Search

This study was performed to develop and validate a predictive growth model of pathogenic Escherichia coli to ensure the safety of fresh‐cut produce. Samples were inoculated with a cocktail of seven E. coli strains of five pathotypes (EHEC, Enterohemorrhagic E. coli; ETEC, Enterotoxigenic E. coli; EPEC, Enteropathogenic E. coli; EIEC, Enteroinvasive E. coli, and EAEC, Enteroaggregative E. coli) and stored at 4, 10, 12, 15, 25, 30, and 37°C. Growth of pathogenic E. coli was observed above 12°C. The primary growth model for pathogenic E. coli in fresh‐cut produce was developed based on the Baranyi model. The secondary model was developed as a function of temperature for lag phase duration (LPD) and maximum specific growth rate (μmax) based on the polynomial second‐order model. The primary and secondary models for pathogenic E. coli were fitted with a high degree of goodness of fit (R2 ≥ 0.99). The bias factor (Bf), accuracy factor (Af), and root mean square error (RMSE) were 0.995, 1.011, and 0.084, respectively. The growth model we developed can provide useful data for assessing the quantitative microbial risk of pathogenic E. coli in fresh‐cut produce intended for human consumption. In addition, it is thought to be widely available in industries that produce, process, distribute, and sell fresh‐cut produce., Primary model of the growth of pathogenic Escherichia coli in fresh‐cut produce. (A) 4°C, (B) 10°C, (C) 12°C, (D) 15°C, (E) 25°C, (F) 30°C, (G) 37°C.

Background: The present study examined the changes in microbiological composition during the production process of crab marinated in soy sauce, potential microbial hazards, potential contamination routes and effective critical control points. Crab and soy sauce samples were obtained from six different manufacturing plants at different stages, and their microbiological content was comprehensively assessed by quantitative and qualitative analyses.; Results: The results revealed the following: (1) the final products contained 4.0 log colony-forming units (CFU) g-1 aerobic plate counts (APCs) and 1.1 log CFU g-1 coliforms, which may have been introduced from the raw materials (the level of APCs in raw crab and soy sauce mixed with other ingredients was 3.8 log CFU g-1 and 4.0 log CFU mL-1 respectively); (2) marination of crab in soy sauce may allow cross-contamination by coliforms; (3) only Bacillus cereus and Staphylococcus aureus were qualitatively detected in samples at different stages of manufacture (detection rate of 28 and 5.6% respectively), and these bacteria may impact the microbiological quality and safety of crab marinated in soy sauce; and (4) bacterial counts were either maintained or increased during the manufacturing process (suggesting that no particular step can be targeted to reduce bacterial counts).; Conclusion: Proper management of raw materials and the marination process are effective critical control points, and alternative interventions may be needed to control bacterial quantity. The results provide important basic information about the production of crab marinated in soy sauce and may facilitate effective implementation of sanitary management practices in related industries and research fields. © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

The Nocardia sp. L-417 strain grown with n-hexadecane as a carbon source produced two types of biosurfactant that have different characteristics. These biosurfactants were purified by procedures that included ammonium sulphate fractionation, chilled acetone and hexane treatments, silica-gel column chromatography and Sephadex LH-20 gel filtration. The purified biosurfactants were very stable over a broad range of pHs (2-12) and temperatures (100 degrees C, 3 h). The biosurfactant type I had strong properties as an emulsifying agent and as an emulsion-stabilizing agent, whereas type II had a strong ability to reduce surface tension.