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

Effectiveness of a formulation based on Ocimum gratissimum essential oil and cashew gum as inhibitors of quality loss and melanosis in shrimp

In this study, two nanoemulsions were formulated with essential oil (EO) of Ocimum gratissimum with (EON) or without (EOE) cashew gum (CG). Subsequently, inhibition of melanosis and preservation of the quality of shrimp stored for 16 days at 4 ± 0.5 °C were evaluated. A computational approach was performed to predict the system interactions. Dynamic light scattering (DLS) and atomic force microscopy (AFM) were used for nanoparticle analysis. Gas chromatography and flame ionization detector (GC-FID) determined the chemical composition of the EO constituents. Shrimps were evaluated according to melanosis's appearance, psychrotrophic bacteria's count, pH, total volatile basic nitrogen, and thiobarbituric acid reactive substances. EON exhibited a particle size three times smaller than EOE. The shrimp treated with EON showed a more pronounced sensory inhibition of melanosis, which was considered mild by the 16th day. Meanwhile, in the other groups, melanosis was moderate (EOE) or severe (untreated group). Both EON and EOE treatments exhibited inhibition of psychrotrophic bacteria and demonstrated the potential to prevent lipid oxidation, thus extending the shelf life compared to untreated fresh shrimp. EON with cashew gum, seems more promising due to its physicochemical characteristics and superior sensory performance in inhibiting melanosis during shrimp preservation.

Portable and reversible smart labels for non-destructive detection of seafood freshness via amine-response fluorescent ionic liquids

Herein, a functionalized ionic liquid (IL) 7-HDCP (7-hydroxycoumarin-quaternary phosphorus) was developed as NH3 trapping agents and fluorescent indicators to achieve in-time and on-site detection of seafood freshness. Interestingly, the IL displayed remarkable blue fluorescence "turn-on" enhancement to gaseous amine due to excellent amine solubility. By FTIR and 1H NMR spectrogram, this fluorescence "turn-on" phenomenon originated from the weak hydrogen bonding between the ester group of the coumarin functional group and the ammonia molecule. Moreover, the IL exhibited a rapid response (<11 s), prominent sensitivity (0.12 ppm), excellent selectivity (10 interfering substances) and outstanding reversibility (>22 cycles). Benefiting from ion characters, 7-HDCP obtained advantages of easy-to-fabricate and easy-to-use, which was fabricated by one-step simple immersion without aggregation-caused quenching phenomenon. This portable and sensitive smart label made of ion probes facilitates the timely and on-site NH3 detection in the early deterioration stages of aquatic products, enabling "early detection, early warning, and early treatment".

Impact of Ethanolic Thai Indigenous Leaf Extracts on Melanosis Prevention and Shelf-Life Extension of Refrigerated Pacific White Shrimp

Shrimp has been known for its delicacy, but it undergoes rapid deterioration induced by biochemical and microbiological reactions. Melanosis is a major cause of discoloration associated with consumer rejection. All ethanolic extracts from different leaves including soursop, noni, and Jik leaves were dechlorophyllized via the "Green" sedimentation method before being used. The inhibitory activity against polyphenoloxidase (PPO) from Pacific white shrimp (Litopeneous vannamei) and the copper-chelating properties of varying extracts were compared. Soursop leaf extract (SLE) showed higher PPO inhibitory activity and copper-chelating ability than others (p < 0.05). Based on LC-MS, aempferol-3-O-rutinoside was identified as the most abundant compound, followed by catechin and neocholorigenic acid. The efficacy of SLE at different levels (0.25-1%) for inhibiting melanosis and preserving the quality of Pacific white shrimp was evaluated during refrigerated storage at 4 °C for 12 days in comparison with that of a 1.25% sodium metabisulfite (SMS)-treated sample. SLE at a level of 1% effectively retarded melanosis and bacterial growth, in which the total viable count did not exceed the microbial limit within 12 days. In addition, 1% SLE treatment impeded autolysis, reduced protein degradation and decomposition, and minimized lipid oxidation, as witnessed by the lower increases in pH, TVB-N, and TBARS values. Sensory evaluation indicated higher likeness scores and overall acceptability for SLE-1% and SMS-1.25% shrimps than those of the control and other samples. Therefore, SLE could be used as a natural alternative that effectively lowered the melanosis and quality loss of shrimp during refrigerated storage.

A colorimetric and fluorescent sensor for non-destructive screening of the freshness of shrimp and fish

The freshness of fish and shrimp is closely associated with food safety, hence it is a wide concern to develop a facile and effective method for fast, non-destructive and visual screening the freshness of fish and shrimp. Herein, we developed a chromogenic and fluorogenic sensor (RFCC) based on resorufin for sensing of biogenic amines including cadaverine and putrescine. RFCC underwent aminolysis with cadaverine or putrescine, displaying a remarkable fluorescence turn on response at 593 nm along with obvious color change from colorless to pink. RFCC was fabricated into test strips to sense cadaverine vapor, and the RGB value of test strips showed a good linear relationship with the concentration of cadaverine (0.5 - 8.2 × 10³ ppm). The RFCC tag was used to in situ screen the freshness of fish and shrimp according to obvious fluorescence change, and satisfactory results were achieved. Furthermore, this test strip was validated by total volatile base nitrogen (TVBN), providing a simple, low cost and portable tool to screen the freshness of fish and shrimp for consumers and suppliers without expensive instrumentation.

Determination of Freshness of Mackerel (Scomber japonicus) Using Shortwave Infrared Hyperspectral Imaging

Shortwave infrared (SWIR) hyperspectral imaging was applied to classify the freshness of mackerels. Total volatile basic nitrogen (TVB-N) and acid values, as chemical compounds related to the freshness of mackerels, were also analyzed to develop a prediction model of freshness by combining them with hyperspectral data. Fresh mackerels were divided into three groups according to storage periods (0, 24, and 48 h), and hyperspectral data were collected from the eyes and whole body, separately. The optimized classification accuracies were 81.68% using raw data from eyes and 90.14% using body data by multiple scatter correction (MSC) pretreatment. The prediction accuracy of TVB-N was 90.76%, and the acid value was 83.76%. These results indicate that hyperspectral imaging, as a nondestructive method, can be used to verify the freshness of mackerels and predict the chemical compounds related to the freshness.

A Novel Strategy for Accelerating Pumpable Ice Slurry Production with Ozone Micro-Nano Bubbles and Extending the Shelf Life of Larimichthys polyactis

In this study, a novel strategy for accelerating the production of pumpable ice slurry (PIS) by using ozone micro-nano bubbles (O₃-MNBs) was proposed. The effect of PIS containing sodium alginate (SA) and O₃-MNBs on the preservation of small yellow croaker (Larimichthys polyactis) was investigated. The results indicate that using SA solution containing O₃-MNBs instead of only SA solution resulted in quicker production of PIS by promoting ice nucleation and eliminating supercooling. The distribution and positive effect of O₃-MNBs as a nucleation agent on freezing characteristics were discussed. Microbial concentrations, pH, total volatile basic nitrogen, and thiobarbituric acid reactive substance content were also examined. Storage in novel PIS (containing O₃-MNBs) had higher performance than storage in flake ice or conventional PIS due to the strong bacteriostatic ability of O₃. Therefore, O₃-MNBs injection can be used as a novel method for PIS production and the preservation of fresh marine products.

Impact of Longkong Pericarp Extract on the Physicochemical Properties of Alginate-Based Edible Nanoparticle Coatings and Quality Maintenance of Shrimp (Penaeus monodon) during Refrigerated Storage

The objective of this study was to evaluate the impact of varying concentrations of longkong pericarp extract (LPE) on the physicochemical properties of alginate-based edible nanoparticle coatings (NP-ALG) on shrimp. For developing the nanoparticles, the alginate coating emulsion with different LPE concentrations (0.5, 1.0, and 1.5%) was ultrasonicated at 210 W with a frequency of 20 kHz for 10 min and a pulse duration of 1s on and 4 off. After that, the coating emulsion was separated into four treatments (T): T1: Coating solution containing basic ALG composition and without the addition of LPE or ultrasonication treatment; T2: ALG coating solution converted into nano-sized particles with ultrasonication and containing 0.5% LPE; T3: ALG coating solution converted into nano-sized particles with ultrasonication and containing 1.0% LPE; T4: ALG coating solution converted into nano-sized particles with ultrasonication and containing 1.5% LPE. A control (C) was also used, where distilled water was used instead of ALG coating. Before coating the shrimp, all the coating materials were tested for pH, viscosity, turbidity, whiteness index, particle size, and polydispersity index. The control samples had the highest pH and whiteness index and was followed by the lowest viscosity and turbidity (p < 0.05). Among the T1-T4 coating materials, T4 coating had higher turbidity, particle size, polydispersity index, but lower pH, viscosity, and whiteness index (p < 0.05). To study the quality and shelf-life of the shrimp, all coated shrimp samples were refrigerated at 4 °C for a period of 14 days. At 2-day intervals, physiochemical and microbial analyses were performed. The coated shrimp also had a lower increase in pH and weight loss over the storage period (p < 0.05). Coatings containing 1.5% LPE significantly reduced the polyphenol oxidase activity in the shrimp (p > 0.05). The addition of LPE to NP-ALG coatings demonstrated dose-dependent antioxidant activity against protein and lipid oxidation. The highest LPE concentration (1.5%) led to increased total and reactive sulfhydryl content, along with a significant decrease in carbonyl content, peroxide value, thiobarbituric acid reactive substances, p-anisidine, and totox values at the end of the storage period (p < 0.05). Additionally, NP-ALG-LPE coated shrimp samples exhibited an excellent antimicrobial property and significantly inhibited the growth of total viable count, lactic acid bacteria, Enterobacteriaceae, and psychotropic bacteria during storage. These results suggested that NP-ALG-LPE 1.5% coatings effectively maintained the quality as well as extended the shelf-life of shrimp during 14 days of refrigerated storage. Therefore, the use of nanoparticle-based LPE edible coating could be a new and effective way to maintain the quality of shrimp during prolonged storage.

Simultaneous Sensing of Ammonia and Temperatures Using A Dual-mode Freshness Indicator Based on Au/Cu Nanoclusters for Packaged Seafood

Seafood is highly perishable and monitoring its freshness this thus an important issue. For the first time, the current study developed a dual-mode freshness indicator based on d-penicillamine capped bimetallic gold/copper nanoclusters (DPA-Au/CuNCs) as a response probe for simultaneous monitoring of ammonia and temperatures to assess seafood freshness. Results indicated that the prepared DPA-Au/CuNCs have good sensitivity toward ammonia, with a limit of detection of 0.14 ppm. The indicator as a gas sensor for ammonia vapour detection exhibited highly recognizable fluorescence colour changes and the variations from white to yellow were observed with increasing storage temperature under natural light. For confirming its practical applications, the indicator was used to simultaneously monitor ammonia and temperatures during the storage of shrimp and fish, showing good potential for practical applications in evaluating seafood freshness for the food industry.

Comparative Evaluation of Physicochemical, Antioxidant, and Sensory Properties of Red Wine as Markers of Its Quality and Authenticity

The consumption of red wine by most wine drinkers has increased significantly because of the perceived health benefits which are linked to its inherent quality characteristics. In the quest to determine the conformity of Nigeria's domestic red wine quality with their international counterparts, the quality characteristics of domestic red wines produced in Nigeria were evaluated using foreign red wines as markers of wine quality and authenticity. Foreign and domestic red wines obtained in Nigeria were analyzed for physicochemical, antioxidant, and sensory properties using standard methods. Results showed that the domestic wines had significantly (p < 0.05) higher pH (4.03–4.16) and total sugar content (8.60–9.27%) while the foreign wines had significantly (p < 0.05) higher total titratable acidity (0.76–0.83%), Brix (6.98–8.04 g/100 g), alcohol (14.44–15.21% ABV), and polyphenol content (385.13–412.75 mg/L). Additionally, the domestic wines exhibited significantly (p < 0.05) lower antioxidant capacity compared to the foreign wines. Although the wines' hue angle (27.68°–41.46°) indicated a red colour spectrum in the visible region of the opponent colour chart, the total colour difference (ΔE) between foreign and domestic wines was significant. The sensory characteristics of the wines differed significantly as the panelist rating for overall acceptance ranged from 5.58 to 7.33. This research has provided valuable insight that the domestic wines studied showed a considerable level of authenticity and different levels of quality according to their varying concentration of organic acids, residual sugars, and phenolic compounds.

In-Vitro Study on the Antibacterial and Antioxidant Activity of Four Commercial Essential Oils and In-Situ Evaluation of Their Effect on Quality Deterioration of Pacific White Shrimp (Litopenaeus vannamei) during Cold Storage

The antioxidant and antibacterial properties of four essential oils (oregano essential oil (OEO), tea tree essential oil (TTEO), wild orange essential oil (WOEO), and clove leaf essential oil (CLEO)) were determined. The in-vitro experiment indicated that CLEO had the highest total phenolic content and DPPH scavenging activity, and OEO displayed the highest antibacterial effect, so they were applied to maintain the quality of shrimp for further study. In-situ study, the total viable counts of shrimp were inhibited from 9.05 log CFU/g to 8.18 and 8.34 log CFU/g by 2% of OEO and CLEO treated alone on 10 d. The melanosis ratio was also retarded from 38.16% to 28.98% and 26.35% by the two essential oils. The inhibitory effects of OEO and CLEO on the increase of PPO activity, weight loss, and TCA-soluble peptides, and the decreasing tendency of whiteness, the contents of myofibrillar and sarcoplasmic proteins were also founded. The samples treated with 1% OEO + 1% CLEO had better quality than those treated alone. Therefore, the combination of OEO and CLEO had a synergistic effect, which displayed the highest efficiency to prevent the melanosis, bacterial growth, and protein hydrolysis of shrimp.

Effects of High-Voltage Atmospheric Cold Plasma Treatment on Microbiological and Quality Characters of Tilapia Fillets

Cold plasma (CP) has become an alternative to conventional thermal processing of food products. In this study, the effect of cold plasma treatment time on the inactivation and quality of tilapia fillets was investigated. The surfaces of tilapia fillets were inoculated with Salmonella enteritis (S. enteritis), Listeria monocytogenes (L. monocytogenes), and a mixture of both before being treated with cold plasma at 70 kV for 0, 60, 120, 180, 240, and 300 s. With the extension of treatment time, the number of colonies on the surface of the fillets decreased gradually; after 300 s of cold plasma treatment, S. enteritis and L. monocytogenes populations were reduced by 2.34 log CFU/g and 1.69 log CFU/g, respectively, and the a* value and immobile water content decreased significantly (p < 0.05), while the free water content increased significantly (p < 0.05). TBARS value increased significantly (p < 0.05) to 1.83 mg MDA/kg for 300 s treatment. The carbonyl value and sulfhydryl value of sarcoplasmic protein significantly (p < 0.05) increased and decreased, respectively, as treatment time extension, while no significant changes were found in myofibrillar protein. No significant differences were observed in pH, b* value, elasticity, chewiness, thiol value, and TVB-N value. The results showed that cold plasma had an inactivation effect on tilapia fillets and could preserve their original safety indicators. It was concluded that CP treatment could be used as an effective non-thermal method to maintain the quality of tilapia fillets and extend their shelf-life.

Bioactive Compounds and Therapeutics from Fish: Revisiting Their Suitability in Functional Foods to Enhance Human Wellbeing

Global public awareness about fish-based diet and its health/nutritional benefits is on the rise. Fish nutritional profile projects promising bioactive and other compounds with innumerable health benefits for human wellbeing. As various reported researches involving fish/marine-derived molecules reveal promising attributes, and as the position of fish-based nutrients as nutraceuticals continue to strengthen, health challenges still confront communities worldwide, from cardiovascular disease, diabetes, and obesity to hypertension. Thus, further understanding of fish-based nutrient impact as functional foods remains crucial given the diverse prevailing compositional/nutraceutical merits. In this review, therefore, we provide important information regarding bioactive compounds and therapeutics obtained from fish, specific to the context of their suitability in functional foods to enhance human health. This contribution is hereby constructed as follows: (a) fish nutraceutical/therapeutic components, (b) constituents of fish-based nutrients and their suitability in functional foods, (c) fish antioxidant/bioactive compounds to help alleviate health conditions, (d) common human ailments alleviated by fish-based nutrients, and (e) role of fish in mental health and immune system. As increased fish consumption should be encouraged, the potential of the quality proteins, omega-3 fatty acids, and other compounds inherent in fish should steadily be harnessed.

Rapid quality deterioration of harpiosquillid mantis shrimp (Harpiosquilla raphidea) during iced storage

Changes in physicochemical, textural, microbial, and sensory quality of harpiosquillid mantis shrimp (Harpiosquilla raphidea) (HMS) during 10 days of iced storage were studied. Weight and cooking losses were increased during storage (p < 0.05). Drastic decrease in myosin heavy chain was found after 2 days of storage. Increases in total volatile basic nitrogen, trimethylamine, peroxide value, and thiobarbituric acid reactive substances with coincidentally augmented pH were found during the storage (p < 0.05). For microbiological analyses, total viable counts exceeded the limit at day 6. Melanosis score increased with a decreased L* value as storage time increased. Rapid decreases in hardness, springiness, cohesiveness, gumminess, and chewiness were associated with pasty and softened texture, which was supported by looser arrangement of muscle fiber along with gapping. This was reconfirmed by lowered shear force. Based on the quality evaluation, HMS could maintain the freshness and quality for not longer than 2 days in ice.

Quality improvement of shrimp ( Litopenaeus vannamei ) during refrigerated storage by application of Maillard peptides/water‐soluble chitosan coating

We investigated the effect of squid Maillard peptides (SMPs) on the shelf life and quality of shrimp for 20 days. Water‐soluble chitosan coatings incorporated with SMPs (SMPs + chitosan) were applied to shrimp under chilled conditions. Untreated samples were used as control, along with samples treated with water‐soluble chitosan and SMPs alone. The pH increase was observed in all samples, as well as increased total plate count, total volatile basic nitrogen, peroxide value, and thiobarbituric acid index. However, these indexes in the SMPs + chitosan group were lower than the other three groups, which suggested SMPs + chitosan might play a role in retarding quality loss of shrimp, and there might be a combined effect between water‐soluble chitosan and SMPs. Based on hardness, springiness, and sensory evaluation, shrimp coated with SMPs + chitosan was the best preserved, with a shelf life of 16 days but only 8–12 days for other samples. The present work demonstrates the effectiveness of SMPs + chitosan, offering a promising alternative to inhibit microbial growth and lipid oxidation on shrimps during refrigerated storage.

Zero-Waste Approach Applied to Pomegranates for Prolonging Fish Burger Shelf Life

In this study, the possibility of using whole pomegranate (juice, peel and seeds) according to the zero-waste approach, to prolong fresh fish shelf life, was evaluated. A preliminary antimicrobial in vitro test was carried out with peel and seeds as ground and re-ground powders. Then, the entire fruit, in the right proportions of juice and relative by-products as ground or re-ground powders, was added to fresh fish burger formulation to extend its shelf life. To this aim, a shelf-life test was performed on fortified fish products stored at 4 °C. Control samples were also tested for comparison. Specifically, the pH and microbiological and sensory quality of all the fish burgers were monitored during refrigerated storage for about 1 month. The results from the in vitro test clearly indicate that the peel is abundantly more effective than seeds on selected spoilage bacteria and that the ground peel powder is slightly more antimicrobial than the same re-ground powder. Results from the shelf-life test assessed that the control sample became unacceptable within a few days (about 3 days), while the samples with pomegranate juice and by-products maintained microbial stability for a longer time (2 or 3 weeks) (p < 0.05). The main microbiological problems are the proliferations of mesophilic and psychrotrophic bacteria, Pseudomonas spp. and Shewanella. The addition of pomegranate to the formulation allowed the fish spoilage to be controlled by at least 2 or 3 log cycles. In agreement with findings from the in vitro test, the best results from the microbiological point of view were found in fish burgers with juice, peel and seed ground powders. Furthermore, the addition of pomegranate was also appreciated from the sensorial point of view. In fact, products with pomegranate were prized for about 3 weeks for color, odor, appearance and texture of both raw and cooked products. Therefore, the current study reveals that the incorporation of the entire pomegranate, added in all parts according to the zero-waste concept, could promote a significant shelf-life extension of fish burgers, mainly due to the bioactive compounds present in fruit by-products, without changing the sensory quality.

Colorimetric detection of food freshness based on amine-responsive dopamine polymerization on gold nanoparticles

Biogenic amines (BAs) are not only well-known indicators for food freshness but can cause serious harm to the body after excessive consumption, which makes the determination of its content in food of great significance. In this work, a simple and convenient method for colorimetric detection of BAs was developed based on the sensitivity of the polymerization of dopamine to the presence of BAs on the surface of gold nanoparticles (AuNPs). Taking histamine as a representative, the system exhibited a distinct color change from wine red to black among the amine concentration of 1-100 μg/mL with the detection limit of 2.8 μg/mL. The detection system also exhibited sensitivity to other common kinds of BAs, such as putrescine, cadaverine, spermine, spermidine, tyramine, and tryptamine. Moreover, the proposed method showed encouraging performance in visual detection of the freshness of real samples, which provided a new approach for food quality and freshness evaluation.

Change Regularity of Taste and the Performance of Endogenous Proteases in Shrimp (Penaens vannamei) Head during Autolysis

This study evaluated the food safety and proximate composition of shrimp head (SH). Potentially toxic elements in SH were below European Union legislation limits. SH had a high content of tasting amino acids (sweet and umami amino acids was 57%) and a high content of functional amino acids (essential amino acids was 37%). Moreover, the changes of flavor and key umami molecules in SH were studied by sensory evaluation, electronic tongue, electronic nose, automated amino acid analyzer, and high performance liquid chromatography (HPLC). The results showed that the significant difference of flavor in SH happened during autolysis. SH with autolysis had the best umami taste at 6 h, which may result from the synergistic work of free amino acids and nucleotide related compounds. Additionally, the performance of endogenous proteases in SH was investigated to efficiently analyze autolysis. The optimum pH and temperature of endogenous proteases in SH were 7.5 and 50 °C, respectively. The autolysis of SH depends on two endogenous proteases (~50 kDa and ~75 kDa). These results suggest that the formation of flavor in SH during autolysis can be controlled, which could provide guidance for SH recycle. SH could consider as one of the food materials for producing condiments.

Functional properties of syrup from malted and unmalted rice of different varieties: A comparative study

The continued increase in Nigeria's rice production makes product diversification very fitting, even to underutilized indigenous/local varieties. Further, rice converted to malt can bring about useful products like syrup with enhanced characteristics. In this context, a comparative study involving some functional properties of syrup from malted and unmalted rice of different varieties was carried out. Syrup from either filtered or centrifuged starch hydrolysates of enzyme hydrolyzed rice (malted/unmalted) flours gave rise to filtered unmalted (FUHR), filtered malted (FMHR), centrifuged unmalted (CUHR), and centrifuged malted hydrolyzed rice (CMHR) groups. From these, functional properties, that is, pH, total soluble proteins (TSP), total dissolved solids (TDS), total solids (TS), dextrose equivalent (DE), titratable acidity (TA), apparent brix (°B), specific gravity (SG), syrup yield (SY), and some minerals [calcium (Ca), iron (Fe), magnesium (Mg), and zinc (Zn)] were determined. Results showed syrup from malted with significantly higher (P < 0.05) SY, Brix, pH, SG, TS, TDS, and TSP, but significantly lower (P < 0.05) TA, DE, and mineral contents (Ca, Zn, Fe, and Mg) over the unmalted group. Some significant interactions (P < 0.05) were found, between rice variety, treatment and separation method (TS, TDS, DE, Brix, SY, and Ca), rice variety and treatment (TSP, Zn, Mg, and Fe), as well as rice variety and separation method (TSP, pH). In addition, some positive and negative significant (P < 0.05) correlations between the studied functional properties were found. Overall, malting and processing methods can influence the functional properties of rice syrup-an acceptable specialty ingredient for brewing/beverage production. PRACTICAL APPLICATION: Through the application of exogenous enzymes, rice syrup has been successfully produced from locally bred/improved rice varieties commercially available in Nigeria. By comparing some functional properties of syrup from malted and/or unmalted rice, the current research provides useful evidence that locally available rice varieties are potential candidates for product diversification to the food/brewing, pharmaceuticals, and other industries, not only in Nigeria but also in the West Africa subregion.

Change of lipids in whelks (Neptunea arthritica cumingi Crosse and Neverita didyma) during cold storage

The objective of this study was to evaluate the change of lipids in two whelk samples during cold storage. Results showed that the peroxide value (PV) and thiobarbituric acid reactive substance (TBARS) increased while the percentage of polyunsaturated fatty acid decreased, indicating that lipid oxidation occurred. The cold storage significantly reduced the levels of triacylglycerol (TAG), polar lipid (PoL), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) but increased the levels of acid value (AV), free fatty acid (FFA) and monoacylglycerol, suggesting the hydrolysis of lipids. Moreover, the results showed that the lipoxygenase, acid lipase and phospholipase contributed to the hydrolysis and oxidation of lipids in the two whelks. Additionally, partial least squares discriminant analysis showed PC was positively correlated with PE, PoL and TAG, but negatively correlated with AV, FFA, PV and TBARS, indicating there is a close relationship between hydrolysis and oxidation of lipids.

Chemical Biopreservative Effects of Red Seaweed on the Shelf Life of Black Tiger Shrimp (Penaeus monodon)

Hypnea musciformis (HM) and Acanthophora muscoides (AM) red seaweeds were evaluated for their antioxidant properties and efficacy to extend the chemical shelf life of black tiger shrimp (Penaeus monodon) during 14-daystorage. Treated shrimp were soaked in five percent ethanolic solution with 500 µg/mL of AM or HM powder for 30 min. HM had more phenols and flavonoids, increased radical scavenging activity, and greater H₂O₂ reducing power than AM in vitro. Biochemical quality indicators were significantly higher in the control group, followed by HM- and AM-treated samples during storage. On day 14 of storage, controls contained significantly higher amounts of biogenic amines than HM- or AM-treated samples. The shelf life of chilled stored shrimp increased due to the presence of compounds of butylated hydroxytoluene, sulfurous acid, heptadecane, mono (2-ethylhexyl), and 1,2-propanediol found in AM extract and sulfurous acid and 1,2-propanediol found in HM extract. A control group was soaked in the same ethanolic solution as treated samples without algae powder for 30 min. Each group was kept ice-cold during the soaking period. The results obtained demonstrate the usefulness of two seaweed extracts, Hypnea musciformis and Acanthophora muscoides, combined with ice by decreasing the formation of toxic biogenic amines in shrimp, enhancing its shelf life during ice storage.

Quality evaluation of living and postmortem Chinese mitten crabs (Eriocheir sinensis)

Total volatile basic nitrogen (TVBN), biogenic amine, total viable count (TVC), volatile compounds, and sensory evaluation were conducted to assess the quality of Chinese Mitten Crabs (Eriocheir sinensis) at living, zero, 2, 5, 10, 15, and 24 hr postmortem. The sensory evaluation found a noticeable odor of spoilage becoming evident 10 hr postmortem. The TVBN value increased and then decreased as time increased, reaching 23.67 mg N/100 g at 24 hr postmortem. Although biogenic amines were detected at 5 hr postmortem, by 24 hr postmortem these had not reached dangerous levels of toxicity. The initial TVC (6.06 Log CFU/g) of the living crab samples was relatively high and climbed further postmortem, reaching 10.00 Log CFU/g 24 hr postmortem. Trimethylamine was detected in the living sample in belly meat and 2 hr postmortem in crab roe and reached 8.33 µg/g in the roe 24 hr postmortem. Indole was detected at 0 hr (belly meat) and 10 hr (crab roe) postmortem, but did not change significantly during the observation period. Sulfur-containing compounds were detected 5 hr after death and gradually increased over the observation period. Most indicators showed major changes at 5 hr and 10 hr postmortem. By 10 hr postmortem, the crab had entered the putrefaction stage and was thus no longer safe for consumption.

Quality Evaluation and Characterization of Specific Spoilage Organisms of Spanish Mackerel by High-Throughput Sequencing during 0 °C Cold Chain Logistics

Exploring the spoilage mechanism of Spanish mackerel is important to reduce the waste of Spanish mackerel and extend its shelf life. Cold chain logistics are commonly used to maintain the high quality and prolong the shelf life of aquatic products in circulation and storage. We assessed the sensory (body surface, odor, fish gills, fish elasticity, eyes, and overall assessment), chemical (total volatile base nitrogen (TVB-N), pH and 2-thiobarbituric acid (TBA)), and microbial characteristics (total viable counts (TVCs) and lactic acid bacteria) of Spanish mackerel combined with high-throughput sequencing at frequent intervals to determine their freshness and specific spoilage organisms (SSOs) during 0 °C cold chain logistics. Results showed that TVB-N, TBA, and TVCs correlated well (R2 > 0.90) with the sensory scores with prolonged circulation and storage time. The SSOs of Spanish mackerel were Proteobacteria in phylum and Pseudomonas in genus. The shelf life of mackerel under the 0 °C ice-stored cold chain system was approximately seven days, which is roughly three days longer compared with the traditional low-temperature storage method. These findings indicated that the freshness evaluation of Spanish mackerel in cold-chain circulation could be achieved by selecting appropriate chemical, microbial, and sensory indices. The study contributes to extend the shelf life of cold-chain Spanish mackerel by inhibiting the growth of dominant bacteria and provides a basis for the development of methods and tools to predict the shelf life of Spanish mackerel.