New food safety challenges of viral contamination from a global perspective: Conventional,emerging, and novel methods of viral control

Food- and waterborne viruses, such as human norovirus, hepatitis A virus, hepatitis E virus, rotaviruses, astroviruses, adenoviruses, and enteroviruses, are major contributors to all foodborne illnesses. Their small size, structure, and ability to clump and attach to inanimate surfaces make viruses challenging to reduce or eliminate, especially in the presence of inorganic or organic soils. Besides traditional wet and dry methods of disinfection using chemicals and heat, emerging physical nonthermal decontamination techniques (irradiation, ultraviolet, pulsed light, high hydrostatic pressure, cold atmospheric plasma, and pulsed electric field), novel virucidal surfaces, and bioactive compounds are examined for their potential to inactivate viruses on the surfaces of foods or food contact surfaces (tools, equipment, hands, etc.). Every disinfection technique is discussed based on its efficiency against viruses, specific advantages and disadvantages, and limitations. Structure, genomic organization, and molecular biology of different virus strains are reviewed, as they are key in determining these techniques effectiveness in controlling all or specific foodborne viruses. Selecting suitable viral decontamination techniques requires that their antiviral mechanism of action and ability to reduce virus infectivity must be taken into consideration. Furthermore, details about critical treatments parameters essential to control foodborne viruses in a food production environment are discussed, as they are also determinative in defining best disinfection and hygiene practices preventing viral infection after consuming a food product.     

Enhanced photocatalytic and antifungal activity of ZnO–Cu2+and Ag@ZnO–Cu2+ materials

Zinc oxide is one of the most versatile nanostructured materials with a broad range of applications. Besides, its physicochemical properties can be tuned easily by synthesis conditions to be optimal for a specific application. In our group, we aim for the production of visible light-active materials with enhanced antimicrobial activity. Thus, we synthesize ZnO–Cu²⁺and Ag@ZnO–Cu²⁺ by using a fast and robust microwave solvothermal reaction. We investigate the limit of solubility of Cu²⁺into ZnO lattice producing Cu doped ZnO materials with different doping levels (1, 2, 3, 4, and 5 at. %, Cu/Zn). We also investigate the role of the copper precursor, using copper(II) acetate or copper(II) sulfate as model precursors. Copper acetate incorporates more efficiently into ZnO lattice by decreasing the Eg value of the doped materials at low doping levels. Furthermore, we study the composites Ag@ZnO–Cu²⁺ aiming to reduce doping levels and to improve antimicrobial activity. Characterization of the materials by different techniques demonstrates their uniform size, purity, crystallinity, and visible light activity. In this study, we evaluate airborne fungal contamination and demonstrate the capacity of ZnO–Cu²⁺ and Ag@ZnO–Cu²⁺ to inhibit fungal growth. We studied the microbiological quality of indoor air (vivarium) by sampling air under different conditions. By sampling air with a photocatalytic prototype, the amount of fungi in the air decreases considerably, particularly fungi that can enter the lung. In addition, ZnO–Cu²⁺ shows excellent antifungal activity against Candida sp at low doses. We use Atomic force microscopy (AFM) and holotomographic microscopy (HTM) to provide further evidence on the capacity of the prepared materials to achieve effective damage to fungal cells and to inhibit biofilm formation.     

Evidence for alternative exhaled elimination profiles of disinfection by-products and potential markers of airway responses to swimming in a chlorinated pool environment

Chlorine-based disinfectants protect pool water from pathogen contamination but produce potentially harmful halogenated disinfection by-products (DBPs). This study characterized the bioaccumulation and elimination of exhaled DBPs post-swimming and investigated changes in exhaled breath profiles associated with chlorinated pool exposure. Nineteen participants provided alveolar-enriched breath samples prior to and 5, 90, 300, 510, and 600 minutes post-swimming. Known DBPs associated with chlorinated water were quantitated by thermal desorption-gas chromatography-mass spectrometry. Two distinct exhaled DBP elimination profiles were observed. Most participants (84%) reported peak concentrations immediately post-swimming that reduced exponentially. A sub-group exhibited a previously unobserved and delayed washout profile with peak levels at 90 minutes post-exposure. Metabolomic investigations tentatively identified two candidate biomarkers associated with swimming pool exposure, demonstrating an upregulation in the hours after exposure. These data demonstrated a hitherto undescribed exhaled DBP elimination profile in a small number of participants which contrasts previous findings of uniform accumulation and exponential elimination. This sub-group which exhibited delayed peak-exhaled concentrations suggests the uptake, processing, and immediate elimination of DBPs are not ubiquitous across individuals as previously understood. Additionally, non-targeted metabolomics highlighted extended buildup of compounds tentatively associated with swimming in a chlorinated pool environment that may indicate airway responses to DBP exposure.     

Inactivation of particle-associated viral surrogates by ultraviolet light

This study investigated whether colloid-sized particles can enmesh and protect viruses from 254-nm ultraviolet (UV) light and sought to determine the particle characteristics (e.g. size, chemical composition) that are most relevant in causing a protective effect. Two viral surrogates (MS2 coliphage and bacteriophage T4), three types of particles (kaolin clay, humic acid powder, and activated sludge), two coagulants (alum and ferric chloride), two filtration conditions (none and 0.45 microm), and two UV doses (40 and 80 mJ/cm2 for MS2 coliphage; 2 and 7 mJ/cm2 for bacteriophage T4) were considered in a series of bench-scale UV collimated beam experiments. Transmission electron microscopy was used to qualitatively confirm the phage particle-association after coagulation. Humic acid and activated sludge floc particles shielded both viral surrogates to a statistically significant degree (with >99% confidence) relative to particle-free control conditions, while the kaolin clay particles provided no significant protection. The results of the study suggest that particles <2 microm in diameter are large enough to protect viruses from UV light and that particulate chemical composition (e.g. UV-absorbing organic content) may be a critical factor in the survival of particle-associated viruses during UV disinfection.     

离子色谱法测定水中的卤代乙酸和卤素含氧酸

采用离子色谱法对饮用水中的3种卤代乙酸、3种卤素含氧酸和F^-、Cl^-、NO3^-、SO4^2-进行了检测,该方法对饮用水中6种消毒副产物的最低检测限为2.96～26.26μg/L,加标回收率为87.57%～105.09%.     

空调系统生物污染防治方法概述

介绍了微生物的种类、习性特点及常用灭除方法 ,并结合HVAC系统的具体应用要求 ,探讨了空调系统可能采用的一些生物污染灭除方法。     

膜法在水处理中的优势及应用

通过介绍膜分离技术在水处理中的应用，从技术、经济、运行管理三个方面说明了膜法相对于目前的常规处理方式的比较优势：安全饮用水保障技术是提高人民生活水平的前提；膜处理法能获得高质量的饮用水。还从经济、运行管理两个方面说明膜法是水处理和水工业的发展方向，是“21世纪的水处理技术”。最后，还阐述了膜法在水处理技术中的现状及发展前景。     

浅析饮用水中氯化消毒副产物的控制

从饮用水中消毒副产物(DBPs)的种类,及其对人体健康的影响方面,综述了DBPs的控制现状以及前景,分析了几种对DBPs前体物及其DBPs的去除方法,讨论了它们的运行效果,展望了今后饮用水安全消毒的前景,从而将其危害降至最低。