Development of novel fermented stinky sea bass and analysis of its taste active compounds, flavor compounds, and quality

Analysis of changes in volatile compounds and evolution in free fatty acids, free amino acids, nucleotides, and microbial diversity in tilapia (Oreochromis mossambicus) fillets during cold storage

BACKGROUND

Aquatic products are rich in nutrients and unique in flavor, and are popular among the public. However, aquatic products are extremely susceptible to quality degradation during storage, of which odor deterioration is the most obvious and influential aspect. Odor deterioration in aquatic products is widespread and severely affects overall flavor and quality. In this study, odor deterioration and flavor-related quality degradation of tilapia during cold storage are discussed, focusing on the changes in volatile compounds and the evolution of free fatty acids (FFAs), free amino acids (FAAs), nucleotides, and microbial diversity.

RESULTS

A total of 63 volatile compounds were detected by gas chromatography-mass spectrometry, including 11 hydrocarbons, 10 alcohols, 6 aldehydes, 8 ketones, 6 esters, 9 aromatics, 3 phenols, and 10 other compounds. Microbial diversity analysis revealed that Acinetobacter, Psychrobacter, Vagococcus, and Myroides were the main dominant species of tilapia at the end of cold storage and predicted that microorganisms could influence the flavor of tilapia by participating in important metabolic pathways. Meanwhile, the evolution of FFAs, FAAs, and nucleotides also had a significant impact on odor deterioration, as evidenced by the contribution of unsaturated fatty acids (such as oleic acid and linoleic acid), Lys, and off-flavor nucleotides (HxR and Hx) to the undesirable flavor. Oxidation of oleic acid and linoleic acid resulted in changes in aldehydes, with Lys, HxR, and Hx being key flavor precursors and off-flavor contributors.

CONCLUSION

This study contributes to a comprehensive overview of odor deterioration and the evolution of flavor-related quality in tilapia during cold storage, providing new insights into the regulation of overall flavor and quality. © 2023 Society of Chemical Industry.

Changes in Flavor-Related Biomarkers in Pacific Oysters (Crassostrea gigas) Following Microplastic Exposure

Microplastics have been an emerging threat to filtering species and the ingestion and impacts of microplastics on oysters are a cause for concern. However, much remains unknown about the effects of microplastics on flavor-related biomarkers in oysters. Herein, a laboratory microplastic exposure with concentrations of 1, 10, and 100 mg/L for 15 days was performed to investigate the impacts of microplastics on the flavor parameters of oysters. Exposure to microplastics changed the odor characteristics of oysters. Microplastic exposure had minor effects on the fatty acid composition; however, significant alterations in free amino acids and nucleotides were observed under the 1 and 10 mg/L exposure groups, respectively. The overall results indicated 10 mg/L of microplastic exposure significantly increased the equivalent umami value of oysters. These findings stressed the effects of microplastics on oysters and would be an important reference for the assessment of the potential risks associated with microplastics in marine edible species.

Ultrasonic treatment treated sea bass myofibrillar proteins in low-salt solution: Emphasizing the changes on conformation structure, oxidation sites, and emulsifying properties

The physiochemical properties, structure characteristics, oxidation, and emulsifying properties of myofibrillar proteins (MPs) in low salt solution after treated by the ultrasound were investigated. The solubility, mean diameters, sulfhydryl content, and carbonyl contents of MPs after ultrasonic treatment increased, while the turbidity decreased. The surface hydrophobicity of MPs with 200 W-600 W treatment increased, but decreased at 800 W treatment. The circular dichroism analysis revealed that α-helix content increased, while β-sheet and random coil content decreased after ultrasonic treatment. Fluorescence spectroscopy indicated the fluorescence intensities of MPs were increased after ultrasonic treatment. SDS-PAGE results showed more protein polymers due to myosin heavy chain (MHC) aggregation via disulfide bonds. Based on LC-MS/MS result, the myosin heavy chain was susceptible to oxidation, with monooxidation being the main oxidative modification. Finally, the emulsions stabilized by ultrasonically treated MPs, especially those treated at 800 W, exhibited decreased particle size, improved uniformity, and enhanced stability.