Ailing Cao

Various volatile compounds are responsible for the odor changes in fish during storage. In this study, a coupled headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC-MS) analytical approach was applied to characterize the volatile compounds in large yellow croaker (Pseudosciaena crocea) during storage under three treatments: cold storage (CS), slurry ice (SI), and crushed ice (CI). A total of 24 volatile substances were identified, including aldehydes, ketones, and alcohols. Multivariate statistical analyses (PCA, PLS-DA, VIP, and cluster heatmap) revealed significant differences in volatile compounds between the treatment groups during storage, and 10 key volatiles along with 5 potential biomarker compounds were identified. The underlying mechanisms of volatile changes were further investigated by analyzing three key pathways: thermal reactions, lipid oxidation, and amino acid degradation. Notably, SI treatment better avoid volatile compound variation in large yellow croaker.

In this paper, tannic acid (TA) and Fe³⁺ were added to form a layer of metal-polyphenol network structure on the surface of the nanoparticles which were fabricated by zein and carbon quantum dots (CQDs) encapsulating Phlorotannins (PTN). pH-responsive nanoparticles were prepared successfully (zein-PTN-CQDs-Fe^Ⅲ). Further, the formation of composite nanoparticles was confirmed by a series of characterization methods. The zeta-potential and Fourier transform infrared spectroscopy data proved that electrostatic interaction and hydrogen bonding are dominant forces to form nanoparticles. The encapsulation efficiency (EE) revealed that metal-polyphenol network structure could improve the EE of PTN. Thermogravimetric analysis and differential scanning calorimetry experiment indicated the thermal stability of zein-PTN-CQDs-Fe^Ⅲ nanoparticles increased because of metal-polyphenol network structure. The pH-responsive nanoparticles greatly increased the release rate of active substances and achived targeted release.

In this research, ovalbumin (OVA) and sodium alginate (SA) were used as the materials to prepare an OVA–SA composite carrier, which protected and encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA) (OVA–SA, OVA–TA–SA, OVA–KAE–SA, and OVA–TA–KAE–SA). Results showed that the observation of small diffraction peaks in carriers proved the successful encapsulation of KAE/TA. The protein conformation of the composite nanoparticles changed. OVA–TA–SA composite nanoparticles had the highest α-helix content and the fewest random coils, so the protein structure of it had the strongest stability. OVA–TA–KAE–SA composite nanoparticles had the strongest system stability and thermal stability, which might be due to the synergistic effect of the two polyphenols, suggesting the encapsulation of KAE/TA increased the system stability and the thermal stability of OVA–SA composite nanoparticles. Additionally, the composite nanoparticles were endowed with antioxidant ability and antibacterial ability (against Staphylococcus aureus and Escherichia coli) in the order OVA–TA–SA > OVA–TA–KAE–SA > OVA–KAE–SA based on the difference in antibacterial diameter (D, mm) and square (S, mm²), indicating that polyphenols enhanced the antibacterial and antioxidant ability of OVA–SA composite nanoparticles, and the enhancement effect of TA was stronger than that of KAE. These results provide a theoretical basis for the application of OVA–SA composite nanoparticles in the delivery of bioactive compounds.

Active films with essential oils have attracted more attention in recent years. In order to improve the solubility and stability of ginger essential oil (GEO) in film forming solutions, GEO coarse emulsion and nanoemulsions were prepared named CGEO (z‐average = 799.53 nm), NGEO‐1 (z‐average = 114.71 nm) and NGEO‐2 (z‐average = 59.30 nm), respectively. And the effect of concentration (0.5% and 1.0% v/v) and particle sizes of GEO emulsions on the physiochemical and preservation properties of fish sarcoplasmic protein and chitosan blend based edible films were studied in this study. The elongation at break significantly (p < .05) increased after adding GEO emulsions, and the light transmittance, water vapor permeability and water solubility were the lowest when NGEO‐2 was incorporated into films. The antioxidant and antimicrobial activities of films were concentration‐dependent. Furthermore, all the films were applied into packaging red sea breams fillets, and the results of total viable counts, pH and thiobarbituric acid demonstrated that SP‐CH films with GEO emulsions, especially nanoemulsions obviously prolonged the shelf‐life of fillets during 4°C.Practical Applications: In recent years, the research about incorporating essential oils into edible films to prepare active edible films due to their antimicrobial and antioxidant properties have been more documented. In this study, fish sarcoplasmic protein and chitosan were chosen as film‐forming materials to prepare active films with ginger essential oil emulsions. The physicochemical, mechanical, optical properties of films showed that the films have the basic characteristics as food packaging materials. The releasing and antioxidant property of films indicated that the active films have a potential application in packaging food which was easy oxidized. The basic properties of films combined with oxidation indicators (total viable count, pH and thiobarbituric acid reactive substances) would provide the scientific basis for developing active films and their application for food packaging, such as seafood, meat, fruits and vegetables.