Composition-antifreeze property relationships of gelatin and the corresponding mechanisms.

The inherent functional fractions (gelation and ice-affinitive fractions) of gelatin enable it as a promising cryoprotectant alternative. However, the composition-antifreeze property relationships of gelatin remain to be investigated. In this study, the HW-PSG and LW-PSG fractions of gelatin from fish scales were obtained, according to the critical gelation conditions and ice-binding measurements, respectively. Thermal hysteresis (THA) value, associated with ice nucleation, of LW-PSG was higher than that of HW-PSG. Besides, the relatively low-sized ice crystals (210-550 µm2) indicated that HW-PSG showed strong ice recrystallization inhibition (IRI) ability, compared to other groups. These results suggested that LW-PSG inhibited ice nucleation, while HW-PSG displayed the strong IRI ability. Furthermore, the antifreeze mechanisms were clarified through IRI measurements and molecular dynamics simulation. The minimum size of ice crystals was found for HW-PSG gels with dense microstructure, suggesting the HW-PSG retarded the growth of ice crystals by restricting the migration and phase transformation of water molecules. The hydrogen bond interactions between the ice crystal surface and ASN1294 and PRO1433 residues of LW-PSG, and hydrophobic interactions contributed to inhibiting the nucleation of ice crystals. This study provided some references to further enhance antifreeze performance of gelatin by modulating fragment composition.

Improving the texture attributes of squid meat (sthenoteuthis oualaniensis) with slight oxidative and phosphate curing treatments.

This study aimed to improve the pasty texture of squid meat by oxidative and phosphate curing (OPC) treatment, and elucidate the underlying mechanism. The shear force, springiness, weight gain, water-holding capacity (WHC), color and sensory evaluation of squid meat samples treated with a mild OPC approach (OPC_2, 10 mM H2O2 solution with complex phosphate solution) were significantly improved. However, the samples subjected to over-oxidized (20 and 30 mM H2O2 solution with complex phosphate solution) treatment did not obtain favorable outcomes. Microstructure analysis revealed that muscle fibers aggregated after moderate OPC treatments, leading to an increased spacing between muscle fiber bundles. This gap facilitated a more uniform distribution and restriction of water, according to low-field nuclear magnetic resonance (LF-NMR) results. The results from in vitro simulated oxidation of myofibrillar proteins (MPs) demonstrated that increased H2O2 led to formation of carbonyl groups and decreased sulfhydryl groups, and even secondary structure changes, according to fourier transform infrared spectroscopy (FT-IR). Particle size, zeta potential and sodium dodecyl sulfate-polyacryl amide gel electrophoresis (SDS-PAGE) results showed that oxidation caused protein aggregation into larger molecules. This study presents a novel approach to improve pasty texture of squid meat.

Plasma-Membrane-Localized Transporter NREET1 is Responsible for Rare Earth Element Uptake in Hyperaccumulator Dicranopteris linearis.

Rare earth elements (REEs) are critical for numerous modern technologies, and demand is increasing globally; however, production steps are resource-intensive and environmentally damaging. Some plant species are able to hyperaccumulate REEs, and understanding the biology behind this phenomenon could play a pivotal role in developing more environmentally friendly REE recovery technologies. Here, we identified a REE transporter NRAMP REE Transporter 1 (NREET1) from the REE hyperaccumulator fern Dicranopteris linearis. Although NREET1 belongs to the natural resistance-associated macrophage protein (NRAMP) family, it shares a low similarity with other NRAMP members. When expressed in yeast, NREET1 exhibited REE transport capacity, but it could not transport divalent metals, such as zinc, nickel, manganese, or iron. NREET1 is mainly expressed in D. linearis roots and predominantly localized in the plasma membrane. Expression studies in Arabidopsis thaliana revealed that NREET1 functions as a transporter mediating REE uptake and transfer from root cell walls into the cytoplasm. Moreover, NREET1 has a higher affinity for transporting light REEs compared to heavy REEs, which is consistent to the preferential enrichment of light REEs in field-grown D. linearis. We therefore conclude that NREET1 may play an important role in the uptake and consequently hyperaccumulation of REEs in D. linearis. These findings lay the foundation for the use of synthetic biology techniques to design and produce sustainable, plant-based REE recovery systems.

A comparative study on the taste quality of Mytilus coruscus under different shucking treatments.

Shucking is an indispensable step in the preparation of cooked mussel products, as it facilitates the detachment of meat from the shell. In this study, we comprehensively investigated the effects of boiling, steaming, and microwaving on taste constituents in half-cooked mussel meat. Two-dimensional correlation spectroscopy revealed the key differential taste components of the different shucking groups. Structural equation modeling (SEM) indicated the positive effects of saltiness and bitterness on umami taste, while sweetness and sourness had negative effects on umami taste in half-cooked mussel meat. Furthermore, Glu, Asp, Ala, Arg, betaine, malic acid, succinic acid, glycogen, Cl-, Na+, K+, and PO3- 4 were quantitatively determined as the main taste compounds. The steaming shelling group had the most enriched taste components, with the highest equivalent umami concentration compared to the other shelling groups. Hence, steaming shucking may be favored due to abundant tastes and nutrients.

Mechanisms of alkali pH-shifted colour changes in squid (Uroteuthis edulis) subjected to frozen storage.

The skin discoloration of squid subjected to frozen storage negatively affects market price. In this study, various alkali treatments were investigated for effects on red granules and yellow pigments of squid skin and corresponding mechanisms were investigated at the tissue, cellular and molecular level. A significant colour improvement was observed when subjected to a pH 12 treatment, supported by decreased Δb* and increased Δa* values. Neither lower nor harsher alkali treatments than pH 12 can not obtain such results. HE staining and the UV-vis spectrum suggest that the improved red colour in skin was ascribed to the release of red pigment granules from damaged chromatophores by alkaline treatment and the release of red pigments in alkaline aqueous solutions from granules. However, based on TEM and particle size analysis, an excessive alkali treatment of pH 13 would degrade granules into smaller particles. The degradation of yellowness pigments indicated high sensitivity to alkali environments according to HPLC results. This study provides a valuable reference for improving the colour appearance of squid skin subjected to frozen storage.

Gel-type emulsified muscle products: Mechanisms, affecting factors, and applications.

The gel-type emulsified muscle products improve fatty acid composition, maintain the oxidative stability, and achieve a better sensory acceptability. This review emphasizes the stabilization mechanisms of these emulsified muscle products. In particular, factors associated with the stability of the emulsified muscle systems are outlined, including the processing conditions (pH and heating), lipids, and emulsifiers. Besides, some novel systems are further introduced, including the Pickering emulsions and organogels, due to their great potential in stabilizing emulsified gels. Moreover, the promising prospects of emulsion muscle products such as improved gel properties, oxidative stability, freeze-thaw stability, fat replacement, and nutraceutical encapsulation were elaborated. This review comprehensively illustrates the considerations on developing gel-type emulsified products and provides inspiration for the rational design of emulsified muscle formulations with both oxidatively stable and organoleptically acceptable performance.

Emulsion Surimi Gel with Tunable Gel Properties and Improved Thermal Stability by Modulating Oil Types and Emulsification Degree.

High resistance to heating treatments is a prerequisite for ready-to-eat (RTE) surimi products. In this study, emulsion-formulated surimi gels were prepared, and the effects of oil types and emulsification degrees on the thermal stability of surimi gel were investigated. The results showed the gel properties of surimi gels were modulated by oil types and emulsification degrees. In detail, the rising pre-emulsification ratio caused the increase of the emulsifying activity index (EAI) and decrease of emulsifying stability index (ESI) for both emulsions. The larger droplet sizes of perilla seed oil than soybean oil may be responsible for their emulsifying stability difference. The gel strength, water retention, dynamic modulus and texture properties of both kinds of surimi gels displayed a firstly increased and then decreased tendency with the rising pre-emulsification ratios. The peak values were obtained as perilla seed oil emulsion with emulsification ratio of 20% group (P1) and soybean oil emulsion with emulsification ratio of 40% group (S2), respectively. Anyway, all emulsion gels showed higher thermal stability than the control group regardless of oil types. Similar curves were also obtained for the changes of hydrogen bond, ionic bond and hydrophobic interactions. Overall, perilla seed oil emulsion with emulsification ratio of 20% (P1 group) contributed to the improved thermal stability of surimi gels.

Rapid and non-destructive freshness evaluation of squid by FTIR coupled with chemometric techniques.

BACKGROUND: Freshness is an important quality of squid with respect to determining the market price. The methods of evaluation of freshness fail to be widely used as a result of the lack of rapidity and quantitation. In the present study, a rapid and non-destructive quantification of squid freshness by Fourier transform infrared spectroscopy (FTIR) spectra combined with chemometric techniques was performed. RESULTS: The relatively linear content change of trimethylamine (TMA-N) and dimethylamine (DMA-N) of squid during storage at 4 °C indicated their feasibility as a freshness indicator, as also confirmed by sensory evaluation. The spectral changes were mainly caused by the degradation of proteins and the production of amines by two-dimensional infrared correlation spectroscopy, among which TMA-N, DMA-N and putrescine were the main amines. The successive projections algorithm (SPA) was employed to select the sensitive wavenumbers to freshness for modeling prediction including partial least-squares regression, support vector regression (SVR) and back-propagation artificial neural network. Generally, the SPA-SVR model of the selected characteristic wavenumber showed a higher prediction accuracy for DMA-N (R2 P  = 0.951; RMSEP  = 0.218), whereas both SPA-SVR (R2 P  = 0.929; RMSEP  = 2.602) and Full-SVR (R2 P  = 0.941; RMSEP  = 2.492) models had a higher predictive ability of TMA-N. CONCLUSION: The results of the present study demonstrate that FTIR spectroscopy coupled with multivariate calibration shows significant potential for the prediction of freshness in squid. © 2021 Society of Chemical Industry.

Biogeochemical cycles of nutrients, rare earth elements (REEs) and Al in soil-plant system in ion-adsorption REE mine tailings remediated with amendment and ramie (Boehmeria nivea L.).

The exploitation of ion-adsorption rare earth element (REE) deposits in South China has left large areas of mine tailings. However, limited remediation practices on these tailings have been reported, and how the remediation strategies and economic plants cultivation affect the biogeochemical cycles of nutrients, REEs and Al remains unclear. The aim of the present study was to investigate the effects of the combination of the addition of soil amendment and the root development and activity of a fiber plant ramie (Boehmeria nivea L.) on the availability and distribution of nutrients, as well as of REEs and other potentially toxic elements (e.g. Al) in the soil-plant system. The results showed that the application of organic amendment and ramie planting induced a significant increase in soil pH, total carbon (C), nitrogen (N), and other nutrient (e.g. P and Ca) concentrations, while led to a decrease of 80-90% and 60-90% in soil extractable REE and Al concentrations respectively. Matrices of correlation showed that soil pH, total C, N, and P concentrations were among the most important factors controlling the availability of soil REEs and Al, and root characteristics (e.g. fine root length). The total C, N, P and extractable nutrient concentrations, and electrical conductivity were higher in the rhizosphere soils of ramie than those in the bulk soils. Moreover, more than 60% of the quantity of REE and Al in the whole ramie plant was stored within the thick roots. These results showed that, in addition to amendment, the effects induced by the roots of ramie could further improve soil properties through C input, nutrient mobilization and toxic element stabilization. Our study concludes that ramie planting with organic amendment is a promising phytostabilization strategy for the remediation of REE mine tailings in South China.

Plant-Soil Feedbacks for the Restoration of Degraded Mine Lands: A Review.

Much effort has been made to remediate the degraded mine lands that bring severe impacts to the natural environments. However, it remains unclear what drives the recovery of biodiversity and ecosystem functions, making the restoration of these fragile ecosystems a big challenge. The interactions among plant species, soil communities, and abiotic conditions, i.e., plant-soil feedbacks (PSFs), significantly influence vegetation development, plant community structure, and ultimately regulate the recovery of ecosystem multi-functionality. Here, we present a conceptual framework concerning PSFs patterns and potential mechanisms in degraded mine lands. Different from healthy ecosystems, mine lands are generally featured with harsh physical and chemical properties, which may have different PSFs and should be considered during the restoration. Usually, pioneer plants colonized in the mine lands can adapt to the stressful environment by forming tolerant functional traits and gathering specific soil microbial communities. Understanding the mechanisms of PSFs would enhance our ability to predict and alter both the composition of above- and below-ground communities, and improve the recovery of ecosystem functions in degraded mine lands. Finally, we put forward some challenges of the current PSFs study and discuss avenues for further research in the ecological restoration of degraded mine lands.

Identification of changes in volatile compounds in dry-cured fish during storage using HS-GC-IMS.

Changes in the volatile components of dry-cured fish during storage at 4 ℃ and 25 ℃ were investigated by HS-GC-IMS fingerprinting combined with principal component analysis (PCA). Topographic plots were used to establish the fingerprints of flavor substances, and 32 signal peaks were identified that corresponded to 22 compounds, mainly aldehydes, ketones, alcohols and esters. During storage at 4 ℃, 3-methylbutanal, dimethyl ketone and hexanal were the main volatile components, while hexanal, 1-octen-3-ol and 3-methylbutanal were the main compounds of dry-cured fish stored at 25 ℃; butyl methyl ketone was only observed at 25 °C. In the early stage of storage, significant changes in octanal, 3-methylbutanal and ethyl acetate were found in dry-cured fish at both temperatures (P < 0.05) while heptanal, pentanal and butanal changed significantly in the late stage (P < 0.05). PCA clearly distinguished the samples in relation to their storage temperature and time. In addition, heat map clustering analysis further revealed the differences and similarities among different samples, and those results were in accordance with the PCA results.

A quantitative comparable study on multi-hierarchy conformation of acid and pepsin-solubilized collagens from the skin of grass carp (Ctenopharyngodon idella).

This work aimed to improve yield of collagen from the grass carp skin by employing different strategies (acid-acid method, pepsin-pepsin method and acid-pepsin method, denoted as A-A, P-P, A-P, respectively). And further to conduct quantitative characterization on structural properties, self-assembly kinetics and gelation properties of these collagens. Herein, a two-step collagen extraction method (pepsin-pepsin) was established with the high yield. Meanwhile, structural measurements of high-yield collagen (pepsin-soluble collagen, PSC) and acid-soluble collagen (ASC) indicated that both collagens maintained the typical triple helical conformation of collagen type I. Moreover, the fibrillogenesis tests of PSC and ASC at the various temperatures confirmed that self-assembly were the entropy-driven process. The gelation time of both ASC and PSC was determined by the dynamic time sweep at the different frequencies combined with Winter's criterion. The self-assembly kinetics results showed that fibrillogenesis rate for ASC solution was faster, and more liable to gelation relative to PSC. Mechanical measurements suggested that ASC showed the more resistance ability to deformation than PSC due to more complicated architecture, confirmed by higher fractal dimension. However, the equivalent typical assemblies of PSC to ASC at the various stages can still be expected via controlling incubation time or temperature under the guidance of Arrhenius equation. This study would provide some strategies for achieving maximum utilization of waste biomass and significant insights into the mechanisms underlying the quantitative differences in multiple hierarchy conformation (molecule, fibrillogenesis and hydrogel) of ASC and PSC, which may benefit for subsequent design, development and optimization of collagen-based hydrogels in biomedical industries.

Self-assembly of collagen-based biomaterials: preparation, characterizations and biomedical applications.

The desired mechanical and biological performances of collagen that have led to its broad application as a building block in the biomedical field attributed to its intrinsic hierarchical structure from the nanoscale to macroscale, are discussed herein. Modulating the self-assembly process using regulatory factors can lead to obtaining collagenous materials with tuneable functional performance, which can then determine distinctive cellular responses. Herein, we present an overview of the corresponding characterization techniques used to detect the changes in light transmittance, architecture and mechanics during collagen fibrillogenesis. By combining regulatory parameters with characterization methods, researchers can selectively fabricate collagenous biomaterials with various functional responses.

Insights into the rheological behaviors evolution of alginate dialdehyde crosslinked collagen solutions evaluated by numerical models.

The elaboration of the rheological behaviors of alginate dialdehyde (ADA) crosslinked collagen solutions, along with the quantitative analysis via numerical models contribute to the controllable design of ADA crosslinked solution system's fluid mechanics performance during manufacturing process for collagen biomaterials. In the present work, steady shear flow, dynamical viscoelasticity, creep-recovery, thixotropy tests were performed to characterize the rheological behaviors of the collagen solutions incorporating of ADA from the different aspects and fitted with corresponding numerical models. It was found that pseudoplastic properties of all samples enhanced with increasing amounts of ADA, which was confirmed by the parameters calculated from the Ostwald-de Waele model, Carreau and Cross model, for instance, the non-Newtonian index (n) decreased from 0.786 to 0.201 and a great increase by 280 times in value of viscosity index (K) was obtained from Ostwald-de Waele model. The forth-mode Leonov model was selected to fit all dynamic modulus-frequency curves due to its higher fitting precision (R2>0.99). It could be found that the values of correlation shear viscosity (ηk) increased and the values of relaxation time (θk) decreased with increasing ADA at the fixed k value, suggesting that the incorporation of ADA accelerated the transformation of the collagen solutions from liquid-like to gel-like state due to more formation of CN linkages between aldehyde groups and lysine residues. Also, the curves of creep and recovery phase of the native and crosslinked collagen solutions were simulated well using Burger model and a semi-empirical model, respectively. The ability to resist to deformation and elasticity strengthened for the samples with higher amounts of ADA, accompanied with the important fact that compliance value (J50) decreased from 56.317Pa-1 to 2.135Pa-1 and the recovery percentage (Rcreep) increased from 2.651% to 28.217%. Finally, it was found that the area of thixotropic loop increased from 8.942Pa/s to 17.823Pa/s with increasing introduction of ADA, suggesting that stronger thixotropic behavior was associated with higher amount of ADA. Furthermore, Herschel-Bulkley model was employed to describe the up and down curves of all samples and it was confirmed that all collagen solutions belonged to pseudoplastic fluid (the flow index<1) without apparent yield stress and shear-thinning behaviors were more obvious with increasing additions of ADA according to the increasing consistency coefficient K values. Overall, this work contributed a new insight into the interactions between collagen and ADA based on quantitative rheological methods reflecting the different rheological properties and the results obtained should be of great utility in the extensive application of ADA crosslinked collagen solutions into diverse collagen-based materials.