Cooked Crab Meat Research Articles

Development of Loop-Mediated Isothermal Amplification (LAMP) Assays for the Rapid Authentication of Three Swimming Crab Species.

Blue swimming crab meat is easily adulterated by other crab meats with a lower price. A potential authentication method is required to prevent mislabeling. LAMP assays were established to identify the meat of blue swimming crab, crucifix crab, and three spotted swimming crab. The primers were designed using PrimerExplorer V5. The specificity of the LAMP assay was tested compared to the PCR method. The sensitivity was conducted at the DNA concentrations of 0.4–50 ng/reaction. The results demonstrated that both LAMP and PCR could discriminate all species of crabs. LAMP showed a superior sensitivity to PCR in the three spotted swimming crab, while a similar result between LAMP and PCR was obtained in blue swimming crab. No changes in the detection efficacy were attained when boiled and steamed crab meats were applied. Therefore, the LAMP assay developed could potentially be applicable to detect the adulteration or mislabeling of raw or cooked crab meat in markets.

Improving of Gelling Capacity of Cooked Crab Meat Proteins.

Cooked crab meat subjected to a cutting process can aggregate again, forming weak gels. The objective of this work was to determine the effect of two mixing methods, combined with the addition of the microbial enzyme TGase (MTGase) on the mechanical and functional properties of gels from washed or unwashed blue crab (Callinectes sapidus) meat. Live crabs were obtained from Laguna Madre, Tamaulipas, Mexico, and cooked at 120°C for 20 min before hand-picking the meat from the shell. Cooked meat was processed by mixing and cut at temperatures of 25 or 60°C, without (control) or 0.5% of MTGase. Then cooked at 90°C for 15 min. Changes in texture profile analysis, percentage of extractable water, and color were evaluated. The mixing method at 60°C allowed increasing the textural properties of the gels, and the addition of MTGase significantly improved the mechanical properties. The results allowed stablishing a viable technique to obtain restructured gels from cooked crab meat with no need to extract the soluble compounds responsible for their distinctive odor and taste which often affect the mechanical properties.

Microbial quality of wild shellfish in a tropical estuary subject to treated effluent discharge

Elevated faecal indicator levels in beaches around Darwin Harbour including near effluent outfalls have led to concerns about the safety of popular, locally harvested aquatic foods. To address these concerns, the impact of treated effluent discharge on the microbial quality of aquatic foods was assessed using culture-based and molecular tools.Seawater, shellfish (mangrove snails Telescopium and Nerita balteata, the local black lip oyster Saccostrea cucullata) and mud crabs (Scylla serrata) were collected from 13 sites close (impacted) and distal (reference) to two effluent discharge locations, in creeks and coastal areas. Sampling occurred over two dry seasons and one wet season.E. coli, typical sewage related pathogens, Salmonella and norovirus, and the molecular faecal marker Bacteroides, as well as naturally occurring marine bacteria, Vibrio parahaemolyticus and Vibrio vulnificus were tested in biota. E. coli and faecal coliforms were measured in water in water.The highest concentration of faecal coliforms in water was from the Buffalo Creek discharge site. At sites located in creeks including reference creeks, the highest concentrations of faecal coliforms in water were measured in the wet season compared to the dry season, whereas in coastal sites, no or only few (<10) faecal coliforms were detected.E. coli concentrations in both snail species were significantly higher in the wet season compared to the dry season (P < 0.0001) at both the treated effluent discharge sites and reference sites with some samples exceeding the acceptable Australian and New Zealand Food Standards (ANZFS) level based on E. coli levels in bivalves.E. coli concentrations in all of the S. cucullata samples were either below the detection limit or below the ANZFS limit for E. coli. No E. coli exceedances occurred in cooked mud crabs although low E. coli levels were measured in 3 cooked mud crab samples.Only one shellfish sample (T. telescopium) was positive for Salmonella. Norovirus and Bacteroides were not detected in any of the shellfish samples tested.V. parahaemolyticus and V. vulnificus were significantly more prevalent in shellfish samples during the wet season. Twelve virulent strains of V. parahaemolyticus were detected in T. telescopium and two in N. balteata. There was no significant difference in V. parahaemolyticus prevalence between sites. V. parahaemolyticus was detected in cooked S. serrata samples from three sites in the wet season and once in the 2016 dry season.V. vulnificus was detected in both T. telescopium and N. balteata, but not in any of the S. cucullata samples. One cooked crab meat sample from a reference site was positive for V. vulnificus. The prevalence of V. vulnificus was significantly higher at the reference sites compared to the discharge or potential impact sites.The lack of correlation between E. coli and targeted faecal pathogens in biota confirm that traditional faecal markers are not suitable surrogates for faecal pollution, at least not in the tropics.The higher prevalence of E. coli, V. parahaemolyticus and V. vulnificus in biota during the wet season compared to the dry season irrespective of treated sewage influence suggests that marine snails should not be harvested and consumed from creeks during the wet season. Any future aquaculture involving shellfish should consider these data when developing appropriate shellfish quality assurance protocols and for making decisions on where to situate farms.

Prevalence, characterization and sources of Listeria monocytogenes in blue crab (Callinectus sapidus) meat and blue crab processing plants

Seven blue crab processing plants were sampled to determine the prevalence and sources of Listeria spp. and Listeria monocytogenes for two years (2006–2007). A total of 488 raw crabs, 624 cooked crab meat (crab meat) and 624 environmental samples were tested by standard methods. Presumptive Listeria spp. were isolated from 19.5% of raw crabs, 10.8% of crab meat, and 69.5% of environmental samples. L. monocytogenes was isolated from 4.5% of raw crabs, 0.2% of crab meat, and 2.1% of environmental samples. Ninety-seven percent of the isolates were resistant to at least one of the ten antibiotics tested. Eight different serotypes were found among 76 L. monocytogenes isolates tested with the most common being 4b, 1/2b and 1/2a. Automated EcoRI ribotyping differentiated 11 ribotypes among the 106 L. monocytogenes isolates. Based on ribotyping analysis, the distribution of the ribotypes in each processing plant had a unique contamination pattern. A total of 92 ApaI and 88 AscI pulsotypes among the 106 L. monocytogenes isolates were found and distinct pulsotypes were observed in raw crab, crab meat and environmental samples. Ribotypes and serotypes recovered from crab processing plants included subtypes that have been associated with listeriosis cases in other food outbreaks. Our findings suggest that molecular methods may provide critical information about sources of L. monocytogenes in crab processing plants and will augment efforts to improve food safety control strategies such as targeting specific sources of contamination and use of aggressive detergents prior to sanitizing.

Gelation properties of previously cooked minced meat from Jonah crab (Cancer borealis) as affected by washing treatment and salt concentration

The influence of washing treatment (dewatered only, one wash, and three washes) and sodium chloride (NaCl) concentration (0%, 2%, and 4%) on the gelation properties of crab mince was investigated. This previously cooked muscle mince is a low-value by-product of the crab processing industry, considered to have little or no functional properties. Crab mince gels were produced and tested for water-holding capacity (WHC), gel strength, colour, and electrophoretic profile. Wash treatment and NaCl concentration significantly affected gelation. Washed samples exhibited significantly higher WHC than dewatered samples. The 4% NaCl treatment decreased WHC compared to lower NaCl levels. Multiple washing steps increased the force to gel deformation. Wash treatment and NaCl concentration also affected the colour of gels. Based on these results, cooked crab meat mince treated with three washes and 0% NaCl resulted in the strongest gels with the best water-holding capacity, which can be used in the development of value-added products.

Thermal Gelation of Previously Cooked Minced Meat from Jonah Crab (Cancer borealis)

ABSTRACT: Crab processing typically involves picking meat from whole cooked product. Remaining meat can be recovered as mince and potentially processed into value‐added products. This study focused on gelation of commercially processed crab mince. Objectives of the research were to determine the effects of cryoprotectants, freezing, and various heat treatments on gel formation of washed mince from previously cooked crab. Previously frozen minced meat from thermally processed Jonah crab was washed to remove soluble components. Four different treatments were applied to the washed mince: (1) freezing with cryoprotectants, (2) freezing with no cryoprotectants, (3) no freezing with cryoprotectants, and (4) no freezing with no cryoprotectants. Unwashed mince was used as a control treatment. Sodium chloride (2.5%) was mixed into the mince prior to stuffing into sausage casings and heating at 35 °C/30 min, 90 °C/30 min, or 35 °C/30 min followed by 90 °C/30 min. Gels were tested for proximate composition, color, water‐holding capacity, and gel strength. All mince samples formed gels except for the unwashed control. Gels with no cryoprotectants had 10% to 20% greater water holding capacity, lower L* values, and greater gel strength than those with cryoprotectants. Freezing of washed mince resulted in lower water‐holding capacity of gels and higher a* values. A 2‐stage heating treatment resulted in gels with the greatest gel strength, whereas gels cooked at 35 °C had the greatest distance to fracture. Results indicate that protein gels can be formed using previously cooked crab meat, which may be useful in the development of value‐added products.

Liquid Chromatography/Tandem Mass Spectrometry Analysis of Chloramphenicol in Cooked Crab Meat

A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method is described for the extraction, cleanup, determination, and confirmation of chloramphenicol (CAP) in cooked crab meat. The method involves pulverization of cooked crab meat with dry ice; extraction of the CAP into ethyl acetate (EtOAc); evaporation (by N2) of the EtOAc; addition of methanol, aqueous NaCl, and heptane; extraction of the lipids into the heptane, followed by extraction of the aqueous phase with EtOAc; evaporation (by N2) of the EtOAc; dissolution into methanol-water; filtration; and separation/detection/confirmation using LC/MS/MS. Crab meat was fortified at 0.25, 0.50, and 1.0 ng/g (ppb) chloramphenicol. Average absolute recoveries were 67, 84, and 86%, respectively, with relative standard deviation values all less than 1%. Four daughter ions (m/z 152, 176, 194, and 257) were monitored off the m/z 321 precursor ion. Determination was based on a standard curve using the peak areas of the m/z 152 daughter ion (the base peak) for standard solutions equivalent to 0.10, 0.20, 0.50, and 1.0 ppb in tissue (made with control crab extract). A set of 6 matrix controls (unfortified crab meat) was also analyzed, in which no chloramphenicol was detected. For identification purposes, the ion ratios (of each daughter ion versus the base daughter ion) of the fortified crab versus those of the chloramphenicol standards agreed within 10% (relative) at fortified chloramphenicol concentrations of 0.25-1.0 ppb.

Proximate and mineral composition of crab meat consumed in Bahrain

The proximate, mineral and heavy metals of raw and cooked crab meat, Portunus pelagicus, consumed in Bahrain were studied. The crab meat contains a good level of protein (17.5–18.8%), with very low proportion of fat (0.6–1.4%). The levels of sodium, potassium, calcium and phosphorus were found to be higher than other minerals. Traces of heavy metals (lead, mercury, cadmium) were also reported. Traditional cooking had a considerable effect on proximate and mineral contents of crab meat.

Identification of raw and cooked snow crab proteins that elicit IgE reactivity in snow crab processing workers

Rationale Snow crab proteins produce IgE-mediated reactions in crab processing workers. We sought to identify and compare the relevant allergenic proteins in raw crab (RC) and cooked crab (CC). Methods Sera were selected based on IgE reactivity to RC (8), CC (3), or both (3). RC and CC meat proteins were separated by SDS-PAGE electrophoresis, transferred to nitrocellulose membranes incubated with the IgE-reactive sera and then 125I-anti-IgE. IgE-reactive proteins were detected by autoradiography. Competitive immunoassay using RC or CC inhibitors ranging from 500μg to 0.001μg concentrations was performed to compare RC and CC allergens. Results RC and CC-reactive sera detected three proteins in RC and CC (14.4 kD, 18.5 kD, and 25.1 kD proteins). There were 5 additional reactive proteins identified only in RC (including 28.2 kD, 34 kD, and 40.7 kD proteins), and several proteins (14.4 kD to 54.3 kD) identified only in CC. IgE inhibition revealed that 10 μg of RC inhibited RC sera pool 76%; whereas 10 μg of CC did not inhibit RC sera pool significantly (8%). Similarly, 1μg of CC inhibited CC sera pool 86%, whereas 1μg of RC only inhibited CC sera pool 44%. Conclusions Three IgE-reactive proteins were common to RC and CC. Five other IgE-reactive proteins identified in RC were not present in CC. IgE inhibition results demonstrate a difference in the allergenic content of RC and CC. Additional studies will further identify allergens in RC and CC and determine their role in occupational allergy of crab workers.

Evaluation of the Listertest™ Method for Quantitation of Listeria monocytogenes in Seafoods

The U.S. Food and Drug Administration most probable number (MPN) method and the Listertest™ (immunomagnetic capture) were used to enumerate Listeria monocytogenes on laboratory-inoculated cooked crabmeat (Callinectus sapidus) and cold-smoked salmon (Salmo salar). The products were inoculated with <1.0 to 4.0 log CFU of L. monocytogenes per g and analyzed immediately. In the analyses of crabmeat, the results obtained by the MPN method were significantly lower (P < 0.05) than counts produced by the Listertest™. There was no significant difference (P < 0.05) between results produced by MPN and the Listertest™ in analyses of smoked salmon. The methods had the same variance in the quantitation of L. monocytogenes in these seafood products.

Comparative Growth Rates of Salmonella typhimurium and Pseudomonas fragi on Cooked Crab Meat Stored Under Air and Modified Atmosphere

Crab meat packaged in plastic (polypropylene, Fisher) jars was sterilized, cooled, and inoculated with approximately 103 cells/g each of Salmonella typhimurium and Pseudomonas fragi. Inoculated samples were packaged either under air or a commercial modified atmosphere (MA) gas mix containing 50% CO2/10% O2/balance proprietary. These samples were stored at 7 and 11°C. At 0, 2, 4, and 6 d after inoculation, three samples per treatment at each temperature were tested for populations of inoculum species. S. typhimurium did not grow under either atmosphere at 7°C but grew under air and MA at 11 °C. MA-storage slowed the growth of both S. typhimurium and P. fragi at 11°C, although growth of S. typhimurium was more severely inhibited. Use of 50% CO2/10% O2/balance proprietary MA-storage may greatly extend the shelf life of crab meat, but in the absence of proper refrigeration, it cannot be relied upon to eliminate the risk of salmonellosis.

Presence, Growth and Survival of Yersinia enterocolitica in Oysters, Shrimp and Crab

Yersinia enterocolitica was recovered from 6 of 45 (13%) oyster, 2 of 50 (4%) shrimp and 12 of 58 (21%) blue crab samples. No single method of enrichment (cold mannitol broth or modified Rappaport broth for 7, 21 or 60 days) was most effective for the three types of shellfish examined. The effect of refrigerated storage on Y. enterocolitica depended upon the type of shellfish, condition (raw or boiled), strain of Y. enterocolitica and temperature and time of storage. In general, Y. enterocolitica counts increased in (a) raw oysters stored at 0–2 C for 14–21 days and at 5–7 C for 2–10 days, (b) in boiled shrimp stored at 3–5 C for 7–21 days and (c) in cooked crab meat stored at 5 C for 14 days. Freezing and heating of shrimp and crab meat caused extensive destruction of Y. enterocolitica. Biotypes capable of causing human illness (when inoculated into seafoods) survived and under certain conditions multiplied at refrigeration temperatures. Biochemical characteristics of the isolates from raw shellfish differed from those of clinically significant types.

Identification of Species in Cooked Crabmeat by Thin Layer Isoelectric Focusing

Thin layer polyacrylamide gel isoelectric focusing (TLIEF) is described for characterizing the species-specific, heat-denatured proteins of 8 species of crab: red (Geryon quinquedens), rock (Cancer irroratus), Jonah (Cancer borealis), blue (Callinectes sapidus), king (Paralithodes camtschatica), snow (Chionoectes spp.), European edible (Cancer pagurus), and dungeness (Cancer magister). Protein pattern differences are shown not only among species, but also between 2 modes of heat processing of the crabmeat. Individual variation within the species as to sex, size and maturity, length of frozen storage, and body parts chosen for sampling do not alter the species banding pattern. The reproducible species-specific fingerprint obviates the need to analyze authenticated samples simultaneously with the unknown crabmeat.

DEGRADATION OF ADENINE NUCLEOTIDES IN THE MUSCLE OF THE DUNGENESS CRAB (CANCER MAGISTER) AND KING CRAB (PARALITHODES CAMTSCHATICA) DURING STORAGE AND COOKING

The adenine nucleotide content of king and Dungeness crab was determined on muscle before and after storage and on heat-processed or cooked crab meat. As a result of both storage and heat processing, adenosine triphosphate (ATP) and adenosine diphosphate (ADP) are degraded to adenosine monophosphate (AMP) and inosine and hypoxanthine. Only small amounts of inosine monophosphate (IMP) are found in cooked crabmeat. Flavor evaluation of IMP-treated king crab showed that IMP plays only a minor role in the flavor of crab.