Quality and shelf life assessment of Pacific white shrimp (Litopenaeus vannamei) freshly harvested and stored on ice

Amine-responsive cellulose-based ratiometric fluorescent materials for real-time and visual detection of shrimp and crab freshness

Herein, we design and prepare cellulose-based ratiometric fluorescent materials with superior amine-response, which offers the real-time and visual detection of seafood freshness. Through utilizing the reactive hydroxyl groups along cellulose chains, we covalently immobilize the fluorescein isothiocyanate (FITC) as indicator and protoporphyrin IX (PpIX) as internal reference onto cellulose acetate (CA), respectively. Subsequently, a series of dual-emission solid fluorescent materials are achieved by simply blending green emitting CA-FITC with red-emitting CA-PpIX with varying ratios. They exhibit a sensitive, color-responsive, rapid and linear response to ammonia in a wide range of 5.0 ppm to 2.5 × 104 ppm. Benefiting from the excellent solubility and processibility of cellulose derivatives, the as-prepared materials are readily processed into different material forms, including printing ink, coating, flexible film, and nanofibrous membrane. The electrospun nanofibrous membrane is successfully employed as a low-cost, high-contrasting, quick-responsive fluorescent trademark for visual monitoring the freshness of shrimp and crab.

Cooperation of lactic acid bacteria regulated by the AI-2/LuxS system involve in the biopreservation of refrigerated shrimp

Litopenaeus vannamei is an extremely perishable food because of rapid microbial growth and chemical degradation after harvesting. Biopreservation is a food preservation technology based on the addition of "positive" bacteria to kill or prevent the growth of undesirable microorganisms. In this study, the cooperation between lactic acid bacteria (LAB) strains (Lactobacillus plantarum AB-1 and Lactobacillus casei) regulated by the AI-2/LuxS was investigated in vitro and on shrimp. The antimicrobial activity of L. plantarum AB-1 was significantly increased in the co-culture compared with the mono-culture in vitro, and the transcription of the quorum sensing luxS gene and bacteriocin regulatory operons (plnB and plnC) in L. plantarum AB-1 were also significantly increased in co-culture (P < .05), indicating cooperation and that the production of bacteriocin in L. plantarum AB-1 might be related to the LuxS/AI-2 quorum sensing (QS) system. The results were confirmed by adding the exogenous AI-2 molecule signal to L. plantarum AB-1 in vitro. In the on shrimp experiments, the spoilage organisms (mainly Shewanella baltica) in shrimp samples were significantly inhibited after co-inoculation with L. plantarum AB-1 and L. casei, and the values of total volatile basic nitrogen (TVB-N) and pH in co-inoculated shrimp were also significantly decreased (P < .05). In addition, the AI-2 activities in co-inoculated shrimp were significantly higher during refrigerated storage. The results suggest that the cooperation and bacteriocin production of lactic acid bacteria might by regulated by the AI-2/LuxS system, and the co-inoculation of L. plantarum AB-1 and L. casei in shrimp is an effective strategy for biopreservation of shrimp.

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

BACKGROUND

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.

RESULTS

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.

CONCLUSION

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.

Salmonella risks due to consumption of aquaculture-produced shrimp

The use of aquaculture is increasing to meet the growing global demand for seafood. However, the use of aquaculture for seafood production incurs potential human health risks, especially from enteric bacteria such as Salmonella spp. Salmonella spp. was the most frequently reported cause of outbreaks associated with crustaceans from 1998 to 2004. Among crustacean species, shrimp are the most economically important, internationally traded seafood commodity, and the most commonly aquaculture-raised seafood imported to the United States. To inform safe aquaculture practices, a quantitative microbial risk assessment (QMRA) was performed for wastewater-fed aquaculture, incorporating stochastic variability in shrimp growth, processing, and consumer preparation. Several scenarios including gamma irradiation, proper cooking, and improper cooking were considered in order to examine the relative importance of these practices in terms of their impact on risk. Median annual infection risks for all scenarios considered were below 10-4, however 95th percentile risks were above 10-4 annual probability of infection and 10-6 DALY per person per year for scenarios with improper cooking and lack of gamma irradiation. The greatest difference between microbiological risks for the scenarios tested was observed when comparing proper vs. improper cooking (5 to 6 orders of magnitude) and gamma irradiation (4 to 5 orders of magnitude) compared to (up to less than 1 order of magnitude) for peeling and deveining vs. peeling only. The findings from this research suggest that restriction of Salmonella spp. to low levels (median 5 to 30 per L aquaculture pond water) may be necessary for scenarios in which proper downstream food handling and processing cannot be guaranteed.

Changes in Lipid Profiles of Dried Clams ( Mactra chinensis Philippi and Ruditapes philippinarum) during Accelerated Storage and Prediction of Shelf Life

To predict the shelf life through an Arrhenius model and evaluate the changes in lipid profiles, two types of dried clams were stored at 50 and 65 °C and collected periodically for analysis. The predicted shelf life values of the two dried clam samples were 530 ± 14 and 487 ± 24 h (24 °C), and the relative errors between the actual and predicted values were 5.7 and 6.8%, respectively. During accelerated storage, the peroxide value, p-anisidine value, thiobarbituric acid-reactive substances value, total oxidation value, acid value, and free fatty acid content all increased, while the levels of triacylglycerol, phosphatidylcholine, phosphatidylethanolamine, major glycerophospholipid molecular species, and polyunsaturated fatty acid (PUFA) decreased. Moreover, content of phospholipid containing PUFA decreased significantly than that of triacylglycerol containing PUFA. Results indicated that the Arrhenius model was suitable for the shelf life prediction of dried clams and accelerated storage caused loss in quality of dried clams in terms of lipids.

Spoilage of refrigerated Litopenaeus vannamei: eavesdropping on Acinetobacter acyl-homoserine lactones promotes the spoilage potential of Shewanella baltica

Shewanella baltica and Acinetobacter are among the predominant spoilage bacteria in refrigerated shrimp (Litopenaeus vannamei). S. baltica are incapable of producing acyl-homoserine lactone (AHL) quorum sensing signals, but can respond to environmental AHLs. In this paper, Acinetobacter was found to produce three AHLs, i.e. N-butanoyl-l-homoserine lactone (C4-HSL), N-(3-oxohexanoyl)-l-homoserine lactone (O-C6-HSL) and N-(3-oxooctanoyl)-l-homoserine lactone (O-C8-HSL), according to thin-layer chromatography using the bioreporter Agrobacterium tumefaciens A136. The agar diffusion and β-galactosidase assays revealed that S. baltica could eavesdrop on these three AHLs from Acinetobacter. Eavesdropping on Acinetobacter AHLs especially C4-HSL was found to boost the growth of S. baltica particularly under nutrient limiting conditions (up to 40-fold increase) in the co-culture experiments. The azocasein assay revealed that S. baltica produced fourfold more extracellular proteases in response to Acinetobacter AHLs. As demonstrated by the biofilm crystal violet staining assay and confocal laser scanning microscopy, eavesdropping also decreased the biofilm-forming capacity of Acinetobacter. By inoculation of S. baltica and Acinetobacter onto surface-sterilized shrimp, eavesdropping was found to endow a growth advantage to S. baltica in vivo, resulting in a 0.5 day shortened shelf life of shrimp according to total volatile basic nitrogen levels and sensory analysis. Overall, the AHL-dependent eavesdropping increased the spoilage potential of S. baltica, providing a fresh perspective on the spoilage process of refrigerated L. vannamei, and this may inspire the development of novel preservation techniques in the future to further reduce post-harvest loss of shrimp.

Antibacterial activities and preservative effect of chitosan oligosaccharide Maillard reaction products on Penaeus vannamei

The purpose of this study was to understand the influence of Maillard reaction (MR) on bioactivity of chitosan oligosaccharide (COS). The antibacterial activity against Pseudomonas aeruginosa and Vibrio parahaemolyticus and preservative effect of two kinds of COS MR products (MRPs) on Penaeus vannamei were evaluated. The structures of CG (MRPs of COS and glucose) and CM (MRPs of COS and maltose) were characterized by FT-IR and their molecular weights were measured by gel permeation chromatography (GPC). The results showed that CG has enhanced antibacterial activity and preservative effect compared to COS by evaluating total volatile base-nitrogen (TVB-N), trimethylamine (TMA), pH, total bacterial count (TBC) and sensory evaluation. Meanwhile, CM showed decreased antibacterial activity and preservative effect compared to COS by evaluating TMA, pH and TBC. The results indicated that antibacterial activity and preservative effect of COS increased or decreased after MR. In other words, the type of reducing sugar involved in MR had a great impact on the functional properties of COS-saccharide MRPs and their application to be used as a food preservative.

Effects of different ozonized slurry-ice treatments and superchilling storage (-1°C) on microbial spoilage of two important pelagic fish species

Combining different preservative treatments for improving quality and safety of fishery products increasingly receives global research attention. Consistent with this pursuit, the current research was undertaken to determine the effects of different ozonized slurry-ice treatments and superchilling (-1°C) storage on microbial spoilage of European anchovy (Eugraulis encrasicolus) and sardine (Sardina pilchardus), which are two commercially important pelagic fish species. After the catch (within <5 hr) and at defined scheduled storage times, ozone has been discharged once on sardine (herein referred to as "One-T") and repeatedly/sequentially on European anchovy (herein referred to as "Seq-T"). Microbiological analyses enumerated total viable count (TVC), Bacillus spp., Enterobacteriaceae, Lactobacillus spp., Moraxella spp., Shewanella spp., Listeria monocytogenes and Pseudomonas spp. Independent of potential antimicrobial effects of ozone during superchilling storage, no Listeria spp., Shewanella spp., Moraxella spp., and Bacillus spp. were found in all processed samples. While Enterobacteriaceae and Lactobacillus spp. were detected at below 1 log cfu/g, both TVC and Pseudomonas spp. proliferated at different rates throughout superchilling storage. The repeated ozone-treated ("Seq-T") showed lower TVC and Pseudomonas spp. values compared with one-time treated ("One-T") slurry-iced and control samples. Thus, combined slurry-ice and superchilling storage at Seq-T produced improved antimicrobial activity over One-T application. Largely, ozonized slurry-ice outcomes/results appear promising thanks to superchilling storage.

Application of active edible coatings made from basil seed gum and thymol for quality maintenance of shrimp during cold storage

BACKGROUND

To improve the quality of Pacific white shrimp (Litopenaeus vannamei), active coating solutions were prepared by dissolving 10 g L^-1 of basil seed gum (BSG) and adding various levels of thymol (6%, 8% and 10% w/w based on gum weight) and glycerol (3.5 g L^-1 ) as plasticizer. The effects of coating solutions (CS1-4) on the quality changes of shrimps during refrigerated storage over 20 days were investigated.

RESULTS

The total volatile basic nitrogen (TVB-N) value in shrimps coated with CS4 (containing 10% w/w thymol) was slightly higher than the upper threshold of 300 mg kg^-1 on day 18, whereas that of uncoated shrimps increased to, or over, the threshold value on day 7. Active coatings significantly reduced (P < 0.05) microbial growth in shrimps during the cold storage without a negative impact on the organoleptic properties. Using CS4 on the shrimp samples immediately reduced total viable count and psychrotrophic bacteria count by 2 and 1 log colony forming units g^-1 , respectively, compared to controls.

CONCLUSION

The results of the present study revealed that the active edible coatings based on BSG activated with thymol had good potential to be used in the production of active packaging for various food applications. © 2016 Society of Chemical Industry.

Shelf-life extension of Pacific white shrimp using algae extracts during refrigerated storage

BACKGROUND

Shrimp is a low-fat, high-protein aquatic product, and is susceptible to spoilage during storage. To establish an effective method for the quality control of Pacific white shrimp, the effects of polyphenols (PP) and polysaccharides (PS) from Porphyra yezoensis on the quality of Pacific white shrimp were assessed during refrigerated storage. Pacific white shrimp samples were treated with 5 g L^-1 polyphenols, and 8 g L^-1 polysaccharides, then stored at 4 ± 1 °C for 8 days. All samples were subjected to measurement of total viable count (TVC), pH, total volatile basic nitrogen (TVB-N), K-value, thiobarbituric acid (TBA), polyphenol oxidase (PPO) activity, and were also assessed by sensory evaluation.

RESULTS

The results showed that PP, PS, and the mixture of polyphenols and polysaccharides (PP+PS) could inhibit the increase of total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA) and K-value, and reduce total viable count (TVC) compared with the control group. PP could also inhibit polyphenol oxidase (PPO) activity. Sensory evaluation proved the efficacy of PP and PS by maintaining the overall quality of Pacific white shrimp during refrigerated storage. Moreover, PP+PS could extend the shelf-life of shrimp by 3-4 days compared with the control group.

CONCLUSION

PP+PS could more effectively maintain quality and extend shelf-life during refrigerated storage. © 2016 Society of Chemical Industry.

Toward crustacean without chemicals: a descriptive analysis of consumer response using price comparisons

Background

To date, there seems to be limited-to-zero emphasis about how consumers perceive crustacean products subject to either chemical and or non-chemical preservative treatments. In addition, studies that investigated price comparisons of crustacean products subject to either chemical or chemical-free preservative methods seem unreported.

Objective

This study focused on providing some foundational knowledge about how consumers perceive traditionally harvested crustaceans that are either chemical-treated and or free of chemicals, incorporating price comparisons using a descriptive approach.

Design

The study design employed a questionnaire approach via interview using a computer-assisted telephone system and sampled 1,540 participants across five key locations in Italy. To actualize consumer sensitivity, ‘price’ was the focus given its crucial role as a consumption barrier. Prior to this, variables such as demographic characteristics of participants, frequency of purchasing, quality attributes/factors that limit the consumption of crustaceans were equally considered.

Results

By price comparisons, consumers are likely to favor chemical-free (modified atmosphere packaging) crustacean products amid a price increase of up to 15%. But, a further price increase such as by 25% could markedly damage consumers’ feelings, which might lead to a considerable number opting out in favor of either chemical-treated or other seafood products. Comparing locations, the studied variables showed no statistical differences (p>0.05). On the contrary, the response weightings fluctuated across the studied categories. Both response weightings and coefficient of variation helped reveal more about how responses deviated per variable categories.

Conclusions

This study has revealed some foundational knowledge about how consumers perceive traditionally harvested crustaceans that were either chemical-treated or subject to chemical-free preservative up to price sensitivity using Italy as a reference case, which is applicable to other parts of the globe.

Effect of spice-incorporated starch edible film wrapping on shelf life of white shrimps stored at different temperatures

BACKGROUND

White shrimps (Litopenaeus vannamei) are a major aquaculture product in the world fishery market. The main aim of this study was to investigate the effect of clove- and cinnamon-assimilated starch edible films on the shelf life of white shrimps in terms of maintaining their freshness and other organoleptic properties. Physical, chemical, microbial and sensory qualities of edible film-wrapped white shrimps were studied until they reached their limit of acceptability during storage at different temperatures (10 and 4 °C).

RESULTS

Shrimp samples wrapped with spice-assimilated edible films showed lower bacterial counts. Shelf life extension of edible film-wrapped white shrimps was estimated to be 14 and 12 days for storage at 10 and 4 °C respectively. Reduced lipid oxidation and release of nitrogen base compounds were noted for edible film-wrapped shrimp samples. Good consumer acceptance was noted for edible film-wrapped shrimp samples through sensory evaluation.

CONCLUSION

The results of this study show that spice-fused edible films were effective in inhibiting the growth of microbial populations. Reductions in lipid oxidation and total volatile base nitrogen were also achieved through edible film wrapping of shrimps, which increased their consumer acceptance during sensory evaluation. © 2016 Society of Chemical Industry.

Investigating the biometric and physicochemical characteristics of freshly harvested Pacific white shrimp (Litopenaeus vannamei): a comparative approach

BACKGROUND

The practicality of biometrics of seafood cannot be overemphasized, particularly for competent authorities of the shrimp industry. However, there is a paucity of relevant literature on the relationship between biometric and physicochemical indices of freshly harvested shrimp. This work therefore investigated the relationship between biometric (standard length (SL), total weight (TW) and condition factor (CF)) and physicochemical (moisture content, pH, titratable acidity, water activity, water retention index, colour values and fracturability) characteristics of freshly harvested Pacific white shrimp (Litopenaeus vannamei) obtained from three different farms. The relationships between these parameters were determined using correlation and regression analyses.

RESULTS

No significant correlation (P > 0.05) was found between the biometric and physicochemical indices of the sampled L. vannamei specimens. Possibly the lack of post-mortem and physical change(s) at day of harvest together with the absence of temporal variable may have collectively limited the degree of any significant correlation between biometric and physicochemical data points measured in this study. Although the TWs of freshly harvested L. vannamei shrimp resembled (P > 0.05), SL and CF differed significantly (P < 0.05) with minimal explained variance. Moreover, some biometric and physicochemical variables were independently correlated (P < 0.05).

CONCLUSION

Data indicated that no significant correlation existed between biometric and physicochemical characteristics of freshly harvested L. vannamei shrimp. Across the farms studied, however, the biometric data were comparable. To best knowledge, this is the first study to investigate the biometric and physicochemical properties of freshly harvested shrimp using a comparative approach, which is also applicable to other economically important aquaculture species. Overall, this work provides useful information for competent authorities/stakeholders of the fishery industry and serves as a baseline for preservative treatments.

Toward shrimp consumption without chemicals: Combined effects of freezing and modified atmosphere packaging (MAP) on some quality characteristics of Giant Red Shrimp (Aristaeomorpha foliacea) during storage

The combined effects of freezing and modified atmosphere packaging (MAP) (100% N2 and 50% N2+50% CO2) on some quality characteristics of Giant Red Shrimp (GRS) (Aristaeomorpha foliacea) was studied during 12-month storage. In particular, the quality characteristics determined proximal and gas compositions, melanosis scores, pH, total volatile basic-nitrogen (TVB-N), thiobarbituric acid (TBA) as well as free amino acid (FAA). In addition, the emergent data were compared to those subject to vacuum packaging as well as conventional preservative method of sulphite treatment (SUL). Most determined qualities exhibited quantitative differences with storage. By comparisons, while pH and TVB-N statistically varied between treatments (P<0.05) and TBA that ranged between ∼0.15 and 0.30 mg MDA/kg appeared least at end of storage for 100% N2 treated-group, the latter having decreased melanosis scores showed such treatments with high promise to keep the colour of GRS sample hence, potential replacement for SUL group. By comparisons also, while some individual FAA values showed increases especially at the 100% N2-treated group, the total FAAs statistically differed with storage (P<0.05). The combination of freezing and MAP treatments as preservative treatment method shows high promise to influence some quality characteristics of GRS samples of this study.

Effect of high hydrostatic pressure on the microbiological, biochemical characteristics of white shrimp Litopenaeus vannamei

Using thermal processing (TP) treatment (100 ℃, 1-8 min) as a control, the effects of high hydrostatic pressure (HHP, 200-500 MPa, 2.5-20 min) on the microbiological and biochemical characteristics of white shrimp Litopenaeus vannamei were investigated. The results showed that the efficiency of polyphenol oxidase (PPO) inactivation and log reduction of total plate count (TPC) by HHP treatment were all significantly lower than by TP treatment (p < 0.05). The rate of inactivation for TPC and PPO all increased with the increase of HHP pressure and holding time (p < 0.05). The inactivation of PPO was in accordance with a first-order kinetics with the HHP treating time. Hardness of HHP-treated samples at the pressure of 300-500 MPa was higher than TP-treated samples, while the yield loss of HHP treatment was significantly lower than with TP treatment (p < 0.05), long time and high pressure of HHP treatment turned the appearance of shrimps slightly pink.