-7 show the values of the quality indices that were determined during the storage of the samples, and which were used to assess the suitability of the various methods of obtaining the minces.
" ~"" "~CT
zO
I
I
2
4
I
I
I
6
8
IO
Storoge, months Fig. 1 Protein solubility
Fig. I So/ub/l/td des protc~/nes
Volume 3 Number 1 January 1980
o "~PTI 12
Perhaps the most significant index is the soluble protein level (Fig. 1) obtained by the different methods. The mincing method (lot PT) showed higher values than the other two methods (lots CT and BT), and it was found that the protein solubility level remained high enough until the seventh month of
43
Table
1. Quality
indices
Tableau 1. indices de quart# Months of storage
Samples
pH
Protein denaturation, %
PT BT CT
7.00 7.04 7.00
66.5 50.00 46.10
13.8 7.57
PT BT CT
6.95 7.00 6.95
63 44.2 41.0
PT BT CT
6.93 6.75 6.85
PT BT CT
TBA Absorbance
DMA, mg N/100g
-
0.153 0.104
1.34 1.37 1.4
13.6 14.9 8.14
0.00 0.00 -
2.43 1.70 1.50
58 36.5 33.2
12.9 12.8 13.6
0.129 0.172 0.080
2.20 1.82 1.32
7.26 7.14 7.15
47.8 30.00 33.2
10.9 14.7
0.066 0.066 0.031
2.81 2.63 1.86
PT 8T CT
7.14 6.13 7.21
33.0 30.00 33.2
13.1 10.4
0.020 0.005 0.043
3.19 2,4 1.9
PT
BT CT
7.18 7.04 7.03
32.00 34.00 26.2
11.9 10.4
O.026 0.71
2.61 2.16
11
PT BT CT
7.10 7.01 7.11
22.00 35.4 29.5
14.2 16.5 11.0
0.120 0.086 O.132
3.12 2.63 2.24
12
PT BT CT
6.90 7.00 7.15
22.00 30.00 22.00
12.5 16.0 17.7
0.062 0.070 0.063
2.47 3.05 2.42
10
-
storage. However, in lots BT and CT the loss of protein solubility was strongly marked up to the fifth month of storage. This suggests that when more serious cell breakage occurs, as in lots BT and CT, there is a more marked actomyosin denaturation due, perhaps, to the fact that fine mincing releases a greater amount of intracellular liquids with enzymatic activity strong enough to induce protein denaturation. This
o
~
P
Drip, %
phenomenon has been observed before by Borderias et al. 1 in both whole and minced blue whiting. The protein denaturation levels become equalized from the tenth month of storage onwards, when the protein solubility indices reached values of about 30%. Paradoxically, the after-cooking drip values (Table 1 and Fig. 2) did not agree with protein denaturation values in the lot obtained by the 'cutter' method; in fact, with a lower level of soluble protein one would
T
0 1 ..PBTI 9
o
~.o-
~BT
°
2
PT
PT
--
o
BT
- - - - -- 13
CT
.....
I
~_ .__._.@._. _ _ .
a
PT
-a-._ CT
o
BT ------ a CT .....
\, \. "~CT I
L
2
4
I
l
6 8 Storage, months
I
I
I0
12
Fig. 3 Sensorial evaluation - degree of tissue firmness Fig. 3 Evaluation sensorielle - degr6 de fermet~ des tissus
44
I
I
1
1
I
I
2
4
6
8
IO
12
Storage , months Fig, 4 Sensorial evaluation - degree of tissue elasticity Fig. 4 Evaluation sensorielle - degr@ d'#lasticit@ des tissus
Revue Internationale du Froid
Table
2. T e x t u r o m e t r y
determined
by the
taste
panel
Table 2. E s t i m a t i o n de la t e x t u r e p a r un j u r y de d ~ g u s t a t i o n
Months of storage
Samples
Texture parameters
Juiciness
Firmness
SD
X
Elasticity
SD
Fibrousness
X
SD
X
Hardness
SD
Succulence
~
SO
SD
PT BT CT
1.5 2.0 1.9
1.3 0.5 0.0
3.16 2.5 1.2
0.7 0.86 0.7
2.0 2 -
0 0.7 -
2.3 2.2 1.45
0.~ 0.5 1
2.7 2.6 1.5
1 0.5 0.8
2.0 2 2.2
0.5 0.2 0.8
PT BT CT
2.6
0.4 1.2 0.6
3.0 2.2 1.3
0 0.7 0.5
2.0 1.0
0 0.5 0.4
2.4 1.8 1.0
0.9 0.7 0.5
2.8 1.8 1.3
0.5 0.3 0.7
1.8 2.5 1.7
0.6 1.0 0.4
PT BT CT
1.5 2.0 2.5
0.3 0.6 0.3
2.8 3.1 1.0
0.2 0.7 0.5
2.2 2.0 1.0
0.2 0.0 0.4
2.0 2.0 1.0
0.0 0.4 0.3
3.0 2.6 0.8
0.4 0.7 0.7
2,0 1.9 1.8
0.4 0.4 0.5
7
PT BT CT
2.0 2.3 3.5
0.3 0.6 0.6
2.1 2.4 0.3
0.4 0,4 0,4
2.0 0.9
0.5 0.6 0.6
2.5 2.1 0.9
0.4 0.5 0.5
2.5 2.1 0.3
0.4 0.6 0.4
1.9 2.4 2.5
1.7 0.6 0.6
8
PT
-
BT CT
2.6 .
0.2 0.4
2.3 2.5
0,4 0,3
0.3 0.0
2.5 2.6
0.5 0.4
1.5 1.4
0.5 0.5
.
0.3 0.5 .
2.5 2.0
.
2.5 .
.
PT BT CT
2.0 . .
0.4 . .
0.6
3.0
0.4
1.7
0.8
. .
2.0 . .
2.5
. .
. .
PT BT CT
1.8 2.6 .
0.8 0.6 .
2.2 2.2
0.2 0.2
3.2 2.7
0.8 0.3
1.3 2.0
0.2 0.4
.
2.6 2.2 .
PT BT CT
1.8 3.0 .
0.4 0.4 .
1.5 2.4
0.0 0.4
2.3 3.0
0.0 0.2
3.0 1.2
0.0 0.0
.
2.5 .
10
11
12
. 0.6
. 2.8
0.4
. . 0.8 0.4
. . 2.8 2.5
.
0.8 0.2
. 0.3 0.2
. 3.2 2.8
.
0.4 0.4
.
.
3
.
.
--
T
[] •-o
o
~
~/CT
...~ o.,/ -
2 -
~-'~.
8 (/)
PT BT -- ---CT .....
"~-
I
~"
0 o '~
I -
~-~ I
I
-cI ~
4
6
8
Storage,
o
I
I
IO
12
~
o ~
PT
~
o -- -- -,, . . . . .
BT CT
~
-
B ,
o
\
T ~
PT
I
I
I
I
I
I
2
4
6
8
I0
12
Storoqe,
months
months
Fig. 5 Sensorialevaluation - degreeof tissue hardness Fig. 5 Evaluation sensorielle - degr# de duret~ des tissus
V o l u m e 3 Num~ro 1 Janvier 1980
Fig. 6 Sensorialevaluation - degreeof succulence retained Fig. 6 Evaluation sensorielle - degr6 de succulence permanente
45
,~
16
~
t4
" z
12
o
PT
/.:<;_,-.-.-"
8 6 2
4
6
8
10
12
Storoge, months
Fig. 7 Dimethylaminevalues
by lots BT and CT. This fact might be due to the fact that the fish minces with very fine particles have a large number of broken cells, and/or to the change of the ionic conditions of the environment, which hinders the reaction that transforms trimethylamine oxide (OTMA) into DMA and formaldehyde. From the results of the experiments described above, it can be reasonably concluded that the mincing method, where it can be used and if the final product is convenient to use, is the most suitable to maintain a higher protein solubility during cold storage under the experimental conditions investigated.
Fig. 7 Ouantit# de dim#thylam/be
expect a higher amount of drip. This might be explained, perhaps, by the fact that the cutter produces a very fine-grained mince, with a larger number of particles per unit volume and, consequently, the adsorption surface is larger than in the lots obtained by other two methods. The texture measurements taken by the taste panel have shown, (Table 2 and Figs 2-6), that there was close correlation between protein denaturation and juiciness. The hardness, firmness and eleasticity values of the minces seemed to be more closely correlated with the particle characteristics than with actomyosin denaturation; no explanation can be given for the data on succulence. Sorensen 1 has investigated the rheologic properties of the fish minces and demonstrated also that their elasticity and hardness values increased during cold storage. No rancid taste was detected by the taste panel during storage, and the TBA level, as an indicator of peroxide decomposition, followed a very irregular course. The DMA behaviour was the inverse of that of protein denaturation. From Table 1 and Fig. 7 it can be seen that lot PT showed the highest D M A values, followed
46
References
1 2
3 4 5 6
7
Dyer,W.J., French, H. V., Snow, J, M. Proteins in fish muscle. I Extraction of protein fractions in fresh fish J Fish Res Bd Can 7 (1950) 585 Ironside, J. I. M., Love, R. M. Studies on protein denaturation in frozen fish. I Biological factors influencing the amounts of soluble and insoluble protein present in the muscle of the North Sea cod J Sci FoodAgrlb 9 (1958) 597 Snow, J. M. Proteins in fish muscle. II Colorimetricestimation of fish muscle protein J F/s Res Bd Can 7 (1950) 594 FAO - Circular (1972) Witte, W. C., Krause, C. F., Bailley, M. C. A new method for determining 2-thiobarbituric acid values of pork and beef during storage J Food Sci 35 (1970) 582 Castell, C. H., Smith, B., Dyer, W. J. Simultaneous measurements of tri-methylamineand dimethylaminein fish, and their use for estimating quality of frozen-stored gadoid fillets J Fish Res Bd Can 31 (1974) 383 Moral, A., Jim6nez-Colmenero, F., Borderias, A. J.
Contribuci6n a la determinaci6n conjunta de la dimetilamina y la trimetilaminapot el m6todo de Dyer en pescado congelado X V Intemadona/Congress of Refrigeration, Venice (1979) 8 Sanchez,A., Calvo, L., Moral, A. Cursos de ingenieriadel fdo Centro Experimentaldel Frio, Madrid (1972) 9 Howgate, P. Unpublished 10 Newman,D. D. Reforming of fish products with texture from frozen fish flesh (the Comitrol flake cutting system). The production and utilization of mechanicallyrecovered fish flesh (minced fish) Toffy Research Station, Aberdeen (April, 1976) 11 S~renaen,T. Effect of frozen storage on the functional properties of separated fish mince. The production and utilization of mechanicallyrecovered fish flesh (minced fish) Torry Research Station, Aberdeen (April, 1976)
International Journal of Refrigeration