Peeled Shrimp Research Articles

Effect of kappa-carrageenan oligosaccharides on myofibrillar protein oxidation in peeled shrimp (Litopenaeus vannamei) during long-term frozen storage

Protein oxidation during chilling and frozen storage has recently attracted great attention due to its consequences on protein solubility and functionality. In this study, the effects of kappa-carrageenan oligosaccharides on myofibrillar protein oxidation in peeled shrimp (Litopenaeus vannamei) during frozen storage were investigated by assessing the content of the carbonyls, total sulfhydryl, dityrosine, and surface hydrophobicity. We also examined the means of antioxidant activity in vitro, degradation of muscle proteins, and integrity of tissue structure. Our data revealed that in vitro carrageenan oligosaccharides exhibited good capacities of OH, O2−, and DPPH· scavenging and Fe2+-chelating activity. Chemical analyses showed that frozen storage increased susceptibility of myofibrillar proteins to frozen oxidation. We found that the incorporation of carrageenan oligosaccharides during the treatment of the shrimp prior to frozen storage significantly decreased the formation of protein carbonyl and dityrosine, lowered the changes in myofibrillar surface hydrophobicity, and maintained a higher total sulfhydryl content when compared with the water-treated samples (control). Additionally, the results of protein degradation and tissue structure confirmed that these antioxidant oligosaccharides exhibited marked effects on stability of muscle proteins and effectively inhibited the degradation/oxidation of muscle proteins during frozen storage. Overall, the contribution of the antioxidant activities played an important role in cryoprotective effects of carrageenan oligosaccharides on frozen shrimp. Further application of these findings might maintain better quality and extend the commercialization of refrigerated products.

The cryoprotectant effect of xylooligosaccharides on denaturation of peeled shrimp (Litopenaeus vannamei) protein during frozen storage

The cryoprotective effects of xylooligosaccharides on peeled whiteleg shrimp were investigated and compared with sodium pyrophosphate treatment during frozen storage, primarily the interaction mechanisms between xylooligosaccharides and shrimp myosin. Data revealed that soaking in the xylooligosaccharides solutions prior to frozen storage markedly reduced thawing and cooking losses in frozen shrimp, which were significantly lower than that of fresh water treatment. The significant inhibitory effects on textural variables (springiness and chewiness) in oligosaccharides-treated shrimp were also found, compared to the control samples. Chemical analyses showed that these oligosaccharides maintained a higher myofibrillar protein content and Ca2+-ATPase activity in frozen shrimp. Additionally, the hematoxylin and eosin staining results indicated that the oligosaccharides significantly slowed the damage to muscle tissue structures. Our assumption was that water replacement hypothesis played a leading role in cryoprotection of frozen shrimp in this study, as shown in previous experimental results and reports. Furthermore, the homology modeling and molecular dynamics simulations confirmed that the oligosaccharides substituted water molecules around shrimp myosin surface by forming hydrogen bonds with polar residues of amino acids, thereby stabilizing the structures in the absence of water, leading to an increase in protein stability during frozen storage. Overall, the contribution of the water-replacement activities played an important role in cryoprotective effects of this oligosaccharides on frozen shrimp. Further application of these findings might maintain better quality and extend the commercialization of refrigerated shrimp products.

The Effectiveness of Official Methods to Measure the Real Glazing Percentage in Frozen Seafood: An Analysis with Frozen Pacific White Shrimp (L. vannamei)

ABSTRACTThe aim of this study was to evaluate the effectiveness of official methods to quantify the real glazing percentage in frozen Pacific white shrimp (Litopenaeus vannamei) with different glazing percentages. Samples of frozen peeled shrimp were glazed with cold water (0 ± 1°C) at glazing levels of 15, 30, 40, 50, and 60%. The glazing percentage was quantified based on Brazilian methodologies (INMETRO and MAPA) and International methodologies (CODEX, AOAC, and NIST). The official methods were inefficient in quantifying the real glazing percentage, especially with regard to the samples containing higher glazing percentages (> 30%). As an alternative, changes were done to improve the glazing measurement method (mix of the best parameters from all methodologies), which best describes the reliable value of the glazing percentage of frozen shrimp samples and confirms that this methodology can be an alternative used by inspectors after collaborative study for validation. In this sense, a critical review and possible changes in the official methodologies may be suggested in order to improve them for use to combat economic fraud in the seafood frozen products.

Effect of commercial probiotic (Protexin®) on growth, survival and microbial quality of shrimp (Litopenaeus vannamei)

PurposeThe purpose of this study was to investigate the effect of a dietary probiotic on the growth performance and survival rate of Litopenaeus vannamei shrimp. Furthermore, the microbial quality of shrimp was evaluated.Design/methodology/approachShrimp were divided into treatment and control groups (each group containing 45 shrimp). They were fed for four weeks with a control diet alone or supplemented with a commercial probiotic (Protexin®). At the end of the trial, they were assessed for survival rate, weight gain, average daily gain and specific growth rate. Samples of tail meat were also provided aseptically from peeled shrimp for bacteriological analysis including the count of Staphylococcus aureus, enterococci, Clostridium perfringens, fecal coliform, Salmonella, Escherichia coli, Listeria monocytogenes and total bacterial count.FindingsThe growth performance of the probiotic-treated group significantly (p < 0.05) increased at the end of the experimental period. However, no significant differences were observed for the survival rate between the groups (p > 0.05). The count of C. perfringens and the total bacterial count in shrimp supplemented with the probiotic were significantly lower than those of controls (p < 0.05). The count of coliforms and S. aureus was not significantly different between the groups (p > 0.05).Originality/valueIt could be concluded that the probiotic bacteria have the potential to stimulate the growth performance of L. vannamei. They can also be used for biological control of food-borne pathogens and improve the microbial quality and safety of shrimp at the farm level.

Cryoprotective roles of trehalose and alginate oligosaccharides during frozen storage of peeled shrimp (Litopenaeus vannamei).

Cryoprotective saccharides are widely accepted additives that reduce thawing loss, maintain texture, and retard protein denaturation in the frozen seafood. The present study aimed to investigate the roles of trehalose and alginate oligosaccharides on cryoprotection of frozen shrimp, primarily focusing on the interactions between myosin and saccharide molecules using a molecular dynamics (MD) simulation analysis. The results indicated that soaking in the trehalose and alginate oligosaccharides solutions markedly reduced thawing and cooking losses in frozen shrimp, with respective values decreasing to 6.02%, 8.14%, and 5.99%, 8.19% after 9weeks of storage, which were significantly lower than that of fresh water treatment (9.75% and 15.09%). Our assumption was that water replacement played a leading role in cryoprotection, as shown in previous experimental results and reports. Furthermore, homology modeling and MD simulations confirmed that trehalose and alginate oligosaccharides substituted the water molecules around the myosin surface by forming hydrogen bonds with polar residues of amino acids, thereby stabilizing the structures in the absence of water during frozen storage. These conditions affected the flexibility of particular amino acid residues, enhanced the residue cross correlations within the two chains of myosin, and also increased the total interaction energy between myosin and water/saccharide molecules, thereby leading to an increase in protein stability. Finally, by comparing the experimental results to that of MD simulation, significant positive correlation existed between saccharides and the stabilization of myosin in shrimp muscle. The findings of the present study may help better understand the cryoprotective mechanisms of saccharides in frozen shrimp, and the two saccharides may be potentially used as alternative additives in seafood to maintain better quality during frozen storage.

Application of chitosan and gelatin based active packaging films for peeled shrimp preservation: A novel functional wrapping design

The aim of the present study was to evaluate the effects of chitosan (Ch) and gelatin (Ge) films containing Ziziphora clinopodioides essential oil (ZEO; 0 and 1%), pomegranate peel extract (PPE; 0 and 1%) and cellulose nanoparticle (CN; 0 and 1%), separately and in combination, on survival of Listeria monocytogenes and shelf life extension of fresh shrimp during refrigerated storage. The control and wrapped shrimps were evaluated for chemical (PV and TVB-N), bacterial (mesophilic and psychrotrophic bacteria, Pseudomonas spp., P. fluorescens, Shewanella putrefaciens, lactic acid bacteria and Enterobacteriaceae) and sensory properties (odor, color, texture and acceptability). All wrapped shrimps in Ch and Ge films had lower bacterial counts compared to control (P < 0.05). Final population of L. monocytogenes was decreased 2–3 log CFU/g in treated samples compared to control (P < 0.05). The bacterial population of shrimps wrapped in Ch films were significantly lower than those wrapped in Ge films probability due to the inherent antibacterial property of Ch (P < 0.05). The groups treated with CN had insignificantly lower bacterial count compared straight film (P > 0.05). The Ch group treated with ZEO 1% + PPE 1% + CN 1% had the best antibacterial effectiveness and also the highest organoleptic scores after 11 days (P < 0.05).

Improvement of the microbiological quality of ready-to-eat peeled shrimps (Penaeus vannamei) by the use of chitosan coatings

Chitosan coatings incorporated with 0.5% of oregano and thyme EO were applied onto ready-to-eat peeled shrimp tails and packed under MAP conditions. The growth of naturally present spoilage microorganisms was evaluated for 12days during chilled storage (4°C). Coatings containing thyme EO were more effective in inhibiting the microbial species studied, specially lactic acid and psychrotrophic bacteria. As carrier of EOs, chitosan was more effective in inhibiting the growth of bacteria present in peeled shrimps than the direct application of an oil-water (O/W) emulsion. Finally, results from sensory analysis showed that the sensorial quality was affected by the chitosan-thyme coatings despite characteristics like firmness and colour were kept. The present work demonstrates the effectiveness of chitosan enriched coatings, offering a promising alternative to control the growth of spoilage and pathogen microorganisms on peeled shrimps during refrigeration storage.

Assessment of Food Poisoning Bacteria in Some Frozen Fish and Fish Products

Consumption of frozen fish and fish products has increased worldwide. Levels of Escherichia coli, Staphylococcus aureus, Salmonella Typhimurium and Listeria monocytogenes in frozen fish products marketed in Cairo and Sharkia Governorates, Egypt, were investigated. A total of 150 samples including peeled shrimp, surimi, fish fillet, oyster and lobster tail (30, each) were examined. The overall contamination rate of frozen fish products was 6%. E. coli , L. monocytogenes and S. Typhimurium were identified in 2.7%, 2% and 1.3% of the examined samples, respectively. Health and food safety organizations should follow up fish products in all markets and apply the laws that prevent selling any fish products of unknown sources. Moreover, to ensure safety of fishery products, improvement of hygienic processing and handling from fish farming to markets is recommended.

4-Hexylresorcinol 침지액 농도와 침지시간에 따라 새우의 갈변도 및 4-Hexylresorcinol 잔류량에 미치는 영향

껍질을 제거하지 않은 새우의 경우 10일 동안 저장하는 과정에서 갈변이 심각하게 진행된 것을 확인할 수 있었다. 갈변은 두흉부, 등껍질 그리고 꼬리 순서로 진행되었으며, 4-hexylresorcinol 침지액에 의해 갈변이 억제될 경우 꼬리, 등껍질 그리고 두흉부 순서로 억제되었다. 껍질을 제거하지 않은 새우의 경우 10, 20 mg/L 4-hexylresorcinol 침지액 농도에서 72시간 침지한 새우로부터 각각 1.36, 2.33 mg/kg의 잔류농도를 확인하였으며, 해외에서 규정하고 있는 최대잔류수준 이상의 4-hexylresorcinol이 검출되어 갈변억제 효과는 있었지만 사용방법으로 부적합한 것으로 나타났다. 껍질을 제거한 새우의 경우에는 가식부위가 직접 침지액에 침지되기 때문에 대부분의 새우에서 1 mg/kg 이상의 4-hexylresorcinol 잔류량이 확인되었으며, 껍질을 제거한 새우를 20 mg/L 4-hexylresorcinol 침지액에 72시간 동안 침지한 처리군에서 13.46 mg/kg으로 가장 높은 4-hexylresorcinol 잔류량이 확인되었다. 이러한 결과는 캐나다 및 중국뿐만 아니라 유럽에서 규정하고 있는 최대잔류수준을 초과함에 따라서 새우의 침지 조건으로 새우 껍질을 제거한 뒤 침지하는 방법은 적합하지 않은 것으로 판단되며, 갈변억제 효과는 20 mg/L 4-hexylresorcinol 침지액에서 24시간 동안 침지한 처리군에서 가장 높은 억제 효과를 나타내었다. 본 연구 결과 4-hexylresorcinol 침지액 농도와 침지시간에 따라 4-hexylresorcinol 잔류량 및 갈변억제 효과에 높은 상관관계를 나타내었으며, 규정에 제시되어 있는 최대잔류허용량을 초과하지 않고 효율적인 갈변억제 효과를 얻기 위한 방법으로는 껍질을 제거하지 않은 새우에서 20 mg/L 4-hexylresorcinol 침지액에서 24시간 동안 침지처리하는 방법이 가장 적절한 것으로 확인되었다.

Release of cinnamon essential oil from polysaccharide bilayer films and its use for microbial growth inhibition in chilled shrimps

Active biodegradable bilayer films based on agar and sodium alginate were developed by the incorporation of cinnamon essential oil in the upper layer. The release of both cinnamaldehyde and eugenol from the agar and alginate bilayer films into water at 4 °C and 20 °C did not increase significantly from 9 h onwards, and consequently increasing values of antioxidant activity measured by ferric reducing ability and radical scavenging capacity were observed until 9 h in both cases. Agar bilayer films showed an antimicrobial activity approximately 1.4-fold higher than the alginate bilayer films, although both of them were effective against all the microorganisms tested in this study, especially against Photobacterium phosphoreum. Both agar and alginate bilayer films allowed to reduce significantly the microbial growth, including the pathogenic bacteria Listeria monocytogenes, in peeled shrimps during the chilled storage without a negative impact on the organoleptic properties.

Evaluation of the Thermo Scientific™ SureTect™ Salmonella species Assay.

The Thermo Scientific™ SureTect™ Salmonella species Assay is a new real-time PCR assay for the detection of Salmonellae in food and environmental samples. This validation study was conducted using the AOAC Research Institute (RI) Performance Tested MethodsSM program to validate the SureTect Salmonella species Assay in comparison to the reference method detailed in International Organization for Standardization 6579:2002 in a variety of food matrixes, namely, raw ground beef, raw chicken breast, raw ground pork, fresh bagged lettuce, pork frankfurters, nonfat dried milk powder, cooked peeled shrimp, pasteurized liquid whole egg, ready-to-eat meal containing beef, and stainless steel surface samples. With the exception of liquid whole egg and fresh bagged lettuce, which were tested in-house, all matrixes were tested by Marshfield Food Safety, Marshfield, WI, on behalf of Thermo Fisher Scientific. In addition, three matrixes (pork frankfurters, lettuce, and stainless steel surface samples) were analyzed independently as part of the AOAC-RI-controlled laboratory study by the University of Guelph, Canada. No significant difference by probability of detection or McNemars Chi-squared statistical analysis was found between the candidate or reference methods for any of the food matrixes or environmental surface samples tested during the validation study. Inclusivity and exclusivity testing was conducted with 117 and 36 isolates, respectively, which demonstrated that the SureTect Salmonella species Assay was able to detect all the major groups of Salmonella enterica subspecies enterica (e.g., Typhimurium) and the less common subspecies of S. enterica (e.g., arizoniae) and the rarely encountered S. bongori. None of the exclusivity isolates analyzed were detected by the SureTect Salmonella species Assay. Ruggedness testing was conducted to evaluate the performance of the assay with specific method deviations outside of the recommended parameters open to variation (enrichment time and temperature, and lysis temperature), which demonstrated that the assay gave reliable performance. Accelerated stability testing was additionally conducted, validating the assay shelf life.

Fresh-Keeping Effects of Melanin-Free Extract From Squid Ink on Yellowfin Sea Bream (Sparus latus) During Cold Storage

Squid ink, a by-product from the squid production process, has been demonstrated to be a multifunctional marine bioactive material that can promote freshness of shiokara and peeled shrimp. However, the preservative effect it has on marine fish as well as its preservative mechanisms are still unknown. In this article, Sparus latus was used as a model to assess the preservative effects and the possible mechanism of the ink through chemical parameters, antibacterial effect, and sensory analysis. Melanin-free extract from squid ink at a concentration of 45 mg/mL and pH 8.5 was revealed to be effective in prolonging cold storage shelf life of Sparus latus, which was confirmed through comprehensive sensory analysis evaluation and measurement of chemical changes including pH, microbial count, total volatile basic nitrogen (TVB-N) value, and nucleotide analysis. It was also discovered that the extract mainly suppressed putrefying bacteria separated from Sparus latus, and the bacteriostatic range was confirmed to be wide. Squid ink significantly prolonged the cold storage period of Sparus latus, indicating that it may be developed to be a natural preservative for marine products.

Modeling the thermoultrasound inactivation of Vibrio parahaemolyticus in raw peeled shrimps.

Vibrio parahaemolyticus has been identified as a causative agent for seafoodborne diseases worldwide. The effect of thermoultrasound treatment on the survival of V. parahaemolyticus in raw peeled shrimps was investigated in this study as an alternative bacterial inactivation method in seafood as part of the postharvest washing process. Raw peeled shrimps inoculated with V. parahaemolyticus were treated with mild heat (47, 50, and 53°C) combined with ultrasound (0, 96, 150, and 204 W) based on a 3 × 4 full factorial design, and the bacterial survival curves were fitted with a Weibull model. Because of the high correlations of the shape parameter n and the scale parameter β in the Weibull model, an overall n was estimated from the whole set of bacterial inactivation data and β values were estimated for each set of inactivation curves accordingly. A response surface model was generated to describe the scale parameter as a function of temperature and ultrasonic power. The results indicated that the Weibull model with the overall n value could be used to describe the bacterial reduction with the time of exposure to the thermoultrasound treatments, which was well supported by the small root mean square errors (RMSE) and the high coefficients of determination (R(2)). The quadratic model was validated with independent experiments within the prediction range. Statistical indices (R(2) = 0.99; P < 0.0001; RMSE = 0.17) and validation parameters (bias factor = 0.97; accuracy factor = 1.03) indicated satisfactory performance of the quadratic model. The results indicated that the thermoultrasound treatment is effective, simple, and cost-effective for inactivation of V. parahaemolyticus in shrimps during the postharvest washing process.

Cooking properties of the peeled shrimp on the market

Cooking properties of the peeled shrimp on the market

Food Processing Trials Using Underwater Shock Wave by Electrical Discharge

We propose a new method for the efficient decompression of frozen food under high dynamic pressure. Two experiments are conducted on an ice block containing peeled shrimp: wire explosion and underwater shock wave. In these experiments, the ice is finely crushed, while the frozen peeled shrimps retain their original shape and can be efficiently extracted. Since ice crushing is performed momentarily, the defrosting time is significantly shorter than that in traditional thawing techniques, such as melting in running water or cold-water soaking. This new method could increase the efficiency of food production processes.

Preparation of an novel botanic biopreservative and its efficacy in keeping quality of peeled Penaeus vannamei

A novel botanic biopreservative was successfully prepared by the combination of the bamboo leaves extracts and ebony extracts, designated as ebony-bamboo leaves complex extracts (EBLCE), whose antimicrobial activity was assessed according to an inhibition zone method against 10 common pathogenic and spoilage microorganisms. It was found that EBLCE was more effective from all the chosen microorganisms, as compared by potassium sorbate. Due to its excellent antimicrobial activity, and some additional properties like edibility, safety and economy, EBLCE was selected for further study to evaluate the efficacy in prolonging shelf life and improving the quality of peeled Penaeus vannamei during storage at 4 °C, based on periodical microbiological, chemical and sensory analysis. As a result, EBLCE was observed to prevent spoilage of peeled P. vannamei efficiently as reflected by a distinct decrease in total viable count, pH and total volatile basic nitrogen, as well as a slower decline in the sensory evaluation scores. Therefore, a prolonged shelf life of 16 days was obtained for EBLCE pre-treated peeled shrimps with comparison of 6 days for the control group, demonstrating EBLCE as a promising alternative for preserving food.

Influence of temperature, pH and NaCl concentration on the maximal growth rate of Brochothrix thermosphacta and a bioprotective bacteria Lactococcus piscium CNCM I-4031

The maximum specific growth rate (μmax) of Brochothrix thermosphacta, a spoilage bacteria of cooked peeled shrimp, and Lactococcus piscium CNCM I-4031, a bioprotective strain, was investigated under different conditions of temperature, NaCl concentrations and pH. The basic modelling approach used was the Gamma concept (γ-concept) and the model developed was then adapted to shrimp. Cardinal growth parameters were quite similar for the two strains, except for NaCl. No NaCl was required for growth and the NaClmax was three-times higher for B. thermosphacta than for L. piscium (62 and 23 g l−1 respectively). However, tolerance to NaCl was higher in seafood than in liquid broth, possibly due to presence of osmoltically active molecules. L. piscium and B. thermosphacta were psychrotolerant, with Tmin = −4.8 and −3.4 °C, Topt = 23.4 and 27.0 °C and Tmax = 27.2 and 30.8 °C respectively. The optimal pH was neutral and growth possible till pH = 4.8 for the two strains, assuming possible applications of the bioprotective strain in lightly marinated seafood. The μmax of B. thermosphacta in shrimp was a little higher than in L. piscium whatever the environmental conditions. Validation of the model showed that the γ-concept was suitable for predicting μmax of B. thermosphacta in shrimp. Data generated in this study can be used to adapt the model to other foods with few additional experiments and the effect of different parameters may be added in the future. The model was less accurate for the bioprotective strain and the effect of NaCl must be studied in more detail directly in the matrix.

Detection of potentially pathogenic Aeromonas isolates from ready‐to‐eat seafood products by PCR analysis

SummaryThis study provides data on the prevalence of potentially pathogenic Aeromonas spp. in ready‐to‐eat (RTE) seafood products by evaluating the occurrence of Aeromonas spp. and the presence of virulence‐associated genes. Aeromonas spp. was detected in 57/81 (70.3%) RTE seafood samples. Specifically, Aeromonas spp. was highlighted in 19/21 (90.5%) sushi, in 18/21 (85.7%) sea salad, 11/12 (91.7%) surimi and 9/12 (75%) peeled shrimp samples. Aeromonas spp. was not observed in marinated anchovies and octopus salad samples. Then, PCRs aimed at the hlyA, aerA, alt and ast genes, encoding, respectively, haemolysin A, aerolysin, aeromonas labile temperature cytotonic enterotoxin and aeromonas stable temperature cytotonic enterotoxin, demonstrated a widespread distribution of these genes among Aeromonas isolates. The results underline the need to implement an adequate control plan performing an intensive and continuous monitoring to guarantee the human health.

EFFECT OF ROSEMARY ON THE QUALITY CHARACTERISTICS OF WHITE SHRIMP (LITOPENAEUS VANNAMEI)

ABSTRACTWe assessed the influence of rosemary on some of the quality characteristics of Litopenaeus vannamei shrimp stored under freezing temperature for 180 days. Whole shrimp (WS), peeled shrimp (PS) and PS with dehydrated rosemary (RS) were stored at −28.3 ± 3.8C. Physicochemical and sensorial analysis was carried out. After 180 days, RS had lower pH (P = 0.001) and thiobarbituric acid‐reactive substances (TBARS; P = 0.001) values and higher carotenoids (P = 0.003). WS samples were firmer at 180 days (P = 0.001), although rancid taste and smell were perceived with greater intensity (P = 0.001). The color was more intense in RS and PS than in WS (P = 0.030). Rancid taste was detected in RS only at 120 days at significantly lower intensity (P = 0.001) than WS and PS. Our study suggests that dehydrated rosemary can improve the quality of frozen L. vannamei peeled shrimp.PRACTICAL APPLICATIONSFarmed shrimp has gained importance in the global market, and the study of their physicochemical and sensory characteristics is therefore essential. Commercially, shrimp is mainly available in the frozen form, and alternatives to extend its quality during storage are of great interest for consumers and suppliers in the food industry. Dehydrated rosemary can be added to frozen shrimp to improve its quality and maintain the nutritional characteristics during storage.

Sensory and physicochemical evolution of tropical cooked peeled shrimp inoculated by Brochothrix thermosphacta and Lactococcus piscium CNCM I-4031 during storage at 8°C

This study investigated the sensory quality and physicochemical evolution (pH, glucose, l-lactic acid, biogenic amine, free amino-acids and volatile compounds) during storage at 8°C of cooked peeled shrimp inoculated with the specific spoilage bacteria Brochothrix thermosphacta alone or mixed with the protective strain Lactococcus piscium CNCM I-4031. Growth of both bacteria was monitored at regular intervals during storage by microbial counts and the thermal temperature gradient gel electrophoresis (TTGE) technique. Bacterial counts showed that L. piscium and B. thermosphacta inoculated at 7 log CFU/g and 3 log CFU/g were well adapted to shrimp, reaching a maximum level of 9 log CFU/g after 4days and 10days respectively. In mixed culture, the growth of B. thermosphacta was reduced by 3.2±0.1 log CFU/g. The TTGE technique allowed monitoring the colonisation of the strains on the shrimp matrix and confirming the dominance of L. piscium in mixed culture throughout the experiment. Sensory analysis confirmed that B. thermosphacta spoiled the product after 11days, when its cell number attained 8 log CFU/g with the emission of strong butter/caramel off-odours. This sensory profile could be linked to the production of 2,3 butanedione, cyclopentanol, 3-methylbutanol, 3-methylbutanal, 2-methylbutanal, 4-methyl-3-chloro-3-pentanol and ethanol, which were produced in more significant quantities in the B. thermosphacta batch than in the batches in which the protective strain was present. On the contrary, TVBN and TMA were not suitable as quality indicators for B. thermosphacta spoilage activity. In the products where the protective L. piscium strain was present, no adverse effect on sensory quality was noted by the sensory panels. Moreover, biogenic amine assessment did not show any histamine or tyramine production by this strain, underlining its safety profile. Both strains produced lactic acid (1850mg/kg in L. piscium and B. thermosphacta batch on days 3 and 10 respectively; 3830mg/kg on day 7 in mixed culture) and the pH decrease from 6.6±0.0 to 5.9±0.1 was similar in all batches. Lactic acid production or competition for free amino-acid was not involved in the inhibition mechanism; however rapid glucose consumption by L. piscium could partially explain the growth limitation of the spoilage micro-organism. This study demonstrated the spoilage characteristic of B. thermosphacta and the usefulness of L. piscium as a bioprotective culture for tropical cooked peeled shrimp without any adverse effect on the sensory quality of the product.