Raman spectroscopy and low‐field nuclear magnetic resonance used to monitor the relationship between protein conformation and water retention in the formation for process of gel

Separation and quantification of tire and road wear particles in road dust samples: Bonded-sulfur as a novel marker

Tire road wear particles (TRWPs) are a large source of microplastics in the environment, while the quantification of TRWPs is still challenging due to the complex interferences and the uncertainties and inconsistencies among different methods. This study developed a TRWPs quantification method using optimized pretreatments and bonded-sulfur as marker. Road dust samples (n = 48) were collected, pretreatments including density separation, digestion and extraction were optimized to remove interferences of the bonded-sulfur (minerals, sulfur-containing proteins, hydrosoluble/hydrophobic sulfur-containing substances). Presence of TRWPs in the samples was confirmed by microscopy and scanning electron microscopyenergy dispersive spectrometry. Bonded-sulfur in the samples were quantified by inductively coupled plasmamass spectrometry (ICPMS). Additionally, bonded-sulfur in tire wear particles (TWPs) abraded from tires of top 10 best-selling brands were measured to calculate conversion factor (1.1 ×104 μg/g) for the quantification of TRWPs in real samples. TRWPs contents were 5.40 × 104 μg/g11.02 × 104 μg/g and 2.36 × 104 μg/g5.30 × 104 μg/g in samples from heavy and light traffic roads, respectively. The method provided better recoveries (88-107%, n = 18) and repeatability (RSD=2.0-7.9%, n = 3) compared to methods using rubber, benzothiazole and organic zinc as markers. Furthermore, stability of the bonded-sulfur was validated by Raman and ICPMS. Thus, this accurate and stable quantification method could promote research on TRWPs.

Insight into the correlations among rheological behaviour, protein molecular structure and 3D printability during the processing of surimi from golden pompano (Trachinotus ovatus)

To investigate the 3D printability of surimi from golden pompano, the rheological properties, protein molecular structure, and 3D printability of food inks from every step of surimi processing were measured, and their correlations were analysed. The results showed that surimi from chopping (surimi-C), chopping with salt (surimi-CS) and setting (surimi-S) were suitable for 3D printing, among which surimi-CS had the best shape fidelity. The clustering analysis of variables revealed that the yield stress and A_F could be used as indexes to characterize extrusion and deposition behaviour of surimi, respectively. The accuracy of 3D printing was affected by the extrusion property of the food ink, which was controlled by the ionic bond content. The stability of 3D printing was affected by the self-supporting capacity of the food ink, which was controlled by the hydrogen bond and hydrophobic interaction contents. The results provided theoretical guidance for developing 3D printing of surimi ingredients.

Saltiness perception enhancement of fish meat treated by microwave: The significance of conformational characteristics, water and sodium mobility

A saltiness perception enhancement method of grass carp meat conducted by microwave heating was investigated. Ion chromatographic results demonstrated that all samples had the same sodium level retained in matrices after being treated by water bath (WBV) and microwave with different power of 2.5, 7.5, 10, and 12.5 W/g (MWV). However, the meat treated by microwave exhibited a higher salty intensity than that of WBV, particularly MWV-10 W/g and MWV-12.5 W/g. The enhanced saltiness perception of meat treated by microwave was attributed to the facilitated water and sodium mobility demonstrated by low field-NMR and pulse-field-gradient stimulated echo (PFG-STE) ²³Na NMR experiments. Furthermore, the enhancement was also related to the formation of microstructure favorable for sodium diffusion, originating from the insufficient denaturation and less exposure of hydrophobic groups of proteins induced by microwave heating. Therefore, microwave heating has the potential to enhance the saltiness perception of meat in the food industry.