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15 results on '"Gu, Kejia"'

5. Psychological Impact During the First Outbreak of COVID-19 on Frontline Health Care Workers in Shanghai

Author

Feng, Jingjing, primary, Xu, Jinfu, additional, Xu, Susu, additional, Cao, Huifang, additional, Zheng, Cuixia, additional, Sharma, Lokesh, additional, Dela Cruz, Charles S., additional, Zhang, Jing, additional, Chu, Dejie, additional, Yu, Li, additional, Tu, Chunlin, additional, Li, Fan, additional, Ren, Tao, additional, Zhang, Fengying, additional, Du, Chunlin, additional, Gu, Wenchao, additional, Liu, Hongwei, additional, Qian, Yechang, additional, Shen, Changxing, additional, Tang, Chunhong, additional, Bi, Yueping, additional, Xiao, Feng, additional, Gu, Kejia, additional, Zhang, Jie, additional, Ye, Zheng, additional, Zhao, Liang, additional, Zhai, Jiayi, additional, Hu, Xiaoying, additional, Qu, Jieming, additional, and Jie, Zhijun, additional

Published
2021
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6. HEAT RESISTANCE COMPARISON OF SALMONELLA AND ENTEROCOCCUS FAECIUM IN CORNMEAL

Author

Gu, Kejia

Subjects
extrusion, z-value, surrogate, D-value
Abstract

Adequate surrogate identification is critical for validating in-plant thermal process controls for Salmonella inactivation in different food matrices. This study compared the thermal inactivation parameters (D- and z-values) and evaluated the heat resistance of Enterococcus faecium (8459) as a surrogate for a 5-serovar Salmonella cocktail in cornmeal. The cornmeal was spray inoculated with the respective bacteria to achieve ~9 log CFU/g population and set to the desired moisture contents (16, 22, and 28% w.b.). The inoculated cornmeal was then heat-treated at pre-determined temperatures (60, 64, and 68°C) in sealed aluminum thermal-death-time disks in hot water baths for pre-determined time intervals. Injury-recovery media [brain heart infusion (BHI) agar overlaid with xylose lysine deoxycholate (XLD) agar for Salmonella or BHI agar overlaid m-enterococcus agar for E. faecium] were used for microbial enumeration to account for thermally injured bacterial cells. The D-values of Salmonella in cornmeal at 16, 22, and 28% moisture content were 37.5, 8.4, and 2.4 min at 60°C, 19.9, 3.5, and 1.1 min at 64°C, and 10.1, 1.4, and 0.5 min at 68°C, respectively. Whereas the D-values of E. faecium in cornmeal at 16, 22, and 28% moisture content were 140.4, 18.9, and 3.3 min at 60°C, 78.4, 7.1, and 1.6 min at 64°C, and 37.3, 2.8, and 0.8 min at 68°C, respectively. The z-values of E. faecium and Salmonella in cornmeal at 16, 22, and 28% moisture content were 13.9, 9.7, and 12.5°C, and 14.0, 10.4, and 11.7°C, respectively. These results indicated similar or higher thermal resistance (D-values) and equivalent thermal sensitivity (z-values) of E. faecium compared to Salmonella at different moisture contents and respective temperatures (P ≤ 0.05). Therefore, E. faecium could be used as a surrogate for Salmonella during thermal process validation of cornmeal processing.

Published
2021
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15. Multiresidue Method for Determination of 183 Pesticide Residues in Leeks by Rapid Multiplug Filtration Cleanup and Gas Chromatography-Tandem Mass Spectrometry.

Author

Zou N, Han Y, Li Y, Qin Y, Gu K, Zhang J, Pan C, and Li X

Subjects
Limit of Detection, Pesticide Residues isolation & purification, Solid Phase Extraction, Tandem Mass Spectrometry methods, Filtration methods, Food Contamination analysis, Gas Chromatography-Mass Spectrometry methods, Onions chemistry, Pesticide Residues chemistry
Abstract

This study reports the development of a novel multiplug filtration cleanup (m-PFC) procedure for analysis of pesticide residues in leek samples followed by gas chromatography-tandem mass spectrometry detection. The leek samples were initially purified following the dispersive solid-phase extraction with different sorbents to determine the most suitable proportioning of sorbent materials; then, the m-PFC method was carried out by applying the streamlined procedure with syringes. Average recoveries of most pesticides were in the range from 70.2 to 126.0% with the relative standard deviation < 20% with the m-PFC process. The limits of detection were 0.03-3.3 μg kg(-1). The limits of quantification were 0.1-10 μg kg(-1). The m-PFC process is convenient and time-efficient, taking just a few seconds per sample. Finally, the developed method was successfully applied to the determination of pesticide residues in market samples. In that analysis, 35 pesticides were detected in 29 samples, with values ranging from 2.0 to 9353.1 μg kg(-1).

Published
2016
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