Yukun Song

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 (R2 = 0.935) was established. Furthermore, good correlations (R2 > 0.950) between hardness, chewiness, rehydration ratio, and T22 relaxation of dried abalone were observed during the rehydration process.

Use of low-field-NMR and MRI to characterize water mobility and distribution in pacific oyster (Crassostrea gigas) during drying process

ABSTRACT Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) were used to monitor the water mobility and distribution of Pacific oyster during drying process. The results show the mobilities of bulk, immobilized, and free water were reduced, and the immobilized water was removed dramatically. T2-weighted images displayed the water decrease from the external surface to inner center of oyster during drying. In addition, excellent correlations between the total moisture content and T22 and A22 were observed with coefficients 0.9777 and 0.9832, respectively. Principal component analysis showed the drying degree of oyster could be monitored based on raw relaxation data. Thus, the result revealed that LF-NMR and MRI have great potential in assessing water mobility and distribution in oyster during drying process.

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.

Non-destructive measurement of water and fat contents, water dynamics during drying and adulteration detection of intact small yellow croaker by low field NMR

Non-destructive and fast measurement and characterization of fish is highly desired during various processing treatment. In this study, water dynamics during drying process and adulteration with carrageen were detected using low field nuclear magnetic resonance (LF-NMR) technique in small yellow croaker. Prediction models of water and fat contents were established based on LF-NMR Carr–Purcell–Meiboom–Gill (CPMG) data combined with principal component regression (PCR) or partial least squares regression (PLSR). The Rcv2 of water and fat content by PLSR model was 0.9877 and 0.9054, and the root mean square error (RMSE) of cross-validation was 9.2360 and 3.3730%, respectively. Water dynamics during hot-air drying process showed that the amount of immobile water significantly decreased, and good correlation was found between the moisture ratio and peak area by Two-term model. In addition, the adulterated small yellow croaker with carrageen or distilled water could be clearly distinguished by principal component analysis (PCA) in a fast and non-destructive manner. All the results demonstrated that the LF-NMR may have great potential in fast and non-destructive analysis of small yellow croakers during various processing treatment.

Effects of long‐term intake of Antarctic krill oils on artery blood pressure in spontaneously hypertensive rats

BACKGROUND In recent years, there has been a noticeable increase in research on krill oil (KO) for its health benefits. However, the action of KO in lowering blood pressure (BP) has not been studied yet. Therefore the aim of this study was to assess the ability of long-term KO supplementation to lower systolic BP (SBP) in spontaneously hypertensive rats (SHRs) and Sprague Dawley (SD) rats. RESULTS Compared with the blank control (BC) SHRs administered edible soybean oil, the high-dose (500 mg kg-1 body weight (BW)) KO-supplemented SHRs in the 2nd, 3rd, 4th and 5th weeks following oral administration, the mid-dose (100 mg kg-1 BW) KO-supplemented SHRs in the 4th and 5th weeks following oral administration and the low-dose (20 mg kg-1 BW) KO-supplemented SHRs in the 5th week following oral administration showed significantly lower SBP (P < 0.05). However, supplementation of KO had no significant effect on the SBP of healthy SD rats. Meanwhile, 5 weeks of KO administration significantly increased the serum levels of nitric oxide (NO) and total NO synthase of SHRs (P < 0.05). CONCLUSION KO has an antihypertensive effect in SHRs that is associated with an NO-related mechanism.

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.

Approach for monitoring the dynamic states of water in shrimp during drying process with LF-NMR and MRI

ABSTRACT The dynamic states of water in shrimp during drying process were investigated by low-field nuclear magnetic resonance and magnetic resonance imaging. With the extension of drying time, the transverse relaxation time of immobilized and free water significantly decreased, illustrating their mobility reduced. The signal per mass of immobilized water also decreased significantly, indicating its remarkable loss during drying process. Magnetic resonance imaging results revealed that the water signal intensity decreased from the external surface to inner regions of shrimp. Good correlations between the moisture content, hardness, chewiness, cohesiveness, L*, a* and nuclear magnetic resonance T2 parameters were observed by linear regression analysis.

Non-destructive analysis of caviar compositions using low-field nuclear magnetic resonance technique

Caviar is one of the most popular and expensive animal products in world trade. Water, fat and protein contents are key chemical compositions, and account for the majority of mass of caviar. In this study, the performance of a rapid, accurate analysis of water, fat and protein analysis was reported in caviar and raw sturgeon eggs through low-field 1H nuclear magnetic resonance (LF-NMR) relaxometry combined with partial least-squares regression (PLSR) models. For caviar, the correlation coefficients (Rcv2) of water, fat and protein were 0.9930, 0.9698 and 0.9783 with root mean square error of cross-validation (RMSECV) of 0.0760, 0.0308 and 0.0566, respectively. For raw sturgeon eggs the Rcv2 were 0.9932, 0.9592 and 0.9770, and the RMSECV were 0.1098, 0.0878 and 0.0917, respectively. Besides, a LF-NMR and principal component analysis (PCA) combined method also was developed to discriminate the caviar and raw sturgeon eggs based on the hydrogen protons originating from different environments with various salt concentrations.

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.