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Collagen is the major connective tissue (CT) protein and one of the main constituents of the jumbo squid (Dosidicus gigas). Therefore, physicochemical changes of pepsin-solubilized collagen (PSC) and insoluble collagen (IC) were studied after cooking (100°C/30 min) of muscle (mantle, fins, and arms). Different pyridinoline (Pyr) contents (the major cross-linking molecule in collagen fibers) were found in the fresh muscle of the three anatomical regions. After the cooking process, a decrease from 10 to 30% in the thermal resistance of collagen was observed, depending on the anatomical region and fraction evaluated. Furthermore, the electrophoretic profile, Fourier transform infrared (FTIR) spectroscopy, and the amino-acid profile revealed that structural changes occurred in the two different collagen fractions caused by the thermal process, and the changes were greater in the mantle. Under the conditions applied in this study, collagen fractions from the squid arms showed more stability during the cooking process due to the high cross-linking degree of their fibers.

The giant squid (Dosidicus gigas) has been proposed as raw material to obtain myofibrillar protein concentrates. However, it has been observed that colloidal systems formed from squid proteins have limited stability. Therefore, the isolation and characterization of the actomyosin-paramyosin isolated (API) complex were performed, because they are the main proteins to which functionality has been attributed.; Results: Densitogram analysis revealed 45% of actin, 38% of myosin and 17% of paramyosin. The amino acid profile indicates a higher proportion of acidic amino acids, which gives a higher negative charge; this was supported by the zeta potential. Total sulfhydryl (TSH) content was lower compared with proteins of other aquatic species.; Conclusion: The higher percentage of actin in relation to myosin, the presence of paramyosin, as well as the low content of sulfhydryl groups, could comprise the main causes of the low technological functional property of proteins from D. gigas mantle. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

The antibacterial activity of low-density polyethylene/adhesive resin (10%)/epigallocatechin gallate (0.03, 0.5, 5, and 10%) extrusion cast films were evaluated against Staphylococcus aureus (gram positive) and Pseudomonas sp. (gram negative) via direct contact and in solid and liquid culture media. The epigallocatechin gallate concentration in the active films was established per the in vitro antibacterial analysis of pure epigallocatechin gallate against S. aureus and Pseudomonas sp. The epigallocatechin gallate migration profile and concentration required to inhibit bacterial growth in broth were determined. In addition, the effects of epigallocatechin gallate and adhesive resin on the mechanical, color, and thermal film properties were investigated. The results indicate that pure epigallocatechin gallate inhibited the growth of both bacteria. However, only the films with 10 wt% epigallocatechin gallate (with and without adhesive resin) induced morphological changes and inhibited the growth of S. aureus (p

Chymotrypsin was purified from jumbo squid hepatopancreas (HP) with 2.4-fold and yield 1.9%, and characterized with a molecular weight of 31 kDa, as estimated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE). Chymotrypsin effect over collagen extracted from the mantle, fins and arms of the jumbo squid was evaluated. The enzyme exhibited the maximum activity at pH 7 and 65°C using Suc-Ala-Ala-Pro-Phe-p-nitroanilide (SAAPNA) as a substrate and it was identified using the specific inhibitors N-tosyl-L-phenylalaninechloromethyl ketone (TPCK) and phenyl methyl sulfonyl fluoride (PMSF), showing residual activities of 6% and 0%, respectively. Furthermore, high activity was observed in the pH range of 4.0 to 8.0. Purified enzyme showed a moderate in vitro activity using muscle collagen as a substrate. Although further research is needed, the results suggest that the enzyme has a potential application where acidic or slightly alkaline conditions are needed.

The antimicrobial activity of films made of poly(l-lactic acid)/poly(l-lactic acid) grafted maleic anhydride(copolymer)/epigallocatechin gallate(EGCG) blend was determined. The effect of epigallocatechin gallate incorporation (0.03, 0.5, 5, and 10 wt%) as a natural antibacterial was determined by direct contact, solid and liquid culture media. The film antimicrobial activity was evaluated against two bacteria (gram-negative: Pseudomonas spp.; gram-positive: Staphylococcus aureus). The copolymer was prepared and characterized by Fourier transform infrared analysis and Molau test. Furthermore, the degree of grafting was determined. The epigallocatechin gallate migration profile through the films were determined and the minimum epigallocatechin gallate concentration in films required to show antibacterial activity was evaluated. The results showed that only the films with 10 wt% epigallocatechin gallate significantly affected ( p

Summary Jumbo squid (Dosidicus gigas) is characterised by its low commercial value, lean and white meat without bones or scales and high muscular yield. Therefore, it is an attractive species for the production of protein concentrates. However, the gelling ability of squid proteins is low due to the inherent characteristics of the proteins. Different hydrocolloids can be used to improve the gelling ability, where pH and concentration of the hydrocolloids are very important to stablish. Therefore, this study aimed to obtain a protein concentrate from Dosidicus gigas and evaluate the effect of pH and chitosan concentration on its gelation and conformational changes. Treatment at pH 7.0 with 2% chitosan improved the water-holding capacity, elasticity and agglomeration according to the Z potential; it also improved the thermal stability and gelling according to the dynamic oscillatory measurements and differential scanning calorimetry. This information demonstrates that chitosan incorporation plays an important role in gel formation and improves the gelling capacity of squid proteins without affecting the brightness and whiteness, important parameters for this product.

Different studies on obtaining protein concentrates or surimi from giant squid ( Dosidicus gigas) have reported that soft gels are obtained in comparison with other fish species. Therefore, the aim of this research was to investigate the effect of the setting (30 and 60 °C, for 0, 30, 60, and 90 min) on the gelling capacity as a possible alternative to improve the textural characteristics of the gels. Treatments at 60 °C (G4, G5, and G6) had a higher percentage of insoluble protein, while the electrophoretic profile showed the presence of high molecular weight (HMW) aggregates, as well as the decrease of myosin, paramyosin and actin bands as the incubation time was increased. Likewise, these systems presented a lower content of total sulfhydryl (TSH), which is attributed to the formation of disulfide bridges. The texture profile analysis (TPA) showed that the setting application affected the different parameters evaluated (strength, elasticity, and cohesiveness). Setting as pretreatment did not prove to be a good alternative for the gelling of proteins from giant squid mantle, since the control treatment (no setting) was that which exhibited better textural characteristics.

The products of fishing are highly perishable foods. Thus, it is necessary to seek viable alternatives that help to preserve product freshness and quality and to increase its shelf life. One of these alternatives is the use of extracts with antimicrobial activity obtained from plants, such as tomato, which has been observed to present compounds with antimicrobial activity. The objective of this work was to determine the effect of an extract obtained from the tomato plant and incorporated into an edible chitosan coating on the quality and shelf life of the sierra fish fillet stored on ice for 15 days. For the latter, an extract was prepared with dehydrated tomato plants, which was incorporated by immersion alone or in combination with an edible chitosan-based coating in sierra fish fillets. The following treatments were applied: C (Chitosan), TPE (Tomato Plant Extract), TPE-C (TPE-Chitosan), and control (without chitosan and extract). Color, pH, WHC, ATP-related compounds, and K value were monitored during 15 days of storage on ice. Likewise, the total count of mesophiles was determined. The results indicated that treatments C, TPE, and TPE-C were significantly different (p<0.05) from lot control in terms of the concentration of ATP-related compounds, K value, pH, and total mesophilic count. We concluded that application of the extract alone or in combination with chitosan allows for the improvement of the quality and shelf life of the sierra fish fillet.

Jumbo squid (Dosidicus gigas) is an underutilized fishery resource in the Gulf of California. Jumbo squid muscle could potentially be utilized to manufacture protein concentrates to be used as a base for surimi or as a food ingredient. However, the main problem is the low gelling ability of these protein concentrates compared those of with fish species. Consequently, the present study evaluated the effects of pH and the NaCl concentration on the gelling properties of protein concentrates from squid mantle. According to texture profile analysis, improved gelling properties were obtained at pH 6.0 and 1% of NaCl. During the sol-gel transition, decreased surface hydrophobicity that corresponded to an increased intensity of α-helix structures was detected. Moreover, the total sulfhydryl content decreased during gel formation. Viscoelasticity and water holding capacity analyses showed the formation of a more structured gel at pH 7.0. The higher enthalpy and denaturation temperature detected by differential sca...

Postmortem biochemical and microbiological changes in loricariid catfish (Pterygoplichthys disjunctivus) muscle were evaluated during ice storage for 20 days. Values of pH remained stable for 15 days (7.4 ± 0.2), and total volatile base-nitrogen (TVB-N) remained under acceptable limits throughout storage, with a final value of 25.2 ± 3.3 mg N/100 g muscle at Day 20. Adenosine-5´-triphosphate (ATP) and derivatives followed a postmortem degradation pattern similar to other species, with the K-value being the best freshness loss indicator. Biochemical and microbiological changes indicated that the shelf life of iced loricariid catfish muscle was 15 days under optimal (0°C) storage conditions.

Jumbo squid (Dosidicus gigas) is an important commercialized fishery in Mexico; however, during its post-catch processing, several physicochemical changes occur in flesh, which could result in texture modifications. In this research, changes in water-holding capacity, protein solubility (PS), firmness, fibrils microstructure, and color of squid muscle (mantle, fins, and arms) during cooking (30 min at 100 °C) were evaluated. Throughout cooking were exhibited different shrinkage and weight loss behavior among three anatomical regions (p arms > mantle, whereas at ending cooking, mantle muscle required the lowest SF. Microscopic analysis revealed a major quantity of collagen fibers in fins and arm muscle suggesting its possible relation to their hardness, in both fresh and cooked state. Practical applications Jumbo squid (Dosidicus gigas) is an important marine resource in Mexico and many Asiatic and European countries. Its muscle (fins, arms, and mantle) edible items are commercialized and consumed in fresh, brined, and cooked presentations. Squid muscle protein structures (fibril and stromal) are organized different than fish as well as beef, pork and poultry; therefore its textural, physicochemical and sensorial (quality parameters) changes induced by cooking are distinctive. Squid meat acceptance by consumers is related mainly by texture than the taste or color attributes. Therefore, from economic point of view of domestic and large-scale markets, the establishment of best cooking conditions of squid became essential.

Connective tissue (CT) proteins in jumbo squid (Dosidicus gigas) play an important role because they are the responsible for the union between various cells; hence, there is a close relationship between their functions and muscle firmness during ice storage. In this study, the thermal resistance and solubility of the CT extracted from the fins, mantle and arms of jumbo squid during ice storage (20 days) was evaluated. The CT was fractionated based on solubility [NaCl-soluble (SSCT) and insoluble (ICT)]. The solubility of the CT was affected during ice storage. An increase in the thermal resistance of the SSCT after 10 days with a subsequent decrease was found in the mantle. Furthermore, the ICT was thermally more resistant than the SSCT in all the anatomical regions. Finally, the electrophoretic profile revealed that structural changes occurred, causing changes in its solubility, due to an increase in the thermal resistance. Practical Applications Jumbo squid (Dosidicus gigas) is an important seafood resource in Mexico, which is commercialized primarily iced and fresh-frozen. Its muscle connective tissue (CT) has different physicochemical characteristics that differ from other seafood products; it is thermally more resistant and might be responsible for the textural changes during ice storage. Moreover, specific studies about the behavior of CT proteins in such organism may result in improved post-catch management of jumbo squid muscle, focused on the processing of the species in the food industry or anywhere that CT proteins are used as raw material. The main objective of this research is to investigate solubility changes and thermal resistance of CT proteins of iced jumbo squid mantle.