Squid Mantle Research Articles

Effect of storage at 0 °C on mantle proteins and functional properties of jumbo squid

SummaryEffect of iced storage of jumbo squid mantle with fin on gelling capacity and changes in protein fractions and functional properties of jumbo squid mantle protein during storage at 0 °C were assessed. Most values of texture variables in gels did not significantly change during storage. On average, they were: strength 65.07 ± 4.71 N; elasticity 68.14 ± 5.3%, fracturability 52.97 ± 1.28 N and cohesiveness 36.6 ± 0.1%. Protein solubility increased more than 40%. Whippability increased during storage for 16 days at 0 °C (81–162%), as did foam stability (73–94%). Results suggest that iced squid mantle protein is a suitable ingredient for food products where these functional properties are desirable. Muscle fibres of squid mantle undergo various changes during storage. At 0 °C, they are disrupted, whereas at −20 °C, they aggregate and develop empty spaces in the tissue.

Effect of thermal process on connective tissue from jumbo squid ( Dosidicus gigas) mantle

The effect of two thermal treatments (fast freezing at −40 °C and vapor cooking at 100 °C) on connective tissue extract (CTE) from jumbo squid ( Dosidicus gigas) was investigated. Samples of CTE frozen at −40 °C were taken at 0, 3, 5 and 12 min. Also CTE was cooked at 100 °C and samples were taken at 0, 1, 2.5 and 5 min. Light microscopic observations of CTE after 12 min of freezing showed rupture of fibres. The CTE fibres showed agglutination during cooking time. The CTE insoluble fraction increased with freezing and cooking time. Maximum zeta potential value of untreated CTE was detected at pH 5.0 at +30 mV, meanwhile in the frozen CTE it was detected at pH 7.0 at +30 mV and two peaks (at pH 5.5 and 9.0) were observed at +20 mV in the cooked CTE. One endothermic peak was found at 105.9 °C in the untreated CTE, while in the frozen and cooked CTE the endothermic peaks were found at lower temperatures and enthalpies. Electrophoresis analysis of untreated CTE showed three bands. In the frozen CTE two bands appeared above 200 kDa, and in the cooked CTE, a 45 kDa band disappeared. These results suggest that during freezing and cooking processes there were modifications to molecular bonds that hold the integrity of the structure of the connective tissue of the jumbo squid mantle.

Postmortem Biochemical Behavior of Giant Squid (Dosidicus gigas) Mantle Muscle Stored in Ice and its Relation with Quality Parameters

Several freshness and spoilage indicators were monitored to characterize the postmortem biochemistry of giant squid (Dosidicus gigas) mantle muscle. Squid samples were obtained directly from the sea and kept at 0 degrees C during a 15-d storage period. Data at zero time were obtained from cryogenically frozen samples at time of capture. The adenosine 5'-triphosphate (ATP) degradation followed a different pattern as compared with that from fish species. ATP was almost completely depleted at 24-h postcatch from 6.54 to <1 micromol/g, while at the same time Hx was the predominant catabolite with a concentration of 4 mumol/g, reaching 6.85 micromol/g at day 15. K-value data followed a logarithmic pattern with time instead of a linear one, with no change after day 3, thus reducing its suitability as a freshness index. The coefficient Hx/AMP seems to be an adequate alternative for this purpose due to its constant increment with time. The high NH4Cl content in mantle muscle (461.3 +/- 24.5 mg of NH4(+)/100 g) derived from its physiological importance for the species compromises the use of the distillation step of the TVB-N analysis commonly used as a spoilage index. This fact explains why the initially high value of TVB-N detected in mantle muscle (243.7 mg N/100 g) did not correlate with the initial low TMA-N content (1.5 +/- 0.1 mg/100 g of muscle). The results suggested that under the experimental conditions the shelf life of squid exceeds 15 d.

Relationship between Postmortem Changes and Browning of Boiled, Dried, and Seasoned Product Made from Japanese Common Squid (Tedarodes pacificus) Mantle Muscle

To clarify the process that possibly causes discoloration in boiled, dried, and seasoned squid products ("sakiika" or "ikakun" in Japanese), we investigated the relationship of squid freshness with the rate of browning using the boiled, freeze-dried, and ground squid product model. ATP and its related compounds in Japanese common squid (Tedarodes pacificus) decomposed gradually during storage, yielding hypoxanthine and ribose at 24 h postmortem. The browning rate of the model during preservation as revealed by the increase of the b* value showed a high coefficient in the linear regression against ribose content (R2 = 0.767). Only the model made from the squid stored for 24 h postmortem turned brown. These results strongly suggest that ribose produced during storage plays a major role in the browning of dried and seasoned squid products.

CHANGES IN MYOFIBRILLAR PROTEINS AND LIPIDS OF SQUID (ILLEX ARGENTINUS) DURING FROZEN STORAGE

The biochemical properties of actomyosin (AM) and lipid composition of the mantle from frozen-stored whole squid were investigated. Irrespective of the sex of specimens, during the first months of storage, there was a trend of decreased protein solubility, reduced viscosity and enzymatic activities of AM. A significant decrease (P < 0.05) in the relative percentage of the myosin heavy chain and a significant increase (P < 0.05) in those of paramyosin and the 155-kDa component were also observed. After freezing, phospholipids (PL), sterols (ST) and triacylglycerols (TAG) represented 38.6, 29.1 and 21.2%, respectively, of total lipids (TL) from the mantle of male squid. Free fatty acids (FFA) plus diacylglycerols constituted only 11% of TL. TL extract from the mantle of female squid had a higher percentage of PL and had lower ST. In the frozen-stored male and female squid, TAG were hydrolyzed earlier than PL. At zero time of storage, the relative percentages of saturated and unsaturated fatty acid in TL extracts from the mantle of male and female squid were 39.1, 59.2 and 38.7, 61.1, respectively. Irrespective of sex, the saturated FA fraction significantly (P < 0.05) decreased and the unsaturated one significantly (P < 0.05) increased after 8 months of frozen storage.

Solubilization of Myofibrils and Inhibition of Autolysis of Squid Mantle Muscle by Sodium Citrate

ABSTRACT: The effects of organic salts (sodium (Na)‐citrate, Na‐gluconate, and Na‐succinate) on the solubilization of myofibrillar proteins and the inhibition of autolysis of squid mantle muscle were investigated. All of the organic compounds dissolved myofibrils as NaCl did. Na‐citrate showed the strongest ability with half dissolving at 0.06 M. Half dissolving by Na‐gluconate, Na‐succinate, and NaCl were 0.27, 0.21, and 0.27 M, respectively. Dissolving myofibrils by Na‐citrate was not accompanied by the acceleration of autolysis. Na‐citrate above 0.25 M almost completely inhibited the autolysis. The inhibition of autolysis by Na‐gluconate and Na‐succinate was much less than that of Na‐citrate. Consequently, it was concluded that Na‐citrate was the organic salt to dissolve squid myofibrils without inducing autolysis.

EFFECT OF REFRIGERATED STORAGE ON PROTEOLYTIC ACTIVITY AND PHYSICOCHEMICAL AND MICROSTRUCTURAL PROPERTIES OF GIANT SQUID (DOSIDICUS GIGAS) MANTLE MUSCLE

ABSTRACT Giant squid (Dosidicus gigas) is abundant along the Pacific Coast of Mexico. It possesses a high proteolytic activity that makes it a low‐quality food material. Squid mantle endogenous proteases were partially characterized; physicochemical and structural changes during storage at 4C were also examined. High proteolytic activity was observed at acidic and alkaline pH values. Proteases were strongly inhibited by leupeptine and pepstatin A, as well as by phenyl methyl sulfonyl fluoride, indicating the possible presence of serine, cysteine and metal proteases. Myosin heavy chain was degraded during storage, as shown on sodium dodecyl sulfate–polyacrylamide gel electrophoresis patterns, resulting in a significant decrease (P &lt; 0.001) in muscle water‐holding capacity, texture and gelling capacity. Muscle deterioration was evident in scanning electron micrographs, where the initial compact structure loosened during storage.

Partial Characterization of Protease Activity in Squid (Todaropsis eblanae) Mantle: Modification by High-pressure Treatment

ABSTRACT: Optimal conditions for proteolytic activity in both nonpressurized and pressurized (300 MPa, 7°C, 20 min) squid (Todaropsis eblanae) muscle occurred at acid pH levels (pH 3) over a broad range of temperatures. Pressure treatment did not modify optimal pH and temperatures but did increase proteolytic activity. The acid cysteine proteases, and to a lesser extent the acid serine proteases, were the enzymes mainly affected by the high-pressure treatment. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was indicative of increased protein hydrolysis by pressurization. Myosin heavy chain in both nonpressurized and pressurized squid was degraded at all the temperatures tested, but actin was susceptible only to proteolysis in the pressure-treated muscle at 7°C and 40°C. This behavior was not observed at 55°C.

Effect of soy sauce on the antioxidative capacity of the gelatin gel food ‘Nikogori’ measured using the chemiluminescence method

Oxygen-related free radicals have been suggested as a cause of aging and various diseases, for example, various cancers and rheumatoid arthritis. Because of this a radical scavenger as an antioxidant has been sought in many foods. 'Nikogori' gelatin gel from cooked fish is a traditional food in Japan. Recently, 'Nikogori' has been noted as a readily consumed food for the elderly and those with medical problems associated with swallowing. In this study we report that the 'Nikogori' gelatin gels made from the collagen in various meats have a high peroxyl radical scavenging capability as the antioxidative capacity using the chemiluminescence method and the order of the strength of antioxidative capacity (IC(50) value) was the Japanese common squid mantle meat (0.163%) > flatfish (marbled sole) meat (0.534%) > chicken wing meat (0.585%) > beef shin meat (0.655%) > yellowtail meat (0.659%) > chub mackerel meat (0.789%). Furthermore, when soy sauce was added to the 'Nikogori' gelatin gel, the antioxidative capacity increased markedly to 0.098% of IC(50) value of yellowtail, 0.165% of chicken, 0.182% of flatfish and 0.252% of chub mackerel.

Physico-chemical and functional properties of myofibrillar proteins from different species of molluscs

The physico-chemical and functional properties of myofibrillar proteins from scallop ( Zygochlamys patagonica), bivalve molluscs ( Aulacomya ater ater), and squid ( Illex argentinus) were investigated. Actomyosins were studied by SDS-PAGE, Mg 2+-(Ca 2+-dependent) ATPase activity, reduced viscosity, and surface hydrophobicity determinations. The emulsion capacity (EC) of both soluble protein extracts and actomyosins was also determined. Densitometric analysis of the SDS-PAGE 10% gels showed that in comparison with the actomyosin from striated muscle of scallop, the actomyosins of Aulacomya, squid, and smooth plus striated muscle of scallop have a significant higher relative percentage of paramyosin and a lower relative percentage of myosin. The reduced viscosity of actomyosin from both striated and smooth plus striated adductor muscle of scallop was significantly lower than that of squid and Aulacomya. No significant differences were observed in the enzymatic activity of the actomyosins analysed. Surface hydrophobicity and EC of actomyosin from striated muscle of Aulacomya were lower than those corresponding to actomyosin of the other species. The highest values of EC were observed in extracts of squid mantle. In addition, the EC of the extracts was significantly higher than the EC of their respective actomyosins.

Preparation of heavy meromyosin from the autolyzed squid mantle muscle homogenate

Incubation of squid mantle muscle homogenate caused a selective cleavage of myosin into heavy meromyosin (HMM) and light meromyosin (LMM). HMM was isolated from the incubated homogenate by using ammonium sulfate fractionation. The purified HMM retained two types of light chain components. Its Mg2+-ATPase activity with or without F-actin showed a Ca=-sensitivity. HMM was cleaved into subfragment-1 and subfragment-2 upon chymotryptic digestion with or without Ca2+, possessing different light chain composition. Two types of light chain component were kept intact when digested in the presence of Ca2+, Ca2+ stabilized HMM especially in a bound form to F-actin.

Functional importance of Ca 2+-deficient N-terminal lobe of molluscan troponin C in troponin regulation

Ca 2+-binding sites I and II in the N-terminal lobe of molluscan troponin C (TnC) have lost the ability to bind Ca 2+ due to substitutions of the amino acid residues responsible for Ca 2+ liganding. To evaluate the functional importance of the Ca 2+-deficient N-terminal lobe in the Ca 2+-regulatory function of molluscan troponin, we constructed chimeric TnCs comprising the N-terminal lobes from rabbit fast muscle and squid mantle muscle TnCs and the C-terminal lobe from akazara scallop TnC, TnC RA, and TnC SA, respectively. We characterized their biochemical properties as compared with those of akazara scallop wild-type TnC (TnC AA). According to equilibrium dialysis using 45Ca 2+, TnC RA, and TnC SA bound stoichiometrically 3 mol Ca 2+/mol and 1 mol Ca 2+/mol, respectively, as expected from their primary structures. All the chimeric TnCs exhibited difference-UV-absorption spectra at around 280–290 nm upon Ca 2+ binding and formed stable complexes with akazara scallop troponin I, even in the presence of 6 M urea, if Ca 2+ was present. However, when the troponin complexes were constructed from chimeric TnCs and akazara scallop troponin T and troponin I, they showed different Ca 2+-regulation abilities from each other depending on the TnC species. Thus, the troponin containing TnC SA conferred as high a Ca 2+ sensitivity to Mg-ATPase activity of rabbit actomyosin–akazara scallop tropomyosin as did the troponin containing TnC AA, whereas the troponin containing TnC RA conferred virtually no Ca 2+ sensitivity. Our findings indicate that the N-terminal lobe of molluscan TnC plays important roles in molluscan troponin regulation, despite its inability to bind Ca 2+.

Cloning and nucleotide sequence of a novel 28-kDa protein from the mantle muscle of the squid Todarodes pacificus with homology to tropomyosin

In recent studies, we found autodegradation of collagen from the mantle muscle of the squid Todarodes pacificus and also that the 28- and 25-kDa proteins are closely related to this phenomenon [Connect. Tissue Res. 45 (2004) 109–121]. We obtained partial sequences of three internal portions of this protein, which suggested that 25-kDa protein is a partially degraded form of the 28-kDa protein. We determined the full cDNA sequence of this protein by the degenerate polymerase chain reaction (PCR) using the information of amino acid sequences. The deduced amino acid sequence corresponding to the 212-bp cDNA contained all of the amino acid identified from the 28-kDa protein. Rapid amplification of cDNA ends (RACE) and squid mantle muscle RNA allowed cloning of the full 522-bp sequence, corresponding to a protein of 174 amino acids. A database search indicated that this is a new protein that shares 27–34% identity with tropomyosins from various animals. Structural prediction suggested that it possesses heptad repeats that form coiled-coil structures. We expressed a recombinant protein encoded by the 212-bp cDNA in Escherichia coli and used it to generate a polyclonal antibody. Western blotting with this antibody showed that the 28-kDa protein is expressed in fin, tentacle, and mantle muscle, but not in liver.

The effect of vitamin E on growth, survival and hepatopancreas structure of the Argentine red shrimp Pleoticus muelleri Bate (Crustacea, Penaeidea)

Two trials were conducted to evaluate the growth, survival and hepatopancreas histology of the Argentine red shrimp Pleoticus muelleri (Bate, 1888) fed different levels of vitamin E and butylated hydroxytoluene (BHT) in a semipurified diet. The diets contained 0, 100, 600 or 1500 mg vitamin E kg-1 and 16 mg BHT kg-1 diet (trial 1) and 0, 1250, 1500, 1750 or 2000 mg vitamin E kg-1 diet, squid mantle and vitamin-free diet as a control (trial 2). After 30 days (trial 1), survival ranged between 43% and 64%, and the percentage weight gain of the shrimp varied from 22% to 31% with no significant differences among treatments (P<0.05). After 40 days (trial 2), survival of shrimp fed the diet with no vitamin E and squid mantle was significantly lower (62%) than the other treatment (86-90%). Shrimp fed diets containing vitamin E from 1250 to 1750 mg kg-1 exhibited increased weight gain (34-65%); however, a significant difference was observed for shrimp fed the diet containing 2000 mg kg-1. Histological results yielded differences among treatments. In shrimp fed 1750 mg kg-1 of vitamin E, the functional morphology of the organ was normal, with abundant secretion in the tubules. Signs of malnourishment such as cellular and nuclear retraction, desquamation of cells and hipertrofia, were evident in the hepatopancreas of shrimp fed the other diets. The results indicate that optimal vitamin E requirement for P. muelleri under the present experimental conditions appears to be approximately 1750 mg vitamin E kg-1 diet.

Microstructure and fracture characteristics of squid mantle in which mode of transportation differs.

Microstructure and fracture characteristics of squid mantle in which mode of transportation differs.

Antioxidant activity in hepatopancreas of the shrimp (Pleoticus muelleri) by electron paramagnetic spin resonance spectrometry.

Free radical scavenging properties of hepatopancreas extracts of Pleoticus muelleri were evaluated by electron paramagnetic spin resonance spectrometry methods (EPR) against the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The present study was carried out to characterize different physiological stages of the shrimp under environmental and nutritional stress, evaluating the effect on growth, survival, and functional morphology of the hepatopancreas. Feeding trials were carried out on juveniles (1 g initial weight) held in aquaria. Each diet, with different concentrations of vitamins A and E, was tested in triplicate groups during 25 days. The control groups were fed with fresh squid mantle and with a vitamin-free diet. For all of the diets, the extracts exhibited strong DPPH radical scavenging activity, suggesting that the tissue is a powerful natural antioxidant. Individuals fed with different concentrations of vitamin E showed the strongest effect on the DPPH radicals, reducing the DPPH radicals to 50%, after an incubation period of 3 min. In contrast, the extracts of control animals, fed with squid mantle, had the weakest antioxidant activity (4%). These data indicated that the presence of vitamin E in the diet can provide immediate protection against free radicals.

Identification of high molecular weight proteins in squid muscle by Western blotting analysis and postmortem rheological changes.

The high molecular weight protein connectin (also called titin) in Japanese common squid (Todarodes pacificus) mantle muscle was identified by western blotting analysis with 3B9, the mouse anti-chicken skeletal muscle connectin monoclonal antibody. Similarly to vertebrate samples, there exists connectin in invertebrate squid mantle muscle, and the amino acid sequences are assumed to resemble those present in the A band of vertebrate connectin, judging by the specificity of 3B9. Moreover, the connectin in squid muscle migrated in this study as a closely spaced doublet of alpha and beta (titins 1 and 2). Between 5 and 7 h post-mortem, the SDS PAGE patterns of the squid sample indicated a change of the doublet bands into a single beta-connectin band. Simultaneously, the rheological properties of the squid muscle changed substantially. This degradation of alpha-connectin into beta-connectin in the muscle can explain the critical change that occurs during the post-mortem tenderization of squid muscle.

Mercury in the marine food chain in the Southern Ocean at Macquarie Island: an analysis of a top predator, Patagonian toothfish ( Dissostichus eleginoides ) and a mid-trophic species, the warty squid ( Moroteuthis ingens )

The characteristics and habitat of the Patagonian toothfish (Dissostichus eleginoides) are typical of fish that accumulate high concentrations of mercury. In this study, mercury determinations were made on samples of muscle tissue from Macquarie Island toothfish and the Southern Ocean deepwater warty squid (Moroteuthis ingens). The analysis of mercury in the biological tissues was made by cold vapour-atomic absorption spectrometry following acid digestion. Performance of the analytical procedure was assessed by analysis of certified reference material (DORM-2, dogfish muscle). Mercury concentrations of 16 Macquarie Island toothfish ranged from 0.12 mg kg–1 (550 g, 381 mm TL) to 0.59 mg kg–1 (6,100 g, 823 mm TL), with a mean concentration of 0.33±0.12 mg kg–1. A significant correlation was found between mercury and either toothfish weight or total length. The fish analysed were juveniles, which suggests that larger individuals would have higher mercury concentrations well exceeding food standard code limits for mercury in fish (typically 0.5 mg kg–1). Warty squid, also from around Macquarie Island, had a low mean mercury concentration of 0.086 mg kg–1 in mantle tissue; no significant correlation existed between mercury concentration and either squid mantle length or total weight. It is postulated that the squid have a mechanism, possibly involving the digestive gland, that prevents bioaccumulation of mercury in the mantle, and presumably other body tissues.

Influence of Endogenous Proteases and Transglutaminase on Thermal Gelation of Salted Squid Muscle Paste

ABSTRACT: Thermal gelation of salted squid mantle muscle paste was studied in relation to endogenous proteases and transglutaminase. Myosin in the paste was preferentially degraded into 130‐kDa and 90‐kDa fragments at an optimum temperature of 30 °C. Degradation was inhibited with EDTA or 1,10 phenanthroline, suggesting the presence of metalloproteases. Myosin degradation was markedly reduced above 40 °C. Although 10 mM Ca2+ increased cross‐linking of myosin heavy chains by activating the endogenous transglutaminase, setting effect on thermal gelation of the paste was offset by degradation induced by simultaneously activated calpains. Ca2+ and the alpain inhibitor, E64, significantly improved the breaking strength and strain of thermal gels preincubated at 40 °C.

Functional and Thermal Gelation Properties of Squid Mantle Proteins Affected by Chilled and Frozen Storage

ABSTRACT: Fresh squid (Loligo vulgaris) mantles that underwent chilled and frozen storage were studied for their ability to form thermal gels as well as the effects of changes to the functional and chemical properties of the muscle proteins during storage. Assays of protein extractability in 5% NaCl, apparent viscosity, autolytic activity, and SDS‐PAGE (of the soluble fraction) were carried out periodically. After 4 d of chilled storage, there was a significant drop in protein functionality that negatively affected the thermal gelation profile. The rate of proteolysis remained very high throughout frozen storage, however functional properties and thermal behavior remained very stable.