Food safety and microbiological quality aspects of QDS process® and high pressure treatment of fermented fish sausages

A new fermented fish sausage product, based on monkfish, was developed by using an accelerated drying process, the QDS process^®. To evaluate food safety, a challenge test was performed, in which the raw materials were inoculated with low levels of Listeria monocytogenes and Salmonella enterica (≤150 CFU/g). The product was manufactured, fermented, QDS dried, and half of the samples were pressurized (600 MPa, 5 min, 13 °C). Pathogens, technological microbiota, spoilage indicator bacteria from fish (hydrogen sulphite producing bacteria, coliforms and Escherichia coli) and physicochemical parameters were monitored during manufacturing and after 6, 13, 20 and 27 days of refrigerated storage at 4 and 8 °C. Results showed that in the finished product, pathogens and spoilage indicator bacteria could not grow but decreased and E. coli was not detected during storage. Pressurization had an important reducing effect on technological microbiota, and eliminated L. monocytogenes, S. enterica, hydrogen sulphite producing bacteria and coliforms immediately after production and during refrigerated storage.     

Zinc oxide nanoparticles loaded active packaging,a challenge study against Salmonella typhimurium and Staphylococcus aureus in ready-to-eat poultry meat

Zinc oxide nanoparticles were prepared using hydrothermal synthesis approach. Formation of zinc oxide nanoparticles were confirmed by using UV–Vis spectrophotometer, Fourier transform infrared spectrometer and X-ray diffractometer. The particles size (≤100 nm) and structure of nanoparticles were studied under scanning and transmission electron microscope. The nanoparticles were used against two prominent foodborne pathogens, Salmonella typhimurium and Staphylococcus aureus and were found highly effective against both of them. The antibacterial activity of the nanoparticles was determined in solid and liquid media using nutrient agar and broth. Zinc oxide nanoparticles loaded active film of calcium alginate was prepared for active packaging against the same foodborne pathogens (S. typhimurium and S. aureus). Presence and distribution of nanoparticles in active film were confirmed with Fourier transform infrared spectrometer, X-ray diffractometer and scanning electron microscopy. Zinc oxide nanoparticles loaded active films showed antibacterial activity against the target bacteria in Petri dish. The film was also used as an active packaging (a challenge study) in ready-to-eat poultry meat against the same pathogens, and reduced the number of inoculated target bacteria from log seven to zero within 10 days of its incubation at 8 ± 1 °C.     

合肥市即食肉类食品中金黄色葡萄球菌污染情况及耐药和基因型分布

目的调查合肥市即食肉类食品中金黄色葡萄球菌的污染情况,并对分离株进行耐药性分析及多位点序列分型研究。方法 2017年10月—2018年10月自合肥市区范围内的超市和开放型菜市场共采集744份即食型肉类食品样品。根据GB 4789.10—2016《食品安全国家标准食品微生物学检验金黄色葡萄球菌检验》中的方法对样品进行金黄色葡萄球菌定性和定量分析,采用K-B纸片扩散法检测分离株的耐药性,采用多位点序列分型法对分离株进行ST分型,使用MEGA 7.0绘制聚类树状图。结果样品中金黄色葡萄球菌检出率为4.2%(31/744),其中卤肉制品检出率最高为8.1%(15/185),其次为烤肉制品(6.3%,11/174),定量分析显示超过90%的样品金黄色葡萄球菌污染水平在0.3～10 MPN/g范围内。耐药性分析结果显示80.6%(25/31)的菌株对青霉素G耐药,40%以上的菌株对链霉素、红霉素和卡那霉素耐药;多重耐药菌株占比为61.3%(19/31)。分型分析共获得8个ST型,分别为ST6、ST7、ST15、ST59、ST72、ST188、ST398和ST2196型,其中以ST188和ST72型为主。结论合肥市卤肉和烤肉制品中存在金黄色葡萄球菌污染,且多重耐药菌株比例较高,对消费者的健康有潜在威胁,有必要持续监测污染率、菌株耐药和基因型流行趋势,完善合肥市食源性金黄色葡萄球菌感染的风险评估。     

Free D-amino acids determination in ready-to-eat cooked ham irradiated with electron-beam by indirect chiral HPLC

Potential racemization of L-amino acids (AA) in ready-to-eat (RTE) cooked ham after hygienization by electron-beam irradiation between 1 and 8 kGy was studied. An indirect chiral method based on the derivatization reaction of AA with o-phthaldialdehyde and N-acetyl-L-cysteine followed by reversed-phase HPLC and fluorimetric detection was applied to detect ten enantiomeric pairs of free AA (Asp, Ser, Thr, Ala, Tyr, Val, Trp, Phe and Leu). Five of the D-AA were not found in any of the samples analyzed; the other five remaining D-AA (D-Asp, D-Ser, D-Ala, D-Val and D-Leu) were detected both in irradiated and non-irradiated cooked ham samples, their content being in the range 1.25–13.79 μg/g. Although significant differences appeared for a few of the samples and doses, no positive correlation between the D-AA content and the irradiation doses was observed. Therefore, the electron-beam irradiation technique could be useful for sanitation of packed RTE cooked ham at doses allowed by WHO and EU, since it remains chemically safe to eat.     

罗非鱼鱼肉的解吸平衡规律研究

罗非鱼鱼肉的解吸平衡含水率不但决定给定干燥条件下所能达到的最低水分,且直接影响干燥速度,本文采用静态称重法研究了罗非鱼鱼肉在不同温度(40℃～60℃)和不同相对湿度(11.0～84.0%)条件下的解吸平衡含水率的变化规律,比较了罗非鱼背部和腹部肌肉在恒温60℃和不同湿度下的解吸平衡含水率的差异,分析了温、湿度对鱼肉的平衡含水率的影响,并对试验测定的结果进行了回归分析,得出Chung-Pfost模型最适宜描述罗非鱼鱼肉的平衡含水率变化。     

色泽异常肉的检验和处理

本文通过对市场上五种常见色泽异常肉的检验与处理,为广大消费者提供了便利的鉴别手段,使“吃上放心肉”提供了可靠的依据,并在此基础上技术上有了新的改进。通过临床实践经验,采用对比法以及实验室快速检验法对五种常见色泽异常肉进行不同程度的处理。通过检验和处理常见色泽异常肉,反映了我国市场存在的严重问题,有待于我们进一步加强动检法。     

Consumption patterns,bacteriological quality and risk factors for Salmonella contamination in meat-based meals consumed outside the home in Kigali,Rwanda

Meat-based meals are consumed as a source of animal proteins and constitute one of the leading vehicles for food borne infections in humans. The main objective of this study was to determine the consumption pattern and the bacteriological quality of meat-based meals consumed outside households in Kigali. A survey on meat consumption patterns was carried out in 400 households by using a questionnaire, whereas different meat-based meals were sampled from 150 snack bars and restaurants. Enumeration of hygiene indicator bacteria (total mesophilic bacteria and Escherichia coli) and the qualitative detection of Salmonella were carried out by using conventional culture methods. The results indicated that goat was the type of meat that was consumed the most outside the home in Kigali and the meat intake varied significantly (p ≤ 0.05) with the social category of the household. The average levels of total aerobic bacteria and E. coli in meat-based meals were found to be 4.7 and 1.4 log cfu/g, respectively, whereas Salmonella was detected in 11.7% of all meat-based meals. Eight factors mostly linked to the cooking treatments and hygienic handling practices for cooked meals were found to be significantly (p ≤ 0.05) associated with the risk of Salmonella occurrence in meat-based meals consumed outside the home in Kigali. The findings from this study strongly suggest the need for proper cooking and/or improvements in hygiene in the establishments selling ready-to-eat meat-based meals in Kigali, particularly those located in rural localities.     

Antimicrobial resistance profiles of Listeria monocytogenes isolated from ready-to-eat products in Poland in 2007–2011

The aim of the study was to characterize strains of Listeria monocytogenes isolated from ready to eat (RTE) products collected as part of official food control and monitoring in Poland. A total of 105 L. monocytogenes isolates from RTE products: 54- cakes and 51 – delicatessen products were examined. The presence L. monocytogenes in cakes and delicatessen products was 0.4% and 0.7% respectively suggesting the level of contamination of RTE products with L. monocytogenes is very low.     

Modified atmosphere packaging of fresh meats–sudden partial adaptation caused an increase in sustainability of dutch supply chains of fresh meats

In the past decade, a major transition evolved in the Dutch fresh meat industry with ramifications for the entire meat business. In 1995, more than 95% of all fresh meat products for consumers were either sold loose or packed in the traditional way, i.e. on a white styrofoam tray with stretch wrap. Almost a decade later, about half of the meat industry has adapted the modified atmosphere packaging (MAP) technology. Strikingly, the first trials with this technology had already been conducted in The Netherlands in 1964, but it took four decades for the technology to conquer the Dutch meat industry. This paper argued that the partial adaptation of MAP diminished the product losses in fresh meat sales and hence the environmental impact of meat production and consumption. Copyright © 2007 John Wiley & Sons, Ltd.