Guangdong Testing Institute of Product Quality Supervision

Daliang, China

Guangdong Testing Institute of Product Quality Supervision

Daliang, China
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Liu H.,University of South China | Liu H.,Guangdong Testing Institute of Product Quality Supervision | Wang Z.,Shenzhen Center for Chronic Disease Control | Zhang Y.,Guangdong Testing Institute of Product Quality Supervision | And 4 more authors.
Journal of Chinese Institute of Food Science and Technology | Year: 2017

The aim of the present study was to investigate the distribution of phthalic acid esters pollution in total diet of Shenzhen population. Dietary exposure was achieved based on made food samples from Shenzhen total diet study. Gas chromatography-mass spectroscopy (GC-MS) methods were established to determine 16 phthalic acid esters from mixed samples and single sample after sample pre-treatment, then the contents of phthalate pollution in samples were estimated. The results showed that the highest levels of DMP, DBP, DIBP, DEP and DEHP from the mixed diet samples in urban area were 0.0672, 0.3304, 0.3590, 0.4537, 0.4588 mg/kg respectively; and that of DMP, DBP, DIBP, DEP and DEHP in suburban area were 0.4347, 1.8357, 0.5051, 0.0909, 6.1565 mg/kg respectively. The contamination levels of DEP and DEHP were more serious compared with DMP, DIBP and DBP in urban area while the contamination levels of DBP and DEHP were higher than DEP, DMP and DIBP in urban area. In the whole, pollution levels of 4 kinds of mixed samples such as potatoes, meats, eggs, aquatic and products were higher than others. For the single sample, the eel had the highest DEP concentration among the detected foods (14.5378 mg/kg). Also potato chip had the highest DMP level (0.8525 mg/kg), the crucian carp had the highest DEHP level (13.3437 mg/kg) and the quail eggs had highest DIBP and DBP levels (0.8562 mg/kg and 2.3118 mg/kg). Compared with other reported data from homeland and abroad, overall dietary contamination of phthalic acid esters for Shenzhen was kept at a low level. © 2017, Editorial Office of Journal of CIFST. All right reserved.

Jiang D.-W.,South China Agricultural University | Huang J.-J.,Guangdong Testing Institute of Product Quality Supervision | Yang G.-M.,South China Agricultural University | Du B.,South China Agricultural University
Modern Food Science and Technology | Year: 2013

To obtain the optimum ultra high pressure-assisted extraction technology of tea-polyphenols from low value tea. On the basis of single-factor test, the mathematical regression model is established about the dependent variable(extraction yield of tea-polyphenols ) and independent variables (alcohol concentration, time of maintain pressure and extraction pressure) through Box-Benhnken center composite design and response surface methodology. The results indicated that the optimal extraction conditions were alcohol concentration of 60%, processing time of 1.5 min, extraction pressure of 300 MPa. Under these conditions, the predictive maximum yield of tea-polyphenols from low value tea was 31.07%, the validation value was 30.87%. The relative error between them was 2.59%. The standardized regression equation was Y1=776.3561-1.3356X1 + 123.093X2 + 163.7406X3 - 274.2023X1X1 - 145.2251X2X2.

Wu W.-L.,Guangdong Testing Institute of Product Quality Supervision | Wu W.-L.,South China University of Technology | Pan L.-Y.,South China University of Technology | Tan Z.-Q.,South China University of Technology | And 7 more authors.
European Journal of Lipid Science and Technology | Year: 2014

The first aim of the present work was to assess the caloric value of low-calorie cocoa butter (LCCB) prepared by enzymatic transesterification. A growth method on restricted diet was utilized for the assessment with cocoa butter (CB) as a caloric control. Thirty weanling Wistar male rats were divided into six groups and fed for 3 weeks. The estimated caloric value of LCCB was 4.70kcal/g, exhibited a decrement of 31%. Furthermore, a growth experiment using pair-feeding protocol was performed to evaluate whether high LCCB diet could have any effect on the biochemical and physiological parameters, such as TAG, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, enzymatic activities of superoxide dismutase and catalase, Lee's index, liver index, the atherosclerosis index, and the risk of coronary heart disease. The results revealed that high LCCB dietary intake did not significantly alter the biochemical parameters except for the LDL-c. The fatty acid compositions of plasmas and feces demonstrated that caprylic acid was completely consumed through hepatic portal vein for energy supply, while most behenic acid was excreted. These results suggest that the calorie of CB has been lowered by transesterification and the high LCCB diet do not readily induce obesity or oxidative stress. Practical applications: A method to evaluate the caloric value of fats and oils is presented. A low-calorie cocoa butter may be useful for the chocolate industry. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yi S.-G.,Sun Yat Sen University | Zhang W.-H.,Sun Yat Sen University | Zhang W.-H.,Guangdong Testing Institute of Product Quality Supervision | Ai B.,Sun Yat Sen University | And 2 more authors.
Chinese Physics B | Year: 2014

In this paper, based on the equivalent single diode circuit model of the solar cell, an equivalent circuit diagram for two serial solar cells is drawn. Its equations of current and voltage are derived from Kirchhoff's current and voltage law. First, parameters are obtained from the I - V (current - voltage) curves for typical monocrystalline silicon solar cells (125 mm × 125 mm). Then, by regarding photo-generated current, shunt resistance, serial resistance of the first solar cell, and resistance load as the variables. The properties of shunt currents (Ish1 and Ish2), diode currents (I D1 and ID2), and load current (IL) for the whole two serial solar cells are numerically analyzed in these four cases for the first time, and the corresponding physical explanations are made. We find that these parameters have different influences on the internal currents of solar cells. Our results will provide a reference for developing higher efficiency solar cell module and contribute to the better understanding of the reason of efficiency loss of solar cell module. © 2014 Chinese Physical Society and IOP Publishing Ltd.

Yi S.G.,Yulin Normal University | Yi S.G.,Sun Yat Sen University | Zhang W.H.,Sun Yat Sen University | Zhang W.H.,Guangdong Testing Institute of Product Quality Supervision | And 4 more authors.
Science China Technological Sciences | Year: 2016

In view of the universality of the parallel connection of solar cells and their mismatch problem, in the present paper, we select two shunt solar cells (connected in parallel) as our research object, and use the equivalent one-diode circuit of the solar cell and the analysis of the two-body model. At first, the equations of current and voltage are deduced from the related electrical laws and the circuit diagram of the two solar cells connected in parallel. Then, according to the experimentally measured data of typical single-crystalline silicon solar cells (125 mm×125 mm), we select the appropriate simulation parameters. Following this, by using the photo-generated current, the shunt resistance, and the serial resistance of one of the shunt solar cells and the load resistance as independent variables, in turn, the changing characteristics of each branch current in the two shunt solar cells are numerically discussed and analyzed for these four cases for the first time. At the same time, we provide a simple physical explanation for the modeling results. Our analyses show that these parameters have different impacts on the internal currents of solar cells connected in parallel. These results provide a reference to solve the problem of connecting solar cells and to develop higher efficiency solar cells and systems. Meanwhile, the results will contribute to a better comprehension of the reasons for efficiency loss of solar cells and systems, and deepen the understanding of the electrical of solar cells behavior for high performance photovoltaic applications. © 2016, Science China Press and Springer-Verlag Berlin Heidelberg.

Wu W.-L.,China National Institute for Nutrition and Food Safety | Wu W.-L.,Guangdong Testing Institute of Product Quality Supervision | Wu W.-L.,South China University of Technology | Zhou Q.,Review Centre | And 7 more authors.
Journal of Chemical and Engineering Data | Year: 2016

This study presents the adsorption behavior of strong-base anion exchange D202 resin for the elimination of free fatty acids (FFAs) from structure-lipid in nonpolar solvent. The kinetics and thermodynamic behaviors that govern FFAs removal by D202 resin were investigated, and appropriate equilibrium isotherm and kinetics models for the removal in batch experiments were identified. Both the Freundlich and Langmuir adsorption isotherm models were fitted to the experimental results with the best fit obtained by the latter. The adsorption capacity of D202 resin was 235.69 mg·g-1, as calculated from the nonlinear model of the Langmuir adsorption. The experimental data from the batch adsorption processes were analyzed in terms of the parameters from three adsorption kinetics models, namely, the liquid-film diffusion, the intraparticle, and the chemical-reaction models, to estimate the fit for the adsorption in these systems. The outcomes indicate that the adsorption kinetics between the free fatty acid ions and resin are controlled by liquid-film diffusion as the rate-determining step. In addition, the activation energy (Ea) and the changes in the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) obtained from the thermodynamic studies reveal that the ion exchange adsorption of FFAs on D202 resin is a spontaneous, endothermic, and entropy-driven process. © 2016 American Chemical Society.

Wu W.-L.,Guangdong Testing Institute of Product Quality Supervision | Wu W.-L.,South China University of Technology | Tan Z.-Q.,South China University of Technology | Wu G.-J.,Zhongkai University of Agriculture and Engineering | And 6 more authors.
Separation and Purification Technology | Year: 2013

A feasible and novel deacidification process for the production of refined low-calorie cocoa butter by liquid-liquid extraction and anion exchange resin was investigated. The results showed that ethanol was a better solvent for extraction than methanol and isopropanol. The commercially available anion exchange resin D202 used in the experiments had a maximum adsorption capacity of 223.71 mg/g. With a two-stage extraction using 85 vol.% aqueous ethanol and an interaction time with resin of 4 h under the optimum conditions, low-calorie cocoa butter with an acid value of 0.81 mg KOH/g was obtained. Stable and qualified final products were acquired from 10 batches, indicating that the integrated process had no significant tendency to change the characteristics of low-calorie cocoa butter. The D202 anion exchange resin was regenerated and reused in 38 consecutive batches. © 2012 Elsevier B.V. All rights reserved.

Chu Y.,South China Agricultural University | Liang D.,Guangdong Testing Institute of Product Quality Supervision | Sun Y.,South China Agricultural University | Sun Y.,Guangdong Provincial Key Laboratory of Food Quality and Safety | And 3 more authors.
Journal of the Chinese Cereals and Oils Association | Year: 2014

A gas chromatography-mass spectrometry method has been developed for the simultaneous determination on 16 phthalate acid esters (PAEs) in different kinds of foods. Different separation and purification methods have been selected according to the types of foods. The oily samples were extracted with normal hexane by ultrasonically assisted procedure; the extracts were cleaned up by GPC and determined by GC-MS. Within the range of phthalate acid esters concentration of 0.02~5 mg/L, a fine relationship was observed between the peak area and the phthalic esters concentration. All of the correlation coefficients were higher than 0.999.The detection limit was achieved as 0.02 mg/kg. The recovery range of 16 phthalate acid esters was 75%~115% with the relative standard deviation (RSD, n=3) of 1%~10%.

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