Jingran Bi

Real-time detection of water dynamics in abalone (Haliotis discus hannai Ino) during drying and rehydration processes assessed by LF-NMR and MRI

ABSTRACT To detect the water dynamics in abalone during drying is essential for the textural quality improvement, however, sufficiently rapid and nondestructive methods of abalone moisture monitoring are currently lacking. In this study, water changes in abalone during drying and rehydration processes were assessed using low field nuclear magnetic resonance and magnetic resonance imaging. A close correlation was observed between ATotal and the total moisture content, and a prediction model with high correlation (R2u2009=u20090.935) was established. Furthermore, good correlations (R2u2009>u20090.950) between hardness, chewiness, rehydration ratio, and T22 relaxation of dried abalone were observed during the rehydration process.

Changes in Body Wall of Sea Cucumber (Stichopus japonicus) during a two-Step Heating Process Assessed by Rheology, LF-NMR, and Texture Profile Analysis

Sea cucumber (Stichopus japonicus) is regarded as a highly priced delicacy in Japan and China owing to its unique elasticity and palatability. Heating is an essential step to process sea cucumber with desired texture. In the present study, sea cucumber body wall was pre-heated at 40xa0°C, followed by post-heating at 80xa0°C. Changes in body wall were assessed by rheology, LF-NMR, and texture profile analysis. The small strain rheological analysis indicated that there were significant structural changes of body wall at about 40xa0°C during pre-heating. Large strain texture profile analysis and the storage modulus showed a good correlation. LF-NMR analysis displayed only one water population in samples pre-heated at 40xa0°C for up to 120xa0min, and the population did not change significantly with the heating duration. This demonstrated that structural changes and moisture loss from the inter collagen fibrils were not significant. As for samples post-heated at 80xa0°C, three distinct peaks were found and the T2 relaxation time and area of the bulk water decreased significantly, revealing significant changes of internal structures and loss of water-holding capacity. T2 parameters had a good correlation to texture profile analysis parameters for samples after both pre-heating and post-heating.

Physicochemical properties and cytotoxicity of carbon dots in grilled fish

In recent years, the presence of food-borne nanoparticles during food processing has been a controversial issue. In this paper, we introduced a class of extremely low-cytotoxicity carbon dots (CDs) extracted from grilled pike eel which have been consumed for thousands of years. These CDs are water-soluble, quasi-spherical, and nanosized (approximately 2.75 nm). UV illumination can excite CDs to emit a strong sapphire luminescence with a quantum yield as high as 68.7%. X-ray diffraction (XRD) analysis showed that these nanoparticles are amorphous attributed to the disordered carbon atoms. X-ray photoelectron spectroscopy (XPS) measurements showed that the CDs contain a predominant C1s peak at 284.43 eV and an O1s peak at 531.35 eV accompanied by a pronounced N1s peak at 399.34 eV, with the atomic percentages of 66.58%, 17.5% and 15.91%, respectively. Moreover, the CDs also have excellent biocompatibility and could ease into the cytoplasmic region of MC3T3-E1 cells without any seriously imposed toxicity against cells.

Presence and Formation Mechanism of Foodborne Carbonaceous Nanostructures from Roasted Pike Eel (Muraenesox cinereus)

Foodborne nanostructures have gained more and more attention in recent years. In this paper, the presence and physicochemical properties of carbonaceous nanostructures (CNSs) from roasted pike eel ( Muraenesox cinereus) were reported. The monodispersed CNSs are strongly photoluminescent under the illustration of ultraviolet (UV) light, with a fluorescent quantum yield of 80.16%, and display excitation-dependent emission behavior. The formation of CNSs is believed to go through a process of morphology evolution, including polymerization, pyrolysis, nucleation, growth, emergence, and blossom. The optical properties of the CNSs were shown to be affected by the roasting temperature. Furthermore, cellular uptake of the CNSs was investigated, and it is shown that the CNSs were clearly absorbed into live cells and were mainly distributed within the cell cytoplasm and not in the cell nucleus. This work is among the very first reports on CNSs present in roasted fish, providing valuable insights into the formation mechanism of such nanostructures and showcasing the biodistribution of these food-originated CNSs in live cells.

Nanostructures Derived from Starch and Chitosan for Fluorescence Bio-Imaging

Fluorescent nanostructures (NSs) derived from polysaccharides have drawn great attention as novel fluorescent probes for potential bio-imaging applications. Herein, we reported a facile alkali-assisted hydrothermal method to fabricate polysaccharide NSs using starch and chitosan as raw materials. Transmission electron microscopy (TEM) demonstrated that the average particle sizes are 14 nm and 75 nm for starch and chitosan NSs, respectively. Fourier transform infrared (FT-IR) spectroscopy analysis showed that there are a large number of hydroxyl or amino groups on the surface of these polysaccharide-based NSs. Strong fluorescence with an excitation-dependent emission behaviour was observed under ultraviolet excitation. Interestingly, the photostability of the NSs was found to be superior to fluorescein and rhodamine B. The quantum yield of starch NSs could reach 11.12% under the excitation of 360 nm. The oxidative metal ions including Cu(II), Hg(II)and Fe(III) exhibited a quench effect on the fluorescence intensity of the prepared NSs. Both of the two kinds of the multicoloured NSs showed a maximum fluorescence intensity at pH 7, while the fluorescence intensity decreased dramatically when they were put in an either acidic or basic environment (at pH 3 or 11). The cytotoxicity study of starch NSs showed that low cell cytotoxicity and 80% viability was found after 24 h incubation, when their concentration was less than 10 mg/mL. The study also showed the possibility of using the multicoloured starch NSs for mouse melanoma cells and guppy fish imaging.

Facile one-step synthesis of highly luminescent N-doped carbon dots as an efficient fluorescent probe for chromium(VI) detection based on the inner filter effect

Chromium is highly toxic and considered as a severe contaminate. Therefore, low cost, highly sensitive sensors for the determination of Cr(VI) are highly required. In the present study, highly luminescent N-doped carbon dots (CG-CDs) obtained from citric acid and glycine with a quantum yield of 78% and label-free fluorescent assay system were designed for Cr(VI) detection based on the inner filter effect (IFE). The CG-CDs were prepared by a one-step hydrothermal method using citric acid and glycine as carbon precursors. The fluorescent sensors showed rapid response, high selectivity, and sensitivity to Cr(VI). A good linear relationship between the concentration of Cr(VI) ions and fluorescence intensity was obtained in the range from 5 to 200 μmol L−1 (R2 = 0.98), and the limit of detection was calculated to be 4.16 μmol L−1 for Cr(VI). Importantly, this method has been successfully applied to the detection of Cr(VI) ions in simulated aquaculture water, which may be helpful to reduce the risk of Cr(VI) intake from contaminated water.

Bio-inspired Edible Superhydrophobic Interface for Reducing Residual Liquid Food

Significant wastage of residual liquid food, such as milk, yogurt, and honey, in food containers has attracted great attention. In this work, a bio-inspired edible superhydrophobic interface was fabricated using U.S. Food and Drug Administration-approved and edible honeycomb wax, arabic gum, and gelatin by a simple and low-cost method. The bio-inspired edible superhydrophobic interface showed multiscale structures, which were similar to that of a lotus leaf surface. This bio-inspired edible superhydrophobic interface displayed high contact angles for a variety of liquid foods, and the residue of liquid foods could be effectively reduced using the bio-inspired interface. To improve the adhesive force of the superhydrophobic interface, a flexible edible elastic film was fabricated between the interface and substrate material. After repeated folding and flushing for a long time, the interface still maintained excellent superhydrophobic property. The bio-inspired edible superhydrophobic interface showed good biocompatibility, which may have potential applications as a functional packaging interface material.

A fluorescence turn-off-on chemosensor based on carbon nanocages for detection of ascorbic acid

A new type of carbon nanocages (CNCs) has been constructed through grilling of turbot (Scophthalmus maximus L.) by a facile method, and applied successfully as a fluorescent probe for rapid, selective as well as sensitive detection of ascorbic acid (AA). The one-step fabricated CNCs were thoroughly characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and UV-vis spectroscopy. The CNCs showed very selective and sensitive quenching in the presence of Fe3+. The quenching efficiency of the CNCs was significantly correlated with the concentration of Fe3+ in the range 20–110 μM. The linear regression equation is y = 0.00868x − 0.0981 (R2 = 0.993) with the detection limit of the CNCs for Fe3+ at 3.96 μM. Furthermore, the fluorescence of CNCs–Fe3+ displayed a turn-on behavior upon adding AA due to the reduction of Fe3+ to Fe2+. A good linear relationship between the AA concentration and fluorescence intensity was obtained in the range of 2 to 12 μM (R2 = 0.998) with a detection limit of 97.2 nM of AA. The selectivity of the CNCs–Fe3+ for the detection of AA was explored in the presence of other possible reducing agents. Only AA induced a significant fluorescence restoration of CNCs–Fe3+, the signal being approximately 5-fold greater than with other reducing agents (uric acid, dopamine, human serum albumin, D-glucose and hemoglobin). Notably, the developed probe was successfully applied for the quantitative detection of AA in vitamin tablets with recoveries from 99.77% to 104.76%.

Functional food packaging for reducing residual liquid food: Thermo-resistant edible super-hydrophobic coating from coffee and beeswax

Edible super-hydrophobic coatings have attracted great attentions as they can avoid the waste of liquid foods, such as honey and milk, adhered to the inside of containers. However, the poor thermal stabilities of edible super-hydrophobic coatings restrict their applications. In this work, a thermo-resistant edible super-hydrophobic coating has been fabricated using beeswax and coffee, which are approved by U.S. Food and Drug Administration. This coating surface has the similar micro/nanoscale structure to that of the leaf surface. A variety of liquid foods can freely roll on this coating surface in spherical. This special wetting property effectively reduces the residue of liquid foods, when they are poured out of the containers. With the introduction of coffee lignin, the thermal stability and adhesive force of the coating increases significantly. The apparent contact angle of this coating can remain to be above 150° after a long-time heating and flushing. This thermo-resistant edible super-hydrophobic coating can solve the problem that original edible super-hydrophobic coating is not resistant to high temperature, and has a broad application prospect in the field of functional food packaging.

Unfolding/Refolding Study on Collagen from Sea Cucumber Based on 2D Fourier Transform Infrared Spectroscopy

We aimed to explore the differences of thermal behaviors between insoluble collagen fibrils (ICFs) and pepsin-solubilized collagens (PSCs) from sea cucumber Stichopus japonicus. The unfolding/refolding sequences of secondary structures of ICFs and PSCs during the heating and cooling cycle (5 → 70 → 5 °C) were identified by Fourier transform infrared spectrometry combined with curve-fitting and 2D correlation techniques. ICFs showed a higher proportion of α-helical structures and higher thermostability than PSCs, and thus had more-stable triple helical structures. The sequences of changes affecting the secondary structures during heating were essentially the same between ICFs and PSCs. In all cases, α-helix structure was the most important conformation and it disappeared to form a β-sheet structure. In the cooling cycle, ICFs showed a partially refolding ability, and the proportion of β-sheet structure rose before the increasing proportion of α-helix structure. PSCs did not obviously refold during the cooling stage.