Search

In this study, the effects of different curing methods (static treatment, ultrasonic treatment, ultrasonic treatment combined with tumbling, vacuum tumbling and atmospheric pressure tumbling) on the textural properties, water retention and flavor quality of low-salt pre-prepared sea bass were investigated using texture analysis, scanning electron microscopy (SEM), liquid chromatography (LC) and gas chromatography-mass spectrometry (GC-MS). The results showed that tumbling alone and combined with ultrasonic treatment both significantly increased the marinade absorption rate and the mass transfer rate of sodium ion (P < 0.05), and the marinade absorption rate was 15.07% in the atmospheric pressure tumbling group, which was accompanied by reduced hardness and chewiness of fish meat. Organoleptic analysis showed that the fish treated by ultrasonic-assisted tumbling and tumbling was soft in texture, uniformly salty, and had less odor. In addition, both tumbling treatments significantly increased the total free amino acid content (P < 0.05), and the total free amino acid content was 7.395 mg/g in the atmospheric pressure tumbling group, which was about 1.24 times higher than that of the static treatment. A total of 65 volatile flavor compounds were detected across all treatment groups, among which, the contents of alcohols, esters and aromatic compounds were significantly higher (P < 0.05) in the tumbling treatment and ultrasonic-assisted tumbling groups than in the other treatment groups, suggesting that tumbling, irrespective of whether combined with ultrasonic or not, contributed to the formation of flavor substances. However, single tumbling marination showed poor water retention and water-holding capacity, and excessive tumbling might have adverse effects on fish texture. Therefore, ultrasonic-assisted tumbling was more suitable for the intensive processing of sea bass.

In this study, the effects of five common oxidative decontaminating agents (H2O2 solution, ClO2 solution, NaClO solution, ozonated water and slightly acidic electrolytic water) on the bacterial decontamination of tilapia fillets and their influence on the texture, color and myofibrillar protein (MP) oxidation in tilapia fillets were investigated. The results showed that a decontamination rate of 80% was attained by immersion in 1 500 mg/L H2O2 solution for 8 min, 200 mg/L ClO2 solution for 10 min, 200 mg/L NaClO solution for 10 min, 9 mg/L ozonated water for 10 min, or 30 mg/L slightly acidic electrolytic water for 20 min. Compared with the control group, treatment with decontaminating agents increased the hardness and L* value of tilapia fillets, decreased the a* value, MP content, total sulfhydryl group content, and raised the content of carbonyl groups and the amount of surface hydrophobic groups. The degree of protein denaturation in the slightly acidic electrolytic water and NaClO solution groups was the highest; the fluorescence intensity of MP was decreased after decontamination treatments, with the greatest decrease being found in the slightly acidic electrolytic water-treated group; the relative contents of α-helix and β-turn in MP were decreased, while the relative contents of β-fold and random coil were increased, with the most significant changes in the secondary structure of MP being observed in the slightly acidic electrolytic water-treated group (P < 0.05). MP underwent degradation to different extents, and the degradation degree of the slightly acidic electrolytic water group was higher than that of the other treatment groups. In summary, the oxidation of fish MP occurred to varying degrees after oxidative decontamination treatments, with slightly acidic electrolytic water treatment having the strongest oxidative effect.

In order to improve the drying rate and rehydration of tilapia meat, the freeze-drying characteristics and quality changes of blanched or steamed fish meat were analyzed. The effect of heat pretreatment on the quality of freeze-dried fish meat was elucidated by considering the denaturation degree of myofibrillar protein, water distribution and microstructural changes in fish meat during the drying process. The results showed that heat pretreatment could effectively improve the drying rate of tilapia meat, shortening the drying time by nine hours compared with the control group; blanching was more effective than steaming. The rehydration temperature range for tilapia meat was expanded by heat pretreatment, and good rehydration was observed at 50–80 ℃. The rehydration temperature for the control samples was 80 ℃, and the rehydration rate of the 10 min heat treatment group was more than 60%, indicating that the dried product can be rapidly rehydrated. The hardness of the rehydrated fish meat was similar to that of cooked fresh fish meat, and it had good mouthfeel. Heat pretreatment caused significant denaturation of myofibrillar protein and consequently changes in water distribution and a conspicuous increase in the peak area of transverse relaxation time T23, indicating that the increase in free water content after heat treatment is an important reason for the increase in freeze-drying rate. The experimental results can provide technical support for the development of ready-to-eat dried fish products that are suitable for rehydration.

In this study, the effect of fermentation with Bacillus subtilis B-2, a salt-tolerant strain capable of producing high yield of protease, on the microbial community and the contents of biogenic amines and amino acid nitrogen (AAN) during the fermentation of low-salt fish sauce. The results of high-throughput 16S rRNA gene sequencing showed that fermentation with B-2 reduced the richness and evenness of the microbial community, Bacillus was dominant throughout the fermentation process and the abundance of spoilage microorganisms significantly decreased. B-2 significantly inhibited the formation of histamine, putrescine, cadaverine, and tyramine, and their contents at the end of fermentation decreased by 25.9%, 35.6%, 23.6% and 9.3%, respectively, compared with those in naturally fermented fish sauce. The content of AAN in low-salt fish sauce was significantly improved by inoculated fermentation, reaching 1.23 g/100 mL after 15 days of fermentation, which was significantly higher than that of naturally fermented fish sauce (0.79 g/100 mL). The correlation network map showed that the decrease in the abundance of Brevibacterium, Dietzia, Paracoccus, Aequorivita, and Brachybacterium was the major reason for the decrease in microbial diversity at the late stage of fermentation of naturally fermented fish sauce. The abundance of Stenotrophomonas showed a significantly positive correlation with the contents of many biogenic amines in naturally fermented and B-2 fermented fish sauce, suggesting its important role in the formation of biogenic amines in low-salt fish sauce. Comparative analysis of the microbial community and quality attributes at the end of fermentation showed that the metabolism of B-2 was the main reason for the decrease in the species and abundance of spoilage microorganisms, the increase in AAN content, and the decrease in the contents of key biogenic amines. B. subtilis B-2 is expected to be developed as a special fermentation starter for fish sauce to improve the quality and safety of rapidly fermented low-salt fish sauce.

Summary: Lipid oxidation is a major concern in preserving fish and its products, as it affects their quality, shelf life, and consumer acceptance. Cold plasma technology has emerged as a promising method for extending the shelf life of perishable products, including fish. However, the impact of cold plasma on lipid oxidation remains uncertain, as studies have reported conflicting findings. This review provides an up‐to‐date overview of the effects of cold plasma treatment on lipid oxidation in fish and fish‐based products, synthesising existing literature in the field. A comprehensive analysis of factors such as plasma generation techniques, treatment parameters, fish species, and lipid composition is conducted to elucidate the observed discrepancies in outcomes. In conclusion, current research suggests that moderate oxidation does not have adverse effects on overall sensory quality and may even enhance the flavour of fish. The degree of oxidation can be controlled through plasma parameters, thereby improving the quality of fish and fish products. [ABSTRACT FROM AUTHOR]