The efficient extraction of high-quality fish oil with desirable sensory characteristics remains challenging owing to the limitations of conventional techniques such as Soxhlet extraction and enzymatic hydrolysis. In this study, we developed an ultrasound-assisted deep eutectic solvent method (DESM) for extracting bluefin tuna oil and compared its quality and flavor with oils extracted using traditional Soxhlet extraction (SEM) and enzymatic hydrolysis (EH) methods. Through process optimization, the optimal extraction conditions were determined as: ultrasonication temperature of 60 °C, duration of 60 min, power of 200 W, and a solid-to-liquid ratio of 1∶10 (W/W). Analyses using an electronic nose, electronic tongue, and volatile compound profiling indicated that the flavor profile of DESM-extracted fish oil was more diverse than that of SEM-extracted oil. Additionally, DESM-extracted oil contained compounds such as caryophyllene and 2-methyl-1-undecanol, which imparted a light greasy taste and a distinctive aroma. In contrast, undesirable odors, including greasy hexanal, strongly greasy 2-hexenal, and bitter almond-like benzaldehyde, were significantly reduced. However, these results reflect instrumental flavor differences rather than direct sensory preference. These findings suggest that DESM has potential for further development as a green fish oil extraction strategy, although additional validation of solvent residue control, storage stability, and sensory acceptability is still required.
This study investigated the effects of bran-layer removal on the nutritional composition, multi-scale molecular/crystalline structure, micromorphology, texture, thermal gelatinization, and rheological viscoelasticity of quinoa gels. With the elevation of degrees of milling (DOM, 0–35%), total starch content rose significantly from 57.66% to 80.22%, whereas the content of crude protein and crude lipid declined from 15.82% to 3.97% and 5.99% to 1.38%, respectively; meanwhile, amylose/amylopectin ratio grew steadily from 0.11 to 0.18. The water-holding capacity (WHC) peaked at 72.35% under DOM 19%; moderate bran stripping triggered adequate unfolding of native quinoa protein to build a continuous, compact gel three-dimensional network, improving gel elasticity, cohesiveness and resilience synchronously. At the microscale, scanning electron microscopy (SEM) verified that coarse irregular macropores transformed into tiny, evenly distributed network voids with rising DOM. At the molecular scale, Fourier-transform infrared (FTIR) spectroscopy exhibited a marked reduction in starch short-range ordered structure (quantified by the R₁₀₄₇/₁₀₂₂ peak ratio), corresponding to expanded amorphous starch domains; X-ray diffraction (XRD) further confirmed attenuated long-range starch crystallinity. Dynamic rheological frequency sweeps proved gel viscoelastic moduli (G′, G″) positively correlated with DOM and ambient temperature, and intermediate-milled samples possessed the most stable cross-linked network. Collectively, this work systematically elucidates the hierarchical multi-scale structural evolution law of quinoa starch-protein-fiber composite gels from molecular crystal, microscopic network to macroscopic functional properties, and provides targeted technical parameters for developing IDDSI-compliant soft gel foods for dysphagic populations.
To address the limitations of traditional chitosan (CS)-gelatin (GEL) films, this study developed composite films activated by a high internal phase Pickering emulsion (HIPPEs) stabilized by whey protein isolate fibrils-gallic acid-Fe3+ complexes (WPIFs-GA-Fe3+). The results indicated that, the water contact angle of pure chitosan/gelatin (CS/GEL) composite film was around 75.0°, which significantly increased to 80.4° to 87.7°, with the HIPPEs addition amounts varying from 1.0% to 2.0% (W/W), suggesting enhanced surface hydrophobicity. Water solubility (WS) decreased from 34% to as low as 24%, and moisture content dropped by 33% (from 36% to 24%) at a Fe3+/GA molar ratio of 0.5% and 2.0% addition level of HIPPEs, demonstrating improved water resistance. The glass transition temperature (Tg) of CS/GEL film was 146 °C, which was further increased, varying from 153 °C to 166.4 °C for the HIPPEs film. The incorporation of the WPIFs-GA-Fe3+ stabilized HIPPEs altered the hydrogen bonding and metal-phenolic coordination within the film matrix, thereby enhancing thermal stability and reducing water solubility. Besides, the water vapor permeability (WVP) and oxygen permeability (OP), and the mechanical properties of HIPPEs film were significantly improved as compared with CS/GEL composite film. This study demonstrates the huge potential of composite films functionalized by WPIFs-GA-Fe3+ stabilized HIPPEs as high-performance food packaging materials with tunable functional properties.
