He Qian

A novel surface-enhanced Raman scattering sensor to detect prohibited colorants in food by graphene/silver nanocomposite

A novel surface-enhanced Raman scattering (SERS) sensor made up of a graphene and silver nanocomposite was developed for detecting prohibited colorants in food. This SERS platform exhibited an excellent enrichment effect between the colorant molecules and the graphene and an ability to enhance the Raman spectra of the silver nanoparticles. Detection of different concentrations of each prohibited colorant was carried out by SERS measurements on this novel substrate. In addition, from the SERS spectra of a mixture of four kinds of prohibited colorants, it was possible to easily distinguish each colorant by its characteristic peaks. A control experiment was also performed to compare the SERS spectra obtained using the graphene/silver nanocomposite substrate with spectra obtained using Ag alone as a substrate. The results showed that the SERS nanocomposite was better for detecting prohibited colorants. The proposed method has advantages in terms of providing a simple and rapid method for the sensitive analysis of prohibited additive colorants in food.

Label-free detection of the foodborne pathogens of Enterobacteriaceae by surface-enhanced Raman spectroscopy

Label-free and rapid assessment of foodborne pathogenic contamination, which can have significant implications for food safety, is critically important. In this study, seven foodborne bacteria (Salmonella typhimurium ATCC 50013, Salmonella O7HZ10, Shigella boydii CMCC51514, Shigella sonnei CMCC51529, Shigella dysenteriae CMCC51252, Citrobacter freundii ATCC43864, and Enterobacter sakazakii 154) have been examined, which are classified as Enterobacteriaceae according to biological taxonomy. They often have high rates of outbreak. A rapid and sensitive measurement method has been developed based on surface-enhanced Raman spectroscopy (SERS) coupled with gold nanoparticles as SERS substrates. The respective SERS spectra of the pathogens and their reproducibility have been compared. The principal component analysis (PCA) multivariate statistical technique has been employed to analyze the data, and a dendrogram cluster was constructed by hierarchical cluster analysis (HCA). Our results have shown that a rapid, sensitive, label-free identification of the foodborne pathogenic bacteria could be obtained by using gold nanoparticles as effective and stable SERS substrates.

Comparative studies by IR, Raman, and surface-enhanced Raman spectroscopy of azodicarbonamide, biurea and semicarbazide hydrochloride

Azodicarbonamide is widely applied in the food industry as a new flour gluten fortifier in China, Canada, the United States, and some other countries, whose metabolites of biurea and semicarbazide hydrochloride are reaction products during baking. In this study, IR, Raman and surface-enhanced Raman scattering (SERS) spectra of azodicarbonamide, biurea, and semicarbazide hydrochloride have been studied, and vibrational bands have been assigned on the basis of density functional theory (DFT) calculations. The calculated Raman spectra were in good agreement with experimental Raman spectra. The SERS method coupled with active gold substrates has also been applied for detection of the three chemicals with pure water as solvent, with the limit of detection of this method being as low as 10 μg/mL (less than 45 μg/mL). These results showed that azodicarbonamide and its metabolites could be detected by the vibrational spectra technique, which might be applied as a powerful tool for the rapid detection on these species derived from agents added to flour.

Hepatoprotective potential of Aloe vera polysaccharides against chronic alcohol-induced hepatotoxicity in mice.

BACKGROUND Aloe vera polysaccharides are reported to exhibit multiple biological effects, including anti-oxidation, anti-inflammation and immune enhancement. However, their influence on alcoholic liver disease (ALD) remains unclear. This study was designed to determine the protective effect of extracted A. vera polysaccharides (AVGP) against ALD in a chronic alcohol-feeding mouse model and investigate the possible underlying mechanisms. RESULTS Supplementation of AVGP significantly attenuated the levels of serum aminotransferases, lipids and hepatic TG and ameliorated histopathological alterations in the model of ALD. Interestingly, AVGP markedly up-regulated hepatic expression of lipolytic genes (AMPK-α2 and PPAR-α) but had no effect on lipogenic gene expression. AVGP diminished alcohol-dependent oxidative stress partly through a decrease in MDA and increase in GSH and SOD. Alcohol-induced inflammation was also mitigated by AVGP treatment via significant reduction in LPS and TNF-α, down-regulation of TLR-4 and MyD88 and up-regulation of IκB-α. CONCLUSION This study clearly showed that AVGP exerts a potent protective effect against chronic alcohol-induced liver injury. Its hepatoprotective effect appears to be associated with its antioxidant capacity and its ability to accelerate lipolysis and inhibit inflammatory response. The results indicate that AVGP could be considered as a potent food supplement in the prevention of ALD.

Theoretical calculation (DFT), Raman and surface-enhanced Raman scattering (SERS) study of ponceau 4R

Ponceau 4R is used as a coloring agent in many different products, such as food, drinks, medicines, cosmetics and tobacco. However, ponceau 4R also shows carcinogenic, teratogenic and mutagenic behavior in high doses. In this work, standard Raman, theoretical Raman and surface-enhanced Raman scattering (SERS) spectra have been used to investigate ponceau 4R. More specifically, density functional theory (DFT) calculations have been used to calculate the optimized Raman spectrum of ponceau 4R at the B3LYP/6-31G(d) level. This has provided a better understanding of the optimized geometry and vibrational frequencies of this dye. In addition, the experimental spectrum of ponceau 4R has been compared with the theoretical spectrum; good agreement was obtained. Finally, it has shown that using SERS the detection limit of the ponceau 4R solution can be as low as 5 μg/mL. This has been achieved by SERS measurements of ponceau 4R on a substrate of gold nanoparticles. The SERS peaks at 1030, 1236, 1356 and 1502 cm(-1) were chosen as index for semi-quantitative analysis, showing that the SERS technique provided a useful ultrasensitive method for the detection of ponceau 4R.

SiO2@Au nanoshells-based SERS method for detection of sunset yellow and chrysoidine.

A novel surface-enhanced Raman scattering (SERS) substrate made up of SiO2@Au nanoshells has been developed for detecting sunset yellow and chrysoidine. It exhibits an excellent enrichment SERS effect on these two colorant molecules. In this work, density functional theory (DFT) calculations have been carried out to determine the molecular structure and theoretical Raman spectra. This provided a good description of the characteristic peaks of the molecules. In addition, the appropriate thicknesses of the shell and environment pH have been derived to obtain improved SERS signals. The lowest concentration is 1 ppm and 0.5 ppm for sunset yellow and chrysoidine, respectively. Under optimal detection condition, it has proved possible to distinguish each colorant by its characteristic peaks in the SERS spectra of a mixture of the two colorants.

The suppression of torulene and torularhodin treatment on the growth of PC-3 xenograft prostate tumors

Torulene and torularhodin are two of the principal carotenoids in Sporidiobolus pararoseus and have a similar structure to that of lycopene. The present study was to elucidate the anti-cancer activity of torulene and torularhodin in vivo with lycopene as a control. Nude mice were orally supplemented every day with a low or high dose [9 or 18 mg/kg body weight (BW)] of lycopene, torularhodin or torulene. Two weeks after the supplementation, mice were injected once with hormone-independent prostatic carcinoma PC-3 cells. When the tumor of the control group load exceeded 200 mm(3), mice were killed and the study was terminated. Compared with the controls, high-carotenoid supplementation lowered the mean number of tumors from 248.13 ± 28.74 to 50.83 ± 7.63, 70.34 ± 6.77, and 60.53 ± 6.78 mm(3) (P < 0.05, n = 8) by, respectively. Histological examination showed tumor degeneration, apoptosis and necrosis presented at the end of the experiment. Quantitative polymerase chain reaction and immunohistochemistry results showed Bcl-2 expression of the control group was higher than that of the carotenoid-treated group while the expression of Bax was lower than the carotenoid-treated group. High-carotenoid supplementation also increased the mRNA expressions of caspase-3, 8 and 9 in tumor tissues. These results show that both torulene and torularhodin supplementation inhibit the growth of prostate cancer in nude mice and suggest that such an action is associated the apoptosis of tumor cells.

Release of bisphenols from can coatings into canned beer in China market.

BACKGROUND The aim of this research was to understand the migration of bisphenols from can coatings into foods in the Chinese market. RESULTS The migration of bisphenols was studied in commercial cans from the Chinese market filled with four types of food simulant (FS), which were heated at 121 °C for 30 min and stored at 40 °C for 30 days. Only bisphenol A (BPA) and bisphenol A diglycidyl ether (BADGE) were found in the can coatings, and SimC (10% (v/v) ethanol/water) was the most suitable FS for their release. The levels of these bisphenols in 24 kinds of canned beer from Chinese markets were also investigated. The average concentrations of BPA and BADGE were 2.85 ± 0.79 and 0.38 ± 0.19 µg · L⁻¹ respectively, which were both lower than the EU limits, and their respective daily intakes were estimated at 0.015 and 0.0020 µg · kg⁻¹ body weight · day⁻¹. Besides, increasing storage temperature and time accelerated the release of bisphenols into FSs. CONCLUSION The present results provide some guidance to reduce the migration of bisphenols during the transport and storage of canned foods.

Inhibitory effects of cinnamon and clove essential oils on mold growth on baked foods

This study evaluated the minimum inhibition concentration (MIC) and minimum lethal concentration (MLC) of cinnamon and clove essential oils against mold growth on green bean cake and finger citron crisp cake, and also examined the effects of these two essential oils and their application methods on the shelf life of the baked products in normal and vacuum packages by accelerated storage test. The results showed that the MIC of cinnamon and clove essential oils against molds were 0.21-0.83 and 0.21-1.67μL/mL, respectively and the MLC were 0.42-0.83 and 0.83-1.67μL/mL, respectively. In normal package cinnamon and clove essential oils could prolong the shelf life of green bean cake 9-10 and 3-4days, respectively and could prolong the shelf life of finger citron crisp cake 5-6 and 2-3days, respectively. And in vacuum package they were 15-16, 8-9, 10-12 and 7-9days, respectively in turn.

Rheological properties of phosphorylated exopolysaccharide produced by Sporidiobolus pararoseus JD-2.

The exopolysaccharide (EPS) produced by Sporidiobolus pararoseus JD-2 contained about 2.0% phosphorus and its zeta potential was -30mV at pH 6.0. This indicated that it was an anionic polymer. In steady shear measurements, there was a Newtonian plateau in low shear rates, but power-law behavior exhibited at high shear rates. So Williamson model was used to study the flow character of the EPS solutions. This phenomenon was according to its high molecular weight and entanglement networks. Considering the EPS was an anionic polymer, the influence of added salts on apparent viscosity of EPS were studied. Different NaCl concentrations had little effect on the viscosity of the EPS, but high concentrations of CaCl2 increased the viscosity of EPS significantly. EPS solutions showed inapparent thixotropic properties in stress growth and thixotropic loop experiment. According to the flow curve results and oscillatory shear results obtained, the rheological properties of EPS solutions were closer to that of entanglement network system, like carboxy methyl cellulose rather than weak gel structure such as xanthan gum. The EPS had the function to enhance immunological functions. Understanding the rheological characteristics of EPS was essential to exploit the functionality of this EPS in different food or medicine systems.