Quercetagetin loaded in soy protein isolate–κ-carrageenan complex: Fabrication mechanism and protective effect

In the present study, the potential of soy protein isolate (SPI)–κ-carrageenan (κ-CG) complex as a protective carrier for quercetagetin was investigated at different pH values (pH 2.3 and 6.5). The particle size of the ternary aggregates was slightly increased at pH 2.3, yet dramatically decreased at pH 6.5 with increasing quercetagetin concentration. Moreover, the negative ζ-potential of the ternary aggregates was increased significantly (p < 0.05) at pH 6.5. The addition of quercetagetin to the SPI–κ-CG complex could highly quench the intrinsic fluorescence of SPI. Circular dichroism spectra further suggested that the bound quercetagetin could induce the rise of β-sheet and β-turn contents at the cost of α-helix and unordered coil fractions of SPI. In addition, quercetagetin could increase the viscoelasticity of the ternary aggregates at both pH. Furthermore, the SPI–κ-CG complex was found to be superior to single SPI or κ-CG in terms of improving light stability and radical scavenging ability of quercetagetin.     

A reliable and sensitive time-resolved fluorescent immunochromatographic assay (TRFICA) for ochratoxin A in agro-products

Immunochromatographic assays (ICAs) are considered as a suitable diagnostic tool for the detection of mycotoxins. Mycotoxins and especially, ochratoxin A are analytes with more demanding sensitivity requirements. To enhance the sensitivity of current immunochromatographic assays for ochratoxin A (OTA), a novel sensitive ICA was developed in this study. In the assay, microspheres enclosing fluorescent europium (III) [Eu(III)] nanoparticles (EuNPs) were used as a label for OTA monoclonal antibody (OTA-mAb) conjugation. Accordingly, assay was called time-resolved fluorescent immunochromatographic assay (TRFICA). The test strip was composed of three parts: a sample pad, nitrocellulose membrane and an absorbent pad. As for detection, a proper concentration of conjugated microspheres was pipetted into the microtube and sample extract was added to it. Then the strip was inserted into the tube and the fluid flow along the strip. The TRFICA results were obtained in 8 min and read by a portable TRFICA strip reader. The established method allows quantitative determination of OTA with limit of detection as low as 1.0 μg kg⁻¹ in the samples. For validation, spiked samples including wheat, maize, soybean and rice were respectively assayed by TRFICA and a standard high performance liquid chromatography equipped with a fluorescence detector (HPLC-FLD), and good agreement of results was obtained between two methods.     

国际化妆品监管模式对比分析与启示

研究美国、欧盟、日本和中国化妆品监管模式的异同,借鉴国外化妆品监管模式的先进经验,为促进中国化妆品监管创新,寻找更多的新方法、新工具、新标准、新制度,推进化妆品治理体系和治理能力的现代化提供参考。采用文献研究法和对比分析法,通过相关文献和网站等查找化妆品监管模式相关文件,对美国、欧盟、日本和中国四个国家地区化妆品的定义、监管部门、法律法规、相关社会组织及监管方法等方面进行对比分析。美国和欧盟监管体系较为成熟完备,监管模式又有各自不同的特点,日本和中国都向美欧接轨。欧盟采用市场主导模式,实施化妆品责任人制度和备案制度,相对弱化目前生产准入的事前监管,强化事中事后的政府监管,行业协会制定标准和规范行业自律等作用都处于世界领先水平。     

Isolation and characterization of Listeria monocytogenes in Chinese food obtained from the central area of China

The objective of this study was to investigate the prevalence and characteristics of Listeria monocytogenes isolated from Chinese food, including frozen dumplings, flavored raw meat, roasted meat, braised meat, and a cold vegetable dish with sauce. A total of 900 food samples were collected from supermarkets, open-air markets, and delicatessens in three large cities in the central area of China to examine the presence of L. monocytogenes; 21 (2.3%) of the samples were positive for this pathogen. Among the different samples, braised meat showed the highest L. monocytogenes detection rate (4.4%). Samples obtained from delicatessens showed a much higher L. monocytogenes contamination rate (8.3%) than those from open-air markets (6.7%) or supermarkets (0%). Multilocus sequence typing (MLST) analysis indicated that the 21 bacterial isolates belonged to 12 ST subgroups. ST5 was the largest and contained 7 isolates (33.3%); it was followed by ST474, ST121 and ST9 (each containing 2 isolates [10.5%]). Antibiotic susceptibility analysis showed that the 21 L. monocytogenes isolates were thoroughly resistant to cefoxitin but highly susceptible to doxycycline and ciprofloxacin. The presence of 10 virulence genes was evaluated by PCR, which showed that inlA, inlC, inlJ, prfA, hlyA, and plcB were present in all isolates and that inlB, actA, plcA and iap were present in 71.4–90.5% of the isolates. This study provides a useful reference for risk assessment and control of L. monocytogenes contamination in Chinese food and for the treatment of clinical listeriosis.     

Knowledge,attitudes and self-reported practices of food service staff regarding food hygiene in Edirne,Turkey

The purpose of this study was to evaluate the knowledge, attitudes and practices among food service staff with regards to food hygiene in hospitals in Edirne, Turkey, and to provide baseline data for implementing HACCP in hospital food services by carrying out a questionnaire by a face-to-face interview. The current study shows that food service staff in Edirne hospitals have insufficient knowledge regarding the basics of food hygiene. And also revealed a discrepancy between attitudes and practices towards food hygiene. There is an immediate need for continuous training among food handlers regarding safe food handling practices.     

Determination of 15 β-lactam antibiotics in pork muscle by matrix solid-phase dispersion extraction (MSPD) and ultra-high pressure liquid chromatography tandem mass spectrometry

An UPLC–MS/MS method based on matrix solid-phase dispersion (MSPD) was developed for simultaneous determination of 15 β-lactams in pork muscle. Muscle tissue was blended with Oasis HLB adsorbent. A column made from the sorbent/muscle tissue matrix was washed with hexane, after which β-lactams was eluted with acetonitrile/water (50:50, v/v) both containing 0.1% formic acid. The final extract was evaporated, and reconstituted into acetonitrile/water (10:90, v/v) for the analysis of UPLC-MS/MS. The correlation coefficient (r²) with each matrix-matched calibration curve is higher than 0.99. Limits of detection (LODs) and limits of quantification (LOQs) of β-lactams were ranged from 0.02 to 0.63 μg kg⁻¹ and 0.07–0.97 μg kg⁻¹, respectively. At the fortified levels, mean recoveries of all compounds were ranged from 92 to 111%, and the RSDs were lower than 12%. The method was accurate and reproducible, being successfully applied to the monitoring of 15 β-lactams in pork muscles obtained from the Chinese market.     

Stable auto-tuning of hybrid adaptive fuzzy/neural controllers for nonlinear systems

In direct adaptive control, the adaptation mechanism attempts to adjust a parameterized nonlinear controller to approximate an ideal controller. In the indirect case, however, we approximate parts of the plant dynamics that are used by a feedback controller to cancel the system nonlinearities. In both cases, “approximators” such as linear mappings, polynomials, fuzzy systems, or neural networks can be used as either the parameterized nonlinear controller or identifier model. In this paper, we present an algorithm to tune the adaptation gain for a gradient-based hybrid update law used for a class of nonlinear continuous-time systems in both direct and indirect cases. In our proposed algorithm, the adaptation gain is obtained by minimizing the instantaneous control energy. Finally, we will demonstrate the performance of the algorithm via a wing rock regulation example.     

The international risk governance council framework and its application to Listeria monocytogenes in soft cheese made from unpasteurised milk

The International Risk Governance Council (IRGC) developed a Risk Governance Framework whose purpose is to help policy makers, regulators and risk managers both understand the concept of risk governance and apply it to their handling of risks. The Framework allows input from the scientific and public health perspective as well as the less-easily measurable side of freedom of choice. For food, the public wants many choices and less regulation, but at the same time safe products to consume. These ideals are at times in conflict. One example of this is the demand for soft cheese made from unpasteurised milk which may be contaminated with L. monocytogenes or other pathogens. Distinguishing between simple, complex, uncertain and ambiguous risks can help to design a risk management strategy. Public health advocates typically see management of soft cheese made from unpasteurised milk as a simple risk (protection of health), whereas for a small but vociferous proportion of the public sees it more of an uncertain or ambiguous one (choice trumps the slight risk of illness). The implications of five management options for the cheese are discussed. The new Codex Guidelines tend to put these cheeses into Option 1, a strict control on the presence of the pathogen, which will be ignored by the cheese aficionados. Other options are worth exploring to give some more choice but at low risk.