Influence of Refrigerated Storage on Water Status, Protein Oxidation, Microstructure, and Physicochemical Qualities of Atlantic Mackerel (Scomber scombrus)

Evaluation of White Grape Marc Extract as an Additive to Extend the Shelf-Life of Fish Fillets

In this study, an extract of white grape marc (GME), a by-product obtained during the winemaking process, was applied to the surface of gilthead seabream (Sparus aurata) fillets, which were then stored under refrigeration (4 °C) for a period of 14 days. The effects of GME were compared with those of ascorbic acid (one of the few additives authorized for fresh fish in the EU) and distilled water (as a control batch). Samples were taken at 1, 2, 4, 7, 9, 11, and 14 days postmortem (dpm) cold storage, and several objective quality parameters were measured (instrumental color, pH, water holding capacity, texture profile analysis-TPA, lipid oxidation, and microbial spoilage). The results showed that the grape extract significantly improved several of the parameters studied, not only compared to the control batch, but even compared to the ascorbic acid batch. Thus, GME slowed down the proliferation of psychrophilic bacteria, prevented the oxidation of muscle lipids, and even improved the firmness of the fillets compared to the other two experimental groups. On the other hand, minor effects on color, pH, or water retention capacity were observed. In the context of the scarcity of approved food additives for fresh fish in the EU and the strong consumer rejection of synthetic substances for this purpose, this grape extract could well represent a viable alternative. In addition to its natural origin, the use of GME as a food additive could also contribute to the valorization of winery by-products as part of a circular bioeconomy strategy.

Rice bran oil-in-water emulsion stabilized by Amur catfish myofibrillar protein: Characteristics and its application in surimi gels

The objective of this investigation was to isolate amur catfish myofibrillar protein (AMP), emulsify it with rice bran oil, and assess its application in the silver carp surimi gel. The proportion and addition of AMP/rice bran oil emulsion on the gel properties were compared. The emulsion stabilized by 3 % AMP was stable when an oil/water ratio of 0.70 and 0.75 was employed, as evidenced by its appearance, microstructure, and rheological characteristics. The L*, a* and whiteness values of gels observably elevated when the emulsion blended (p < 0.05). The mechanical capacities (texture and rheology indicators) of surimi gels were dramatically improved with 5 % emulsion added (p < 0.05). However, the addition of excessive emulsion (up to 15 %) impeded the formation of surimi protein network and lowered water retention ability of surimi gels. Moreover, 5 % emulsion was distributed uniformly throughout the gel matrix, giving rise to the development of a dense and uniform network with high water binding capacity. Furthermore, the study on protein solubility expressed that the addition of the emulsion facilitated protein-protein interactions in surimi gels. In summary, the addition of 5 % AMP stabilized rice bran oil emulsion could yield a stronger surimi gel with increased whiteness. The resulting gels could serve as healthy fat-rich surimi-based products.

The quality of frozen-thawed Atlantic salmon (Salmo salar L.) fillets as affected by sub-chilling before freezing

BACKGROUND

To maintain the quality of frozen Atlantic salmon after thawing and highlight the potential for moving from air fright to boat for long-distance export, a study was designed to investigate the effects of sub-chilling before rapid freezing on the quality of thawed fillets. Atlantic salmon chilled on wet ice before filleting and freezing was used as a control for the experimental factor chilling, whereas fresh fillets were used for the frozen-thawed samples.

RESULTS

The pre-freezing chilling method interacted with the storage protocol and significantly affected the product. For fresh stored fillets, sub-chilling improved the microbiological and textural stability and degradation of proteins. After 1 month of frozen storage, sub-chilled fillets gave better color and textural properties, less adenosine triphosphate degradation and protein denaturation. In addition, sub-chilled 4-month-frozen fillets also showed improved microbial stability compared to those initially chilled with ice before frozen storage. Quality was lost as a function of storage. Fresh fillets generally had higher bacterial counts, surface breaking force, firmness, hue and contents of inosine monophosphate, and lower drip loss and inosine (HxR) levels than those stored frozen-thawed. Moreover, 4-month-frozen fillets had higher HxR levels and lower psychrotrophic viable count growth than those that were frozen for 1 month. The time fillets were stored frozen did not profoundly affect their quality.

CONCLUSION

It is concluded that a frozen product might be competitive with a fresh product when sub-chilling is performed before freezing, especially when including the environmental benefits of frozen export by boat rather than air freight. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Correlation analysis of phosphorylation of myofibrillar protein and muscle quality of tilapia during storage in ice

In this study, the correlation between protein phosphorylation and deterioration in the quality of tilapia during storage in ice was examined by assessing changes in texture, water-holding capacity (WHC), and biochemical characteristics of myofibrillar protein throughout 7 days of storage. The hardness significantly decreased from 471.50 to 252.17 g, whereas cooking and drip losses significantly increased from 26.5% to 32.6% and 2.9% to 9.1%, respectively (P < 0.05). Myofibril fragmentation increased, while myofibrillar protein sulfhydryl content and Ca2+-ATPase activity decreased from 119.33 to 89.29 μmol/g prot and 0.85 to 0.46 μmolPi/mg prot/h, respectively (P < 0.05). Correlation analysis revealed that the myofibrillar protein phosphorylation level was positively correlated with hardness and Ca2+-ATPase activity but negatively correlated with WHC. Myofibrillar protein phosphorylation affects muscle contraction by influencing the dissociation of actomyosin, thereby regulating hardness and WHC. This study provides novel insights for the establishment of quality control strategies for tilapia storage based on protein phosphorylation.

Physicochemical parameters and nutritional profile of back and abdomen muscle of fresh golden pompano (Trachinotus ovatus) and hybrid grouper (Epinephelus lanceolatus × Epinephelus fuscoguttatus)

Golden pompano (Trachinotus ovatus) and hybrid grouper (Epinephelus lanceolatus × Epinephelus fuscoguttatus) has widely been distributed in China and Southeast Asian countries with great commercial importance. In this study, the nutritional profiles, chemical and physical parameters of back and abdomen muscles were determined. Significantly different (p < .05) proximate compositions were found in two fish muscles. The contents of water-soluble protein, salt-soluble protein, and non-nitrogenous protein were higher in the golden pompano while salt-insoluble proteins were higher in the hybrid grouper. The main minerals found were K (3700.56-4495.57 μg/g) followed by P > Na > Mg > and Ca, respectively. Fatty acids contents consisted of polyunsaturated fatty acids ranging from 29.40% to 43.09% and saturated fatty acids 28.33% to 39.61%. The muscles were rich in n-3 PUFAs with n-6/n-3 ratio of 1.36%-2.96% in the back and abdomen. On the other hand, total amino acid and non-essential amino acid contents were found higher in the hybrid grouper while essential amino acid and delicious amino acid contents were higher in the golden pompano. Glutamic acid was the most predominant amino acid. The amino acid scores (AAS) of six amino acids were close to 1.00, whereas lysine showed the highest AAS while tryptophan was the most limited essential amino acid in all muscles, respectively. These results indicated golden pompano and hybrid grouper exhibited a varied nutritional composition and offered a good nutritional profile.

Improving the texture properties and protein thermal stability of Antarctic krill (Euphausia superba) by L-lysine marination

BACKGROUND

The quality deterioration of Antarctic krill (Euphausia superba) after thermal processing limits its industrial application. This study sought to improve the texture characteristics of Antarctic krill after heat treatment through pre-soaking using l-lysine (Lys) solution and sodium tripolyphosphate (STPP). Moreover, the effects of Lys on heat-treated Antarctic krill were explored.

RESULTS

Lys significantly reduced the cooking loss and improved the texture characteristics of Antarctic krill during heat treatment. The low-field nuclear magnetic resonance results showed that Lys reduced the water loss of Antarctic krill during heat treatment. Additionally, the surface hydrophobicity, Fourier transform infrared spectroscopy, and endogenous fluorescence spectroscopy results showed that Lys could inhibit the structural damage of Antarctic krill protein under the thermal denaturation condition and enhance the thermal stability of the protein. The scanning electron microscopy results showed that Lys could protect the structural integrity of Antarctic krill muscle fibers during heat treatment.

CONCLUSION

The cooking loss in the Lys added groups was better than the sodium tripolyphosphate added group, and 2.0% Lys solution could minimize the cooking loss of Antarctic krill. The secondary and tertiary structures of the Antarctic krill protein were actively protected by Lys during heat treatment. Overall, the study will provide insights into the application of Lys in the food industry as a natural additive and an alternative to phosphate. © 2021 Society of Chemical Industry.

The Influence of Hypothermia Hibernation Combined with CO2 Anesthesia on Life and Storage Quality of Large Yellow Croaker (Pseudosciaena crocea)

We explore the feasibility of the long-term transportation of live large yellow croakers (Pseudosciaena crocea) using the combined method of CO₂ anesthesia and hypothermia hibernation, and its effect on the quality of recovered fish stored at 4 °C. Fish treated with CO₂ anesthesia at a 2 ppm/s aeration rate were cooled at 3 °C/h to hibernate survived for 36 h at 8 °C in seawater. This method resulted in better survival rates and time, and a lower operational time than hypothermia hibernation or CO₂ anesthesia methods. The results of a blood analysis indicated that the stress experienced by the fish during hibernation was mitigated, but existent after recovery. The drip loss rate of the ordinary muscle of hibernated fish was significantly different from that of the control group at 4 °C, but there was no significant difference in the pH, lactic acid content, and color during early storage. Furthermore, hibernation did not affect springiness and chewiness. Thus, the combination of CO₂ anesthesia and hibernation may improve the survival and operation efficiency of fish in long-term transportation. However, this method affects the quality of fish after long-term storage. Thus, hibernated fish should be consumed after appropriate domestication or immediately after recovery.

Quality Characteristics and Moisture Mobility of Giant Salamander (Andrias davidianus) Jerky during Roasting Process

Quality attributes and water mobility of giant salamander jerkies (GSJs) during roasting process (160°C, for 0, 20, 40, 60, and 80 min) were investigated. The results showed that $a^{\ast },b^{\ast }$ values and shear force increased of GSJs roasting from 20 to 80 min, while $L^{\ast }$ , yield, and moisture content decreased significantly ( $p<0.05$ ). Sensory assessment showed that GSJs at a roasting time of 40–60 min had higher scores. GSJs contained great amount of healthy unsaturated fatty acids (including DHA and EPA), and the total amino acids and essential amino acids were among 59.33–71.77 g·100 g−1 and 25.94–31.40 g·100 g−1, respectively. The mobility of the immobilized moisture and free moisture were shrunk dramatically during roasting. The proton density weighted images also exhibited the moisture shrinkage during roasting. In addition, T22 and T23 were positively correlated with MRI signal, moisture content, and yield of GSJs, but negatively correlated with shear force and overall acceptability, respectively. Thus, in view of various quality attributes and sensory evaluation, a roasting time of 40–60 min was favored for nutritive GSJs production. LF-NMR and MRI might be employed to profile the quality characteristics during roasting as a rapid and nondestructive analytical tool.