Microbiological and Sensorial Quality Assessment of Ready-to-Cook Seafood Products Packaged under Modified Atmosphere

ABSTRACT:  The effects of modified atmosphere packaging (MAP) (30:40:30 O₂:CO₂:N₂ and 5:95 O₂:CO₂) on the quality of 4 ready-to-cook seafood products were studied. In particular, the investigation was carried out on hake fillets, yellow gurnard fillets, chub mackerel fillets, and entire eviscerated cuttlefish. Quality assessment was based on microbiological and sensorial indices determination. Both packaging gas mixtures contributed to a considerable slowing down of the microbial and sensorial quality loss of the investigated seafood products. Results showed that sensorial quality was the subindex that limited their shelf life. In fact, based primarily on microbiological results, samples under MAP remained acceptable up to the end of storage (that is, 14 d), regardless of fish specie. On the other hand, results from sensory analyses showed that chub mackerel fillets in MAP were acceptable up to the 6th storage d, whilst hake fillets, yellow gurnard fillets, and entire cuttlefish became unacceptable after 10 to 11 d. However, compared to control samples, an increase in the sensorial shelf life of MAP samples (ranging from about 95% to 250%) was always recorded.
Practical Application: Modified atmosphere packaging (MAP) is an inexpensive and uncomplicated method of extending shelf life of packed seafood. It could gain great attention from the fish industrial sector due to the fact that MAP is a practical and economic technique, realizable by small technical expedients. Moreover, there is great attention from the food industry and retailers to react to the growing demand for convenience food, thus promoting an increase in the assortments of ready-to-cook seafood products.     

Content of mercury and cadmium in fish (Thunnus alalunga) and cephalopods (Eledone moschata) from the south-eastern Mediterranean Sea

Mercury and cadmium concentrations were measured in the flesh and liver (or hepatopancreas) of albacore (Thunnus alalunga) and horned octopus (Eledone moschata) to establish whether the concentrations exceeded the maximum levels fixed by the European Commission. In both species, mercury and cadmium mean concentrations were higher in liver (albacore: mercury = 2.41 μg g^-1 wet wt, cadmium = 9.22 μg g^-1 wet wt; horned octopus: mercury = 0.76 μg g^-1 wet wt, cadmium = 6.72 μg g^-1 wet wt) than in flesh (albacore: mercury = 1.56 μg g^-1 wet wt, cadmium = 0.05 μg g^-1 wet wt; horned octopus: mercury = 0.36 μg g^-1 wet wt, cadmium = 0.33 μg g^-1). Mercury concentrations exceeding the prescribed legal limit of 1 μg g^-1 wet wt were found in almost all albacore samples (flesh: 71.4%; liver: 85.7%). For horned octopus, concentrations above 0.5 μg g^-1 wet wt were observed solely in hepatopancreas, while in flesh, the concentrations were below this limit in all the samples examined. Of the flesh samples of albacore, 42.8% exceeded the proposed tolerance for cadmium for human consumption, whilst for horned octopus, the established limit was not exceeded in any sample.     

Cephalopod-Inspired Stretchable Self-Morphing Skin Via Embedded Printing and Twisted Spiral Artificial Muscles

Cutaneous muscles drive the texture-modulation behavior of cephalopods by protruding several millimeters out of the skin. Inspired by cephalopods, a self-morphing, stretchable smart skin containing embedded-printed electrodes and actuated by Twisted Spiral Artificial Muscles (TSAMs) is proposed. Electrothermally actuated TSAMs are manufactured from inexpensive polymer fibers to mimic the papillae muscles of cephalopods. These spirals can produce strains of nearly 2000% using a voltage of only 0.02 V mm⁻¹. Stretchable and low-resistance liquid metal electrodes are embedded-printed inside the self-morphing skin to facilitate the electrothermal actuation of TSAMs. Theoretical and numerical models are proposed to describe the embedded printing of low-viscosity Newtonian liquid metals as conductive electrodes in a soft elastomeric substrate. Experimental mechanical tests are performed to demonstrate the robustness and electrical stability of the electrodes. Two smart skin prototypes are fabricated to highlight the capabilities of the proposed self-morphing system, including a texture-modulating wearable soft glove and a waterproof skin that emulates the texture-modulation behavior of octopi underwater. The proposed self-morphing stretchable smart skin can find use in a wide range of applications, such as refreshable Braille displays, haptic feedback devices, turbulence tripping, and antifouling devices for underwater vehicles.     

Cadmium content in fresh and canned squid (Loligo opalescens) from the Pacific coastal waters of California (USA)

Cadmium (Cd) levels were determined in 70 samples of mantle tissue and 70 whole individual squid (Loligo opalescens; commercially known as California squid). Samples were collected from the coastal zones of California (USA) during the period 2007/2008. To further investigate consumer exposure to processed fishery products, cadmium concentration was also determined in 200 canned samples of squid. Cd concentrations in raw mantle were low, between 0.01 and 0.29 mg kg^?1 and below the tolerance limit of current regulations (1 mg kg^?1). Respective concentrations in whole individuals were significantly higher, ranging from 0.51 to 1.18 mg kg^?1, attributed to the presence of the visceral portion in whole squid samples. Cd concentrations varied in relation to age and sex of squid, indicating that several physiological factors may influence accumulation. Furthermore, canning of squid substantially enhanced Cd levels. Cd concentration ranged 0.17–0.67 mg kg^?1 in canned mantle tissue and 0.86–2.07 mg kg^?1 in canned whole squid samples, due to both concentration after canning and movement of the metal between different tissues. Several biological compounds, including metallothioneins, nucleic acids and enzymes, may affect Cd concentrations in commercial fishery products.     

Characterization and Functionality of Frozen Muscle Protein in Volador (Illexcoindetii), Pota (Todaropsis eblanae), and Octopus (Eledone cirrhosa)

ABSTRACT: Three species of cephalopods: volador (Illex coindetii) , pota (Todaropsis eblanae) , and octopus (Eledone cirrhosa) were classified according to sex, stage of sexual development, and anatomical zone for characterization and functionality of their muscle proteins. The 3 species exhibited very similar levels of total protein. Octopus mantles and arms contained the least proline and the most hydroxyproline. The highest solubility values in immature pota coincided with the lowest apparent viscosity and emulsifying capacity values. The highest insolubility values observed in octopus coincided with the highest viscosity and emulsifying capacity values. However, in volador which exhibited an intermediate solubility, viscosity was very high and emulsifying capacity was very low.     

Contrasting activity patterns of two related octopus species, Octopus macropus and Octopus vulgaris.

Octopus macropus and Octopus vulgaris have overlapping habitats and are exposed to similar temporal changes. Whereas the former species is described as nocturnal in the field, there are conflicting reports about the activity time of the latter one. To compare activity patterns, the authors tested both species in the laboratory. Octopuses were exposed to a light-dark cycle and held under constant dim light for 7 days each. O. macropus showed nocturnal and light-cued activity. According to casual observations, O. vulgaris started out nocturnal but had switched to mostly diurnal when the experiment began. Individual variation of its activity was found. The different activity patterns of O. macropus and O. vulgaris might reflect their lifestyles, the latter species being more generalist. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Muscle protein solubility of some cephalopods (pota and octopus) during frozen storage

This study relates to myofibrillar and sarcoplasmic protein solubility in 5% NaCl and collagen solubility in 0.05 M acetic acid, from muscle and mantle of pota (Todaropsis eblanae) and octopus (Eledone cirrhosa) kept in frozen storage for 12 months. In both species, protein solubility in 5% NaCl remained high, over 60%, throughout the storage period. Solubility was lower in the octopus than in the pota lots. The species also behaved differently in terms of the increase in solubility, which occurred earlier in octopus (after 2 months) than in pota (after 5–6 months). Thereafter, solubility gradually declined. The values for solubility of proteins from mantle of both pota and octopus in 5% NaCl were greater in young specimens than in mature samples. There was no clear gender‐dependent tendency. The acid solubility of collagen also increased in most lots up to the sixth month, after which it characteristically began to decline. Pota collagen was significantly more soluble in mantles than in arms. In octopus mantle, collagen solubility gradually declined. In the sexually developed phases (immature and mature), no gender‐dependent differences were detected in the solubility of collagen from octopus mantle and arms. However, values did tend to be slightly higher in females. The mantles of immature specimens of pota and octopus were more suitable for freezing. © 2002 Society of Chemical Industry     

Seasonal Survey of Contaminants (Cd and Hg) and Micronutrients (Cu and Zn) in Edible Tissues of Cephalopods from Tunisia: Assessment of Risk and Nutritional Benefits

Concentrations of cadmium (Cd), copper (Cu), mercury (Hg), and zinc (Zn) were determined by atomic absorption spectrophotometry in the muscle tissues (arms and mantle) of 3 commercial cephalopods (Loligo vulgaris, Octopus vulgaris, and Sepia officinalis) caught in 3 different Tunisian coastal regions. The highest concentrations found correspond to the essential elements Cu and Zn. Octopuses and cuttlefish showed the highest levels of those elements whereas squid presented with significantly higher values of Hg in both muscular tissues. This may be related to different feeding behavior and detoxification processes among benthic and pelagic cephalopods. Variation of element concentrations between seasons was different between species and seemed to be mostly dependent on the sampling site. From a public health standpoint, average concentrations of Cd, Cu, Hg, and Zn measured in edible tissues of cephalopods from this study did not reveal, in general, any risk for consumers. The estimated target hazard quotients for Cd and Hg for consumers of the selected species were below 1 and within the safety range for human health. Moreover, their consumption could provide in an important contribution to the daily dietary intake of Cu for the Tunisian population, especially regarding the consumption of octopus and cuttlefish muscles.