Cooked Shrimp Research Articles

Stability of Major Shrimp Allergens in a Food Manufacturing Facility for Drug Delivery

Understanding the stability of the shrimp allergen tropomyosin (TM) in shrimp powder at different temperatures is necessary to develop shrimp oral immunotherapy (SOIT). We evaluated the shrimp TM stability for different storage times for utilization in a SOIT clinical trial and determined the specific IgE (sIgE) binding capacity of raw and cooked shrimp allergen extracts.

Genetic parameters of color phenotypes of black tiger shrimp (Penaeus monodon).

Black tiger shrimp (Penaeus monodon) is the second most important aquaculture species of shrimp in the world. In addition to growth traits, uncooked and cooked body color of shrimp are traits of significance for profitability and consumer acceptance. This study investigated for the first time, the phenotypic and genetic variances and relationships for body weight and body color traits, obtained from image analyses of 838 shrimp, representing the progeny from 55 sires and 52 dams. The color of uncooked shrimp was subjectively scored on a scale from 1 to 4, with “1” being the lightest/pale color and “4” being the darkest color. For cooked shrimp color, shrimp were graded firstly by subjective scoring using a commercial grading score card, where the score ranged from 1 to 12 representing light to deep coloration which was subsequently found to not be sufficiently reliable with poor repeatability of measurement (r = 0.68–0.78) Therefore, all images of cooked color were regraded on a three-point scale from brightest and lightest colored cooked shrimp, to darkest and most color-intense, with a high repeatability (r = 0.80–0.92). Objective color of both cooked and uncooked color was obtained by measurement of RGB intensities (values range from 0 to 255) for each pixel from each shrimp. Using the “convertColor” function in “R”, the RGB values were converted to L*a*b* (CIE Lab) systems of color properties. This system of color space was established in 1976, by the International Commission of Illumination (CIE) where “L*” represents the measure of degree of lightness, values range from 0 to 100, where 0 = pure black and 100 = pure white. The value “a*” represents red to green coloration, where a positive value represents the color progression towards red and a negative value towards green. The value “b*” represents blue to yellow coloration, where a positive value refers to more yellowish and negative towards the blue coloration. In total, eight color-related traits were investigated. An ordinal mixed (threshold) model was adopted for manually (subjectively) scored color phenotypes, whereas all other traits were analyzed by linear mixed models using ASReml software to derive variance components and estimated breeding values (EBVs). Moderate to low heritability estimates (0.05–0.35) were obtained for body color traits. For subjectively scored cooked and uncooked color, EBV-based selection would result in substantial genetic improvement in these traits. The genetic correlations among cooked, uncooked and body weight traits were high and ranged from −0.88 to 0.81. These suggest for the first time that 1) cooked color can be improved indirectly by genetic selection based on color of uncooked/live shrimp, and 2) intensity of coloration is positively correlated with body weight traits and hence selection for body weight will also improve color traits in this population.

Effect of household culinary processes on organochlorine pesticide residues (OCPs) in the seafood (Penaeus vannamei) and its associated human health risk assessment: Our vision and future scope

Food safety is crucial in today's competitive trading market, as it directly affects human health and promotes seafood exports. The effects of thermal processing (boiling, frying, grilling, and microwave cooking) on pesticide residues (PR) in P. vannamei were assessed. The PR in raw and processed shrimp ranged from 0.007 to 0.703 μg/kg for uncooked/raw, not detected (ND) to 0.917 μg/kg for boiled, ND to 0.506 μg/kg for fried, ND to 0.573 μg/kg for grilled and ND to 0.514 μg/kg for microwave cooked shrimps. The Endrin, endosulfan sulfate, and heptachlor were predominant PR found in the raw and processed shrimp. The PR content in raw and cooked shrimps were below the maximum residue limits (MRL) set by the Codex Alimentarius Commission (2021) and the European Commission (86/363/1986 and 57/2007). The estimated daily intake (EDI) of PR from raw and processed shrimps were below the ADI prescribed by CAC. The hazard quotient (HQ) and hazard ratio (HR) values were <1, indicating no non-carcinogenic or carcinogenic health implications through shrimp consumption. The estimated maximum allowable shrimp consumption rate (CRlim) suggests an adult can eat >100 shrimp meals/month, which is over the USEPA's (2000)recommendation of >16 meals/month without health issues. The Effect of thermal processing was detected in the following order: boiling < grilling < frying < microwave cooking. The processing factor (PF < 0.7), paired t-test (t < 0.05), Tukey post hoc (p < 0.05) test, Bray-Curtis similarity index, and matrix plot exhibited that all the four thermal processing methods have a considerable impact on pesticides in the processed shrimps. But frying (59.4%) and microwave cooking (60.3%) reduced PR far beyond boiling (48.8%) and grilling (51.3%). Hence, we recommend frying and microwave processing are better methods for minimizing PR in seafood than boiling or grilling.

Insight into IgG/IgE binding ability, in vitro digestibility and structural changes of shrimp (Litopenaeus vannamei) soluble extracts with thermal processing

The effects of six kinds of thermal processing on soluble protein recovery, potential allergenicity, in vitro digestibility and structural characteristics of shrimp soluble proteins were evaluated. Obtained results confirmed soluble protein recovery and IgG/IgE reactivity of shrimp soluble extracts were markedly suppressed by various thermal treatments with enhanced digestibility depended on the extent and type of heating applied, which correlated well with the structural alterations and modification. The maximum reduction of IgG/IgE-binding capacity and digestive stability were observed in the autoclaved shrimps because of unfolding of protein and hydrophobic residues exposed. Notably, tropomyosin (TM) and sarcoplasmic calcium-binding protein (SCP) were still IgG/IgE-reactive in various heat-processed shrimps, even higher IgG reactivity were found in heat-treated shrimps TM according to TM antiserum western-blotting and indirect ELISA results. Shrimp TM and SCP maintains its IgE/IgG-binding capacity after various cooking methods, thus most probably initiating allergic sensitization to both raw and cooked shrimps.

Effect of different thermal processing methods on potentially toxic metals in the seafood, Penaeus vannamei, and the related human health risk assessment

The presence of a significant amount of toxic metal in seafood has raised human health concerns worldwide. This study investigates the effect of heat processing/cooking methods (boiling, frying, grilling, and microwave cooking) on toxic metals concentration in farmed shrimp and estimates its potential human health risks. Pacific white leg shrimps (Penaeus vannamei) farmed along the Gulf of Mannar region were used to evaluate the toxic metal uptake by consuming raw and cooked shrimps. Toxic heavy metals such as Cd, Hg, and Pb were found below the maximum residual limit (MRL) of 0.5 mg/kg set by the European Union. The concentration of Cu, Zn, and As were below the MRLs of 30 mg/kg, 100 mg/kg, and 76 mg/kg set by the World Health Organization and Food Safety and Standard Authority of India, respectively. The target hazard quotient (THQ) for individual metals and total THQ (TTHQ) for combined metals were <1, indicating no health risk for shrimp consumers. The lifetime cancer risk (LCR) for toxic heavy metals (Cr, Ni, As, Sr, Cd, and Pb) were found between the recommended level of 10−6 to 10-4, indicating no carcinogenic health consequences. With the estimated maximum allowable consumption rates (CRmm), an adult can safely consume >30 raw or cooked shrimp meals/month with no adverse health consequences. Therefore, culinary processes such as boiling and grilling are recommended as suitable methods to reduce toxic metals risk. However, it is recommended to monitor their concentration before and after cooking shrimps collected worldwide and ensure they are within the regulatory limits.

Zootechnical performance, biochemical response, and chromaticity in Pacific white shrimp (Litopenaeus vannamei) (Boone, 1931) after the inclusion of lyophilized açaí (Euterpe oleracea) in the diet

Functional foods have molecules that promote health benefits beyond their nutritional qualities. In this context, the zootechnical performance, color, and biochemical responses of Pacific white shrimp (Litopenaeus vannamei) fed with different levels of acai (Euterpe oleracea), a fruit with unique antioxidant characteristics, were observed. Four diets with different levels of inclusion of lyophilized acai (0.0%, 2.5%, 5.0%, and 10.0% W/W) were administered to shrimps reared in biofloc technology (BFT) systems. After 43 days, the zootechnical parameters (weight gain, feed conversion ratio, and specific growth rate) and coloration in fresh and cooked shrimps were measured, and the L*, a*, and b* parameters were estimated with a digital colorimeter. Survival and growth performances were not affected by acai inclusion in diets. Acai inclusion modulates the flavonoid content in the gills of L. vannamei and in the bioflocs of the rearing BFT system. As in the diet of 10.0% acai, performed with a total replacement of fish oil without affecting growth, we propose the use of acai as a vegetal oil source for shrimp feeding in BFT systems. Acai also induced the reddish color in fresh and cooked L. vannamei, an influential factor in their commercial value.

Romer Labs RapidChek®Listeria monocytogenes Test System for the Detection of L. monocytogenes on Selected Foods and Environmental Surfaces.

The Romer Labs RapidChek® Listeria monocytogenes test system (Performance Tested Method 011805) was validated against the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook (USDA-FSIS/MLG), U.S. Food and Drug Association Bacteriological Analytical Manual (FDA/BAM), and AOAC Official Methods of Analysis (AOAC/OMA) cultural reference methods for the detection of L. monocytogenes on selected foods including hot dogs, frozen cooked breaded chicken, frozen cooked shrimp, cured ham, and ice cream, and environmental surfaces including stainless steel and plastic in an unpaired study design. The RapidChek method uses a proprietary enrichment media system, a 44-48h enrichment at 30 ± 1°C, and detects L. monocytogenes on an immunochromatographic lateral flow device within 10min. Different L. monocytogenes strains were used to spike each of the matrixes. Samples were confirmed based on the reference method confirmations and an alternate confirmation method. A total of 140 low-level spiked samples were tested by the RapidChek method after enrichment for 44-48h in parallel with the cultural reference method. There were 88 RapidChek presumptive positives. One of the presumptive positives was not confirmed culturally. Additionally, one of the culturally confirmed samples did not exhibit a presumptive positive. No difference between the alternate confirmation method and reference confirmation method was observed. The respective cultural reference methods (USDA-FSIS/MLG, FDA/BAM, and AOAC/OMA) produced a total of 63 confirmed positive results. Nonspiked samples from all foods were reported as negative for L. monocytogenes by all methods. Probability of detection analysis demonstrated no significant differences in the number of positive samples detected by the RapidChek method and the respective cultural reference method.

Reduction of the Phosphate Soaking Time Required for Shrimp Products Using Pulsed Vacuum Condition

ABSTRACTPulsed vacuum (PV) was used to reduce the phosphate soaking time for raw and cooked shrimp, without reducing its quality. The shrimp was soaked in a phosphate solution under cycles of vacuum pressure (15 kPa, 7 min) and atmospheric (ATM) pressure (101 kPa, 3 min). PV-soaked shrimp reached stable absorption faster than ATM-soaked shrimp. At equilibrium absorption, no differences in moisture or phosphate contents were observed between PV- and ATM-soaked shrimp. After cooking, PV-soaked and ATM-soaked shrimp showed no differences in product yield or texture. Therefore, PV soaking reduces soaking time but does not affect the yield of cooked shrimp, increasing production capacity. Moreover, this study suggests that to maximize the yield of raw-soaked shrimp, shrimp should be soaked until the moisture content reaches equilibrium. In contrast, cooked shrimp should be soaked until the phosphate content stabilizes, to produce the highest yield with the lowest soaking time.

Reduction of infection risk mediated by co-culturing Vibrio parahaemolyticus and Listeria monocytogenes in refrigerated cooked shrimp.

Vibrio parahaemolyticus and Listeria monocytogenes are seafood pathogens of public health significance, and predictive models are effective tools for quantitative microbial risk assessment of these pathogens. However, most current predictive models are based on growth of single strains in broth cultures, and interactions of two or more bacteria in a food matrix can skew the outcomes of the predictions. Therefore, the impact of V. parahaemolyticus and L. monocytogenes when co-cultured and in monoculture on cooked shrimp in cold storage was investigated. The results indicated that L. monocytogenes co-cultured with V. parahaemolyticus exhibited reduced growth and longer lag phase at 4 °C and 10 °C. V. parahaemolyticus exhibited similar behavior when co-cultured with L. monocytogenes at 4 °C (death rate K=-0.67 log10 CFU g-1 day . The death rate K at 10 °C when V. parahaemolyticus co-cultured with L. monocytogenes was -1.62 log10 CFU g-1 day-1 . There was no significant reduction of growth in monoculture experiments. This study has revealed that interaction of V. parahaemolyticus and L. monocytogenes should be considered when quantifying risks posed by these pathogens during consumption of seafood products. © 2018 Society of Chemical Industry.

In Vitro Model To Assess Arsenic Bioaccessibility and Speciation in Cooked Shrimp.

Shrimp, a popular and readily consumed seafood, contains high concentrations of arsenic. However, few studies have focused on whether arsenic in the shrimp could be transformed during the cooking process and gastrointestinal digestion. In this study, a combined in vitro model [Unified Bioaccessibility Research Group of Europe (BARGE) Method-Simulator of Human Intestinal Microbial Ecosystem (UBM-SHIME)] was used to investigate arsenic bioaccessibility and its speciation in raw and cooked shrimps. The results showed that the cooking practices had little effect on the arsenic content and speciation. Bioaccessibility of arsenic in raw shrimp was at a high level, averaging 76.9 ± 4.28 and 86.7 ± 3.74% in gastric and small intestinal phases, respectively. Arsenic speciation was stable in all of the shrimp digestions, with nontoxic arsenobetaine (AsB) being the dominated speciation. The cooking practice significantly increased the bioaccessibility of arsenate ( p < 0.05) in shrimp digests, indicating the increase of the potential health risks.

Effect of Protein-Based Edible Coating from Red Snapper (Lutjanus sp.) Surimi on Cooked Shrimp

Surimi can be used as a raw material for making protein based edible coating to protect cooked shrimp color. The purpose of this study was to determine consumers preference level on cooked shrimp which coated by surimi edible coating from red snapper and to know the microscopic visualization of edible coating layer on cooked shrimp. The treatments for surimi edible coating were without and added by sappan wood (Caesalpinia sappan Linn) extract. Application of surimi edible coating on cooked shrimp was comprised methods (1) boiled then coated and (2) coated then boiled. Edible coating made from surimi with various concentrations which were 2, 6, 10 and 14% of distillated water. The analysis were done using hedonic test and microscopic observation with microscope photographs. Effect of surimi edible coating on cooked shrimp based on the hedonic and colour test results showed that the 14% surimi concentration, added by sappan wood (Caesalpinia sappan Linn) extract on edible coating was the most preferable by panellist and giving the highest shrimp colour. The edible coating surimi application on cooked shrimp which gave the best result was processed by boiling followed by coating.

Detecting Allergens From Black Tiger Shrimp Penaeus monodon That Can Bind and Cross-link IgE by ELISA, Western Blot, and a Humanized Rat Basophilic Leukemia Reporter Cell Line RS-ATL8.

BackgroundBlack tiger shrimp Penaeus monodon is one of the common causes of shellfish allergy that is increasing worldwide. One of the important problems in the management of shellfish allergy is the lack of accurate diagnostic assay because the biological and immunological properties of allergens in black tiger shrimp have not been well characterized. This study aims to detect proteins with the ability to bind and cross-link immunoglobulin E (IgE) from black tiger shrimp by enzyme-linked immunosorbent assay (ELISA), Western blot, and a humanized rat basophilic leukemia reporter cell line RS-ATL8.MethodsSera from shrimp allergic subjects were subjected to ELISA and Western blots using raw or cooked shrimp extract as antigens. Pooled sera were used to sensitize the RS-ATL8 reporter cell line and cells were activated by shrimp extract. Eluted protein extracts separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were tested on the RS-ATL8 cell line and subjected to mass spectrometry to identify potential candidate allergens.ResultsAllergic sera reacted stronger to raw shrimp extract than cooked shrimp extract (P=0.009). Western blot demonstrated that major IgE reactivity protein bands were at 32–39 kDa and 91–230 kDa in both raw and cooked shrimp extracts. The eluted protein bands at the molecular weight of 38 and 115 kDa from raw shrimp extract induced IgE cross-linking as assayed by the RS-ATL8 cell line. These protein bands were subjected to mass spectrometry for analysis. Ubiquitin-activating enzyme and crustacyanin were identified as potential candidate novel shrimp allergens.ConclusionsThe RS-ATL8 reporter cell line can be used to identify potential new shrimp allergens that can functionally cross-link IgE and induce mast cell degranulation.

The intelligent control strategy of frozen cooked shrimp production process and energy step utilisation

By the investigation of the frozen cooked shrimp production process in Zhanjiang area of Guangdong, China, it is found that Most of the production of frozen cooked shrimp production process control strategy will not be considered. Therefore, some individual processing sometimes may be caused repeat. Product quality would be affected and increase the processing energy use. Intelligent control of frozen cooked shrimp processing strategy as processing instructions, the quality of frozen cooked shrimp would be better, more conducive to energy saving, water saving and improve the production processing environment.

Comparative study on properties of chitosan from raw and cooked shrimp shell and the use as clarifying agent in apple juice

Comparative study on properties of chitosan from raw and cooked shrimp shell and the use as clarifying agent in apple juice

Potential of thermoluminescence analysis over electron paramagnetic resonance approach to identify irradiated shrimp even after cooking

Thermoluminescence (TL) technique and Electron Paramagnetic Resonance (EPR) spectroscopy were employed to identify irradiated Indian shrimp after prolonged storage of 65 days and cooking at maximum temperature of 120°C. The composition of isolated minerals from intestinal grits revealed the origin of thermoluminescence. The TL glows of irradiated samples were characterized by a peak at around 220°C. Radiation-induced TL signal was detected even after cooking at 120°C. In case of EPR spectroscopy outer shell of the shrimp was chosen to study paramagnetic species. An anisotropic radiation induced paramagnetic center was found and characterized by g⊥ = 2.0046 and g|| = 1.997 for the shrimps exposed to 8 kGy. However, radiation-specific EPR signal disappeared after cooking and was not able to help detect irradiation below 3–4 kGy. The results of this study suggested potential of TL technique in identification of irradiated and cooked shrimp exposed to commercially relevant radiation doses. Practical applications Radiation processing is one of the important food preservation technologies. Preservation by ionizing radiation can play an important role in hygienization of shrimps, thereby, contributing toward export of sea-foods. Identification of irradiated food is of paramount importance to consumer, facility operators, and regulators. However, detection of negligible changes in irradiated food matrix is a challenging task. The present study explains the potential of two independent approaches based on thermoluminescence (TL) and electron paramagnetic resonance (EPR) spectroscopy in detection of irradiated shrimp. Further, TL technique exhibited potential to identify irradiated shrimp even after cooking. The results obtained could be of immense help toward all the stakeholders associated with this technology in consumer acceptance, and decision making.

A Novel Functional Wrapping Design by Complexation of ε-Polylysine with Liposomes Entrapping Bioactive Peptides

An innovative edible wrapping with potential use for designing functional foods with antimicrobial capacity was developed by complexation of e-polylysine with peptide-loaded liposomes. Unmarketable long-term frozen cooked shrimp (Litopenaeus vannamei) muscle was used as a source of both bioactive peptides and complex liposomal suspension carrier, producing a sustainable value-added protein wrapping material with desirable sensory properties. A <10-kDa peptide fraction (SH) with antioxidant and angiotensin-converting enzyme inhibitory capacity was encapsulated in partially purified phosphatidylcholine (PC) liposomes (LSH) with an entrapment efficiency of 85 %. The average size and zeta potential of LSH were 164 ± 2 nm and –37.0 ± 1.7 mV, respectively. The LSH surface changed from electronegative to electropositive upon adsorption of e-polylysine (PL) with an optimal concentration of 0.5 %. The average diameter and zeta potential of the resulting complex e-polylysine-adsorbed liposomes containing the peptide hydrolysate (PL-LSH) were 216 ± 5 nm and +51.1 ± 1.1 mV, respectively. The e-PL proved to be effective as liposome stabilizing and antimicrobial agent. The PL-LSH suspension was incorporated in the formulation of the protein wrapping to provide it with both bioactive and antimicrobial properties. The wrapping showed low water solubility (≈30 %) and low mechanical resistance (tensile strength = 0.23 ± 0.06 MPa; elongation at break = 0.91 ± 0.19 %) properties that allowed it to be very versatile for varied food design and was effective against Listeria monocytogenes, Escherichia coli, Staphylococcus aureus and Yersinia enterocolitica.

An investigation on the application of ohmic heating of cold water shrimp and brine mixtures

Cooking is an important unit-operation in the production of cooked and peeled shrimps. The present study explores the feasibility of using ohmic heating for cooking of shrimps. The focus is on investigating the effects of different process parameters on heating time and quality of ohmic cooked shrimps (Pandalus Borelias). The shrimps were heated to a core temperature of 72 °C in a brine solution using a small batch ohmic heater. Three experiments were performed: 1) a comparative analyses of the temperature development between different sizes of shrimps and thickness (head and tail region of the shrimp) over varying salt concentrations (10 kg m−3 to 20 kg m−3) and electric field strengths (1150 V m−1 to 1725 V m−1) with the heating time as the response; 2) a 2 level factorial experiment for screening the impact of processing conditions using electric field strengths of 1250 V m−1 and 1580 V m−1 and salt concentrations of 13.75 kg m−3 and 25.75 kg m−3 and 3) evaluating the effect of pretreatment (maturation) of the shrimps before ohmic processing. The maturation experiment was performed with the following maturation pre-treatments: normal tap water, a 21.25 kg m−3 brine solution and without maturation. The measured responses for experiments 2 and 3 were: the heating time until the set temperature of the shrimps was reached, weight loss, press juice and texture profile. It was possible to fit main effects model relating process settings and the heating time, weight loss and press juice measurements. Furthermore, the results showed that over the tested process workspace no significant changes were seen in the texture measurements of the shrimps and that the shrimp achieved a comparable quality compared to the conventional heating processes reported in the literature. The findings show a promising utilization of ohmic heating as a unit operation for the shrimp processing industries.

Prediction of spoilage of tropical shrimp (Penaeus notialis) under dynamic temperature regimes

The spoilage activity of Pseudomonas psychrophila and Carnobacterium maltaromaticum, two tropical shrimp (Penaeus notialis) spoilage organisms, was assessed in cooked shrimps stored at 0 to 28°C. Microbiological, chemical and sensory analyses were performed during storage. P. psychrophila had a higher growth rate and showed a higher spoilage activity at temperatures from 0 to 15°C, while at 28°C, C. maltaromaticum had a higher growth rate. The spoilage activity of P. psychrophila was found to be higher in cooked shrimp than in fresh shrimp. Observed shelf-life data of shrimps stored at constant temperatures were used to validate a previously developed model that predicts tropical shrimp shelf-life at constant storage temperatures. Models predicting the growth of the spoilage organisms as a function of temperature were constructed. The validation of these models under dynamic storage temperatures simulating temperature fluctuation in the shrimp supply chain showed that they can be used to predict the shelf-life of cooked and fresh tropical shrimps.

Validation of real-time PCR for detection of six major pathogens in seafood products

Abstract Seafood can pose a public health concern to consumers. It is often consumed raw and may be contaminated with several foodborne pathogens. In order to guarantee the safety of seafood, real-time polymerase chain reaction (PCR) protocols may be used as these enable results to be provided within 24 h. The first goal of our work was to develop real-time PCR protocols enabling the detection of six foodborne pathogens that may be present in seafood products ( Campylobacter jejuni , Campylobacter coli , enterohemorrhagic Escherichia coli , Salmonella spp., Vibrio parahaemolyticus , and Vibrio vulnificus ). The corresponding gene targets were: 50S/VS1 , rfbE , ttr , tlh , and vvp . A multiplex PCR was also developed to detect the virulence genes of V. parahaemolyticus : tdh and trh . A total of 420 bacterial strains belonging to four different genera/strains were used in this study. Sensitivity and specificity were always 100%, except in the case of Salmonella spp., where three strains were not detected by our PCR protocols. The second objective of our work was to assess the detection limit of our real-time PCR protocols on artificially contaminated seafood products (raw shrimps, cooked shrimps, and raw mussels), purchased in public stores. Six different levels of contamination were assayed in four replicates for each matrix. The real-time PCR protocols enabled a better level of detection than the ISO methods, except for Salmonella in raw shrimps and for V. vulnificus in shrimps (raw and cooked). The estimated level of detection was between 1 and 47 cfu/25 g sample for the ISO norms and between 1 and 315 cfu/25 g sample for the real-time PCR protocols tailored in our work. The real-time PCRs developed in our work allowed for good selectivity, sensitivity, and specificity. The sensitivity on seafood products was estimated at a level of 100%, except for Salmonella (97%). In the spiking assays, the levels of detection were lower with the real-time PCR protocol than those obtained with the ISO method. This was not the case for V. vulnificus in raw and cooked shrimps and for Salmonella in raw shrimps. These real-time PCR protocols appear to be good alternative methods for surveillance of seafood products to ensure the absence of foodborne pathogens. One additional conclusion is that laboratories have to use enrichment media that are compatible with those recommended by ISO standards. This may facilitate the isolation of the pathogen if the real-time PCR protocol gives a suspect positive signal during the first step of the seafood analysis.

Effect of ante-mortem hypoxia on the physicochemical and functional properties of white shrimp (Litopenaeus vannamei) muscle stored on ice

The effect of ante-mortem hypoxia on the physicochemical and functional properties of raw and cooked white shrimp was studied. Hue angle was greater (p ≤ 0.05) for stressed raw shrimp compared to control (greener color); whereas a lower angle was detected for cooked stressed shrimp (redder/orange coloration). In addition, hue angle increased (p ≤ 0.05) over the ice storage period for control and stressed shrimp (raw and/or cooked). Muscle hardness and shear force showed no differences when comparing control and stressed shrimp (raw and/or cooked). However, during ice storage, shear force increased (p ≤ 0.05) by 22% and 9% for control and stressed raw shrimp, respectively; in contrast, shear force and muscle hardness decreased for cooked shrimp (p ≤ 0.05). Control showed more (p ≤ 0.05) elasticity than stressed cooked shrimp. Stressed raw shrimp showed a water holding capacity 10.8% lower (p ≤ 0.05) than control. However, during the storage, water holding capacity increased (p ≤ 0.05) reaching similar values to control after day 4. Muscle protein solubility of stressed shrimp was 31% lower than control; however, no differences (p > 0.05) were observed after the second day. The thermal stability of myosin (T max) showed differences (p ≤ 0.05) among control and stressed shrimp, whereas no differences for ΔH were observed. Results showed the influence of ante-mortem hypoxia on the physicochemical and functional properties of white shrimp muscle.