3种流通模式下生猪肉中单增李斯特菌的暴露评估

本研究通过对3 种生猪肉流通模式进行简化,根据生猪肉中单增李斯特菌初始污染水平抽检数据及调研环境参数,评估对比了3 种流通模式下单增李斯特菌在生猪肉中的最终暴露量。结果显示：基于全程非冷链的热鲜猪肉最终阳性检出率约为42.12%,超过风险阈值概率约为21.05%;基于部分冷链的冷鲜猪肉最终阳性检出率约为12.07%,超过风险阈值概率约为1.61%;基于全程冷链的冷鲜猪肉最终阳性检出率约为6.50%,超过风险阈值概率约为0%。相关性分析表明,初始污染水平与最终暴露量Pearson相关系数均为0.70以上,影响最大。因此,冷鲜猪肉较热鲜猪肉更有利于避免食源性疾病的发生,基于全程冷链的冷鲜猪肉应被积极推广。同时在生猪肉供应链中,更应注重源头控制,严格设置并控制各流通环节的环境条件。     

食源性致病菌菌株多相异质性对微生物风险评估的影响研究进展

微生物风险评估是当前保障食品安全的重要科学工具之一,被广泛应用于食品安全政策、法规和标准的制定。菌株多相异质性是微生物的固有特性,普遍存在于各类致病菌之中,影响着风险评估的准确性和不确定性。本文概述了国内外食品微生物菌株多相异质性的相关研究,总结了菌株多相异质性的概念,从生长和失活异质性、被膜形成异质性、毒力异质性和耐药异质性4 个方面全面系统地分析了菌株多相异质性的存在形式。在此基础上探讨了菌株多相异质性对微生物风险评估的影响,进一步展望了降低该影响的4 种解决措施,提出微生物风险评估宏模型的概念,以期提高食品安全风险评估的准确性和可靠性。     

2017年山西省食源性疾病流行病学特征及空间聚集性分析

目的 分析2017年山西省食源性疾病流行病学特征,重点探索其空间聚集情况,为科学地开展防控措施提供依据。方法 运用地理信息系统技术和描述性流行病学方法分析2017年山西省食源性疾病流行病学特征,并运用空间自相关方法研究其空间聚集性。结果 2017年山西省共报告食源性疾病病例27 727例,报告发病率为7.5/万。男女性别比为1.02∶1,20～39岁报告病例数最多(27.6%,7 661/27 727);农民(40.6%,11 266/27 727)、低龄学生(13.2%,3 652/27 727)报告病例数较多。可疑暴露食品主要为水果类及其制品(26.0%,7 207/27 719)、粮食类及其制品(17.9%,4 963/27 719)和肉与肉制品(11.6%,3 207/27 719)。进食场所以家庭为主(73.2%,23 429/31 988)。三维趋势分析得到的疾病报告发病率总体分布情况为:由北向南逐渐升高,由西向东缓慢下降,与报告发病率分布图所呈现的结果一致。食源性疾病报告发病率呈空间正相关,高-高聚集地区为浮山县、隰县、大宁县、永和县、古县、吉县。结论 山西省食源性疾病发病存在明显的空间聚集性。     

Dual effectiveness of sodium chlorite for enzymatic browning inhibition and microbial inactivation on fresh-cut apples

The dual effectiveness of sodium chlorite for browning inhibition and microbial inactivation on fresh-cut apples was investigated and compared to other anti-browning and antimicrobial agents. Results indicate that sodium chlorite significantly (P < 0.001) inhibited the browning reaction of fresh-cut Red Delicious apples stored at 5 °C for 14 days. This treatment also significantly reduced polyphenol oxidase activities. Treatments with acidified sodium chlorite, calcium chloride, or calcium ascorbate exhibited strong inhibition on apple browning during the early storage, these treatment effects diminished after 7 days in storage. Combining calcium chloride with sodium chlorite further significantly (P < 0.001) improved the firmness of apple slices, and browning inhibition during storage. Additionally, treatments with acidified sodium chlorite, sodium chlorite, or the combination of sodium chlorite and calcium chloride significantly (P < 0.001) reduced Escherichia coli populations on fresh-cut apples by 3.0, 3.6, and 3.9 log cfu g⁻¹ over the water control. The dual effectiveness of sodium chlorite to inhibit enzymatic browning and inactivate E. coli may allow this compound to achieve a prominent role in improving the quality and safety of products in the fresh-cut apple and other food industries.     

Effectiveness of Secondary Digesters as a Pathogen Controller in Winter

A revision of the Regulations regarding the use of sewage sludge in agriculture has forced a change in emphasis in sludge treatment from stabilisation to achieving pathogen kill. Previous work carried out by United Utilities Service Delivery highlighted temperature as being a key factor in pathogen kill in mesophilic anaerobic digestion and a possible important factor in pathogen destruction in secondary digestion, which is normally carried out in large open tanks where temperature control is not possible. It was found that temperature is a key factor in the rate of pathogen de-activation under isothermal conditions. However, in the full-scale secondary digester trial under winter conditions it was found that there was a significant difference between the surface temperature and the bulk temperature within the sludge; at the surface the temperature decreased more quickly. There was no significant difference between the performance of the 'old'and 'new'design of concrete tank with respect to wall thickness, cooling rates and E. coli reduction rate. The glass-coated steel-tank design showed a marked increase in the cooling rate and, despite the low ambient temperatures and fluctuating sludge temperature, a minimum 1-log reduction in E. coli was achieved.     

Establishment of a method for the simultaneous detection of four foodborne pathogens using high-throughput suspension array xTAG technology

The purpose of this study is to establish a rapid and accurate method based on multiplex polymerase chain reaction (PCR) combined with suspension array xTAG (Flexible Sequence-tagged, xTAG) technology to simultaneously detect Salmonella Typhimurium, Brucella spp., Bacillus cereus and Shigella spp. in raw milk. The primers were designed based on the specific target gene of the four pathogenic bacteria, and then the TAG sequence was used to modify the primers. First, the products of PCR were hybridised with microspheres labelled with anti-TAG, and then they were conjugated to streptavidin phycoerythrin. Finally, the products were detected on a Luminex 200 analyser. The results showed that the detection of milk samples demonstrated 100% specificity. The hybridisation conditions were successfully optimised. We successfully constructed a rapid, simple and high-throughput method to detect four foodborne pathogens. In conclusion, the established xTAG detection method provides a highly specific and reliable way to detect four kinds of foodborne pathogens in milk products.     

Cooking with elaborate recipes can reduce the formation of mutagenic heterocyclic amines and promote co-mutagenic amines

Heterocyclic amines (HCAs) are foodborne carcinogens for which their formation is highly dependent on cooking conditions. HCAs have been commonly quantified in food items prepared with simple procedures. This approach is suitable for elucidating HCAs’ formation, but it only partially reflects the contamination in consumed food. In the current investigation, the generation of HCAs has been investigated in fried beef items prepared with elaborated cooking recipes, and their occurrence has been compared with control beef fried without the addition of ingredients other than oil. The food recipes that included a variety of food ingredients had lower yields of mutagenic HCAs (≥47% reduction, with individual HCA levels ranging between 0.01 and 2.22 ng/g) with respect to the control beef. In contrast, the co-mutagens norharman and harman were formed generally at greater levels (up to three times the contamination in the control fried beef) in the items prepared including a greater variety of ingredients.     

Review: Comparison of the effectiveness of decontaminating strategies for fresh fruits and vegetables and related limitations

ABSTRACT

Given that it should be aware of the nutritional benefits, resulting from the consumption of fresh fruits and vegetables consumed raw and/or minimally processed, comparing the efficacy of different individual sanitizing methods against the major food-borne pathogens localized in fresh commodities is of much importance; these products are easily vulnerable to the microbial contamination. In this review, the current propensity of alternative sanitizing methods was introduced, as well as principal elements for deteriorating the cleaning effects were also discussed. Chlorine-based-sanitizers exhibited the microbial reduction of <1.12 log₁₀ CFU/g on fruits and vegetables. Most of aqueous disinfectants showed ≤3.01 log₁₀-redcutions against a variety of microorganisms inoculated on fresh commodities. Similarly, several physical technologies such as hydrostatic pressure and ultraviolet light were effective for reducing surviving bacterial cells could recover and grow rapidly during the whole processing, posing a potential risk of causing food-borne outbreaks associated with the fresh products. The invasion and subsequent localization of the organisms into the inner parts of products, interactions between the microbial cell and food-contacting surfaces, as well as development of biofilms could restrict the antimicrobial activity of the currently used approaches.     

Silage review: Foodborne pathogens in silage and their mitigation by silage additives

Silage is one of the main ingredients in dairy cattle diets and it is an important source of nutrients, particularly energy and digestible fiber. Unlike properly made and managed silage, poorly made or contaminated silage can also be a source of pathogenic bacteria that may decrease dairy cow performance, reduce the safety and quality dairy products, and compromise animal and human health. Some of the pathogenic bacteria that are frequently or occasionally associated with silage are enterobacteria, Listeria, Bacillus spp., Clostridium spp., and Salmonella. The symptoms caused by these bacteria in dairy cows vary from mild diarrhea and reduced feed intake by Clostridium spp. to death and abortion by Listeria. Contamination of food products with pathogenic bacteria can cause losses of millions of dollars due to recalls of unsafe foods and decreases in the shelf life of dairy products. The presence of pathogenic bacteria in silage is usually due to contamination or poor management during the fermentation, aerobic exposure, or feed-out stages. Silage additives and inoculants can improve the safety of silage as well as the fermentation, nutrient recovery, quality, and shelf life. This review summarizes the literature on the main foodborne pathogens that occasionally infest silage and how additives can improve silage safety.