Charles Odilichukwu R. Okpala

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.

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.

Hazardous properties and toxicological update of mercury: From fish food to human health safety perspective

ABSTRACT The mercury (Hg) poisoning of Minamata Bay of Japan widely activated a global attention to Hg toxicity and its potential consequences to the aquatic ecosystem and human health. This has resulted to an increased need for a dynamic assembly, contextualization, and quantification of both the current state-of-the-art and approaches for understanding the cause-and-effect relationships of Hg exposure. Thus, the objective of this present review is to provide both hazardous toxic properties and toxicological update of Hg, focusing on how it ultimately affects the aquatic biota to potentially produce human health effects. Primarily, we discussed processes that relate to Hg exposure, including immunological aspects and risk assessment, vulnerability, toxicokinetics, and toxicodynamics, using edible fish, swordfish (Xiphias gladius), as a model. In addition, we summarized available information about Hg concentration limits set by different governmental agencies, as recognized by national and international standardization authorities.

Lighting Methods Employed in Harvest of Fishery Products: A Narrative Review

Fishermen since time immemorial have employed various lighting methods aimed for favourable/successful harvest of fishery products. The latter on the other hand have evolved with habitat constituents for example, the waters, light and other external factors, which contribute to evolve the sensory adaptations. Whilst there is considerable literature about lighting approaches/methods employed in harvest of fishery products, no appraisal concerning the state-of-the-art to best of our knowledge has been performed. In this review, (some) relevant information about lighting methods employed in harvest of fishery products will be summarized under the following sub-headings: (a) Light as resource for fishing; (b) Eye of fish for vision and survival; (c) Catching the fish with light: experimental methods and instrumentation; (d) Light intensities that looks at: (i) attraction and reaction of fish; (ii) active escape of fish; (iii) induced stress of fish; as well as (e) Simulated trawls and conducted surveys. Some recommendations to direct future studies are also summarized.

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

Abstract 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.

On the Acclimatization of Pelagic Fish Species Juveniles in a Closed Environment: An Atlantic Horse Mackerel Case Study

Understanding how fish species acclimatize to a new environment may help to improve aquatic/fisheries resource management. Further, baseline information specific to behavior patterns of (pelagic) fish species juveniles particularly during acclimatization appears unreported to best of our knowledge. Therefore, the current study was goaled to examine the acclimatization of pelagic fish species juveniles in a closed environment using Trachurus trachurus as a case reference. Eighteen Trachurus fish juveniles were maintained in well-kept seawater-filled aquarium under laboratory/room conditions of controlled temperature. The characteristic observations of fish aggregation, fish-to-feed movement and fish-feed selection that varied across begin (days 1-5), middle (days 6-15) and end (days 16-20) phases provided substantiations about either how and when Trachurus spp. juveniles started, increased and or achieved complete/full acclimatization behavior. The initial peak (laboratory/room = ~18°C; water = ~20°C) temperatures of 20-day acclimatization period would stabilize with time. Along with the abovementioned characteristic observations, water temperatures seemed to fluctuate more compared to laboratory/room. Overall, the current study provides noteworthy baseline knowledge about pelagic fish juveniles’ behavior(s)/pattern(s) in closed environment and useful reference for future acclimatization studies.

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.