Dual bacterial strains TTI for monitoring fish quality in food cold chain

Most microbial time–temperature indicators (TTIs) considered only one spoilage strain. This research compared single and dual spoilage strains-based microbial TTI for quality changes of chilled grouper fish (Epinephelus fuscoguttatus x E. lanceolatus) fillet products during distribution. The next-generation sequencing (NGS) and traditional plate count approach showed that Pseudomonas fragi and Vibrio parahaemolyticus were specific spoilage bacteria at 7 and 15°C. A dual-strain TTI response provides more accurate results than a single-strain TTI and provides an irreversible color change from yellow to reddish-brown, showing levels of fish freshness. The microbial TTI comprises fish spoilage bacteria strains with 3 log CFU/ml, a nutrient broth supplemented with 2% NaCl as a medium, and phenol red with 0.25 mg/ml as a pH indicator. Overall, this study points to the applicability of a dual-strain microbial TTI as a valuable tool for monitoring fish quality changes during cold chain break condition.     

Development of a prototype of a colourimetric temperature indicator for monitoring food quality

Temperature greatly affects the food quality and safety. Temperature control is an important condition during distribution and storage. An intelligent and biodegradable temperature indicator packaging material was developed based on a natural and heat-sensitive pigment (anthocyanin – ATH). Different concentrations of ATH were incorporated into chitosan matrix films (2.00%, w/w) that were applied as a surface coating on card paper, forming the chitosan card paper system (CH-Sys). The novelty of this work is an alternative packaging material that is biodegradable, simple manufacturing and indicates temperature variations in a specific range by irreversible visual colour changes. The CH-Sys changed irreversibly the colour from light violet to light yellow in response to different temperature exposition (40 °C until 70 °C), independently of luminosity (0 or 1000 lx). The results indicated that the CH-Sys has a great potential for use as a temperature indicator prototype in the specific temperature range studied in this work.     

冷链食品病毒控制及其次生危害研究进展

与常规微生物相比, 病毒能在干燥、冷藏和冷冻等恶劣条件下长期存在并保持传染性, 而冷链食品具有全程低温及长途运输的特点, 这使得冷链食品成为全球范围内病毒大面积传播的风险点, 因此, 对冷链食品进行全面消毒也成为控制病毒传播的重要环节。本文围绕冷链食品生产-加工-运输的全链条, 对当前报道的冷链食品病毒传播情况进行了总结, 重点介绍了在低温条件下用于病毒控制的常用化学方法和紫外线照射、电离辐照及低温等离子体等物理方法, 分析阐述了其消毒作用机制、消毒效果及消毒过程中可能产生的次生危害, 为食品安全防控领域从微生物污染防控向病毒污染防控的转变提供理论依据, 为采取科学合理的消毒方式实现对冷链食品病毒传播的控制提供参考。     

国内外食品冷链物流关键环节温控要求对比研究

目的 研究国际组织和其他国家对食品冷链温度要求的管理情况,为我国冷链标准完善和今后研究方向提出建议。方法 将我国标准与国际食品法典委员会、国际标准化组织、欧盟、美国、加拿大、澳大利亚和新西兰标准的相关规定进行对比分析,提出关注和重点考虑的问题以及对我国冷链物流温度控制的建议。结果 国外基本为推荐性操作要求,较少规定具体温度,我国标准体系为强制性和推荐性相结合,对温度要求较为具体。国内外标准中都允许温度波动,同时强调车辆预冷、监控、运输工具等的重要,但国外标准更多注重过程管理。提示我国今后要加强操作规范,尤其是推荐性标准的制定。结论 我国食品冷链物流关键环节的温度要求与国际基本接轨,安全标准制定相对合理和完善,应加强推荐性操作规范标准的制定,促进行业健康和谐发展。     

以先进的冷链构建全程的食品安全模式

<正> 近年来我国食品安全事件层出不穷,人们逐渐清晰地认识到食品安全依赖控制,而非检测。因为基于有限标准和指标的检测无法完全保障食品的安全,也没有任何一个国家有能力为每一件产品把关。所以,要解决食品安全问题,必须将防控前移,从农业源头抓起,加强食品供应链的双向控制,即从"农田到餐桌"的全程质量控制系统和"从商品到源头"的可追溯系统,这才是     

A simulation approach for optimal design of RFID sensor tag-based cold chain systems

This study introduced a systematic approach for assessing alternative operational models and to determine optimal values for some of the core design parameters in an RFID sensor tag-based cold chain system. First of all, we defined an RFID and sensor data collection and storage model. Next, we developed an RFID sensor tag-based cold chain simulation model and a simulator based on Discrete Event System Specification (DEVS) formalism. Finally, based on a case study, we demonstrated a procedure for determining the optimal sensing interval value with the proposed simulator. The results from the case study have shown that the proposed approach presents important advantages to analyze the Key Performance Indicator (KPI) of cold chain systems according to changes of RFID sensor tag-based cold chain system’s operation models and parameter values.     

Water dynamics and microbial communities of bigeye tuna (Thunnus obesus) during simulated cold chain logistics

This study investigated changes in the physicochemical indexes, water dynamics, and microbial communities of bigeye tuna (Thunnus obesus) during simulated cold chain logistics. With increasing storage time, the color and water activity decreased gradually, while drip loss gradually increased, and pH increased with a fluctuating pattern. The trend of bound water content was not obvious, trapped water declined, and free water increased with fluctuations over time, according to low-field nuclear magnetic resonance (LF-¹H NMR). High-throughput sequencing results indicated that fluctuating temperatures inhibited Acinetobacter and Pseudomonas and promoted Pelomonas, Psychrobacter, and Shewanella. Principal component analysis and redundancy analysis revealed significantly different microbial community interactions among the four groups, and environmental factors had distinct effects on bacterial community assemblages. LF-NMR and high-throughput sequencing can be used to monitor dynamic quality changes in bigeye tuna during simulated cold chain logistics with fluctuating temperatures.     

基于物联网的冷链食品安全监控系统的设计与实施

为实现冷链食品的安全管理与预警,设计了基于物联网技术的冷链食品安全监控系统.该系统通过传感器、射频识别、全球定位系统等物联网技术,实现冷链食品信息的自动采集、传输和处理,从而实现冷链食品的安全监控及预警管理.鉴于该系统的推广还面临许多问题,应加快物联网标准体系建设,加快RFID及传感器等关键技术的开发研究,形成具有自主知识产权的物联网技术核心,高度重视物联网发展带来的安全问题,积极引导行业示范应用,以推动基于物联网技术的食品安全监控系统的快速发展.     

用于食品冷冻温度控制的模糊控制系统设计

目的:提高食品进入冷冻隧道的速度控制回路和温度控制回路的设定值调整能力。方法:对传送带速度和温度控制回路进行了单独处理,设计用于食品冷冻温度控制的模糊控制系统。该控制系统包括用于食品传送带滚子转速的比例—积分—微分控制器、用于冷冻隧道温度调节的比例—积分控制器,并采用Takagi-Sugeno模糊控制器来设定温度调节比例—积分控制器的温度设定点。结果:待冷冻食品的质量流量从650 kg/h增加到700 kg/h、驱动辊的转速从1.62 r/min增加到1.75 r/min时,最终食品温度可快速恢复到约-18℃;食品入口发生+5℃的温度干扰时,模糊控制器动作,从而将食品的出口温度保持在预期值-18℃附近。结论:所设计的控制系统通过选择允许快速响应和相对较低超调的系统参数,可实现输出变量的值不会在设定值附近出现大幅波动。     

Development of a predictive program for microbial growth under various temperature conditions

A predictive program for microbial growth under various temperature conditions was developed with a mathematical model. The model was a new logistic model recently developed by us. The program predicts Escherichia coli growth in broth, Staphylococcus aureus growth and its enterotoxin production in milk, and Vibrio parahaemolyticus growth in broth at various temperature patterns. The program, which was built with Microsoft Excel (Visual Basic Application), is user-friendly; users can easily input the temperature history of a test food and obtain the prediction instantly on the computer screen. The predicted growth and toxin production can be important indices to determine whether a food is microbiologically safe or not. This program should be a useful tool to confirm the microbial safety of commercial foods.     

猪肉冷链加工与物流微生物危害分析与控制

基于微生物危害分析,测试冷却分割猪肉冷链加工与物流过程的微生物数量和温度分布,明确关键污染环节和物流过程温度波动,建立关键控制点及其控制措施,制定冷却猪肉冷链加工与物流HACCP计划,提出重点改善卫生管理和温度监控措施,使产品微生物数量控制在可接受水平,确保加工流通过程产品质量安全。     

Rapid separation and counting of viable microbial cells in food by nonculture method with bioplorer, a focusing-free microscopic apparatus with a novel cell separation unit

A nonculture method utilizing a novel apparatus, the bioplorer, was developed. The bioplorer is composed of an efficient cell separation unit, a focusing-free microscopic device, and an image analysis program. A meat or vegetable suspension is poured into the cell separation funnel, and insoluble matter in the sample suspension is trapped by prefilters. Microbial cells passing through the two prefilters are then trapped by the membrane filter (pore size, 0.4 microm). Trapped cells are double-stained with 4',6'-diamidino-2-phenylindole and propidium iodide, and the membrane filter is removed and set on the focusing-free microscope. A fluorescent image is then recorded. Total numbers of viable and dead cells on the membrane filter can thus be determined automatically. One assay can be performed within 10 min, which is much faster than the culture method. The results obtained with both the nonculture method and the culture method for meat and vegetable samples were highly correlated (r = 0.953 to 0.998). This method is feasible for the practical purpose of food safety control.     

Development of a microbial Time Temperature Indicator for monitoring the shelf life of meat

Time Temperature Indicators (TTIs) constitute smart devices through which the full history of the time-temperature profile of a food is monitored. The objective of the current study was to develop a versatile microbial TTI based on the violacein formation, a violet pigment produced by the microorganism Janthinobacterium sp. during early growth, depending on temperature and intrinsic properties of the growth medium. The TTI system consisted of Tryptic Soy Agar enriched with 1% glycerol, spot-inoculated with the bacterium. Input parameters were the storage temperature, the pH of the medium, the initial concentration of the microorganism and the volume of the spot. Image analysis was used to estimate the color change of the spots. Luminosity (L^⁎) parameter described the color change adequately. The Baranyi model was used to fit the violacein kinetics data (L^⁎ curve) estimating the TTI's endpoint, i.e., the time at which the violet color occurred. Survival analysis was used to analyze the endpoint data assessing the activation energy, E_a^TTI, and the TTI's endpoint at a reference temperature (t^TTI,ref_endpoint). The E_a^TTI and t^TTI,ref_endpoint (T_ref = 0 °C) parameters ranged between 65.1–110.3 kJ/mol and 10.1–107.6, respectively. Based on the estimated E_a^TTI and t^TTI,ref_endpoint parameters, a decision can be made on the most suitable combination of pH, initial concentration and spot quantity for monitoring the impact of time-temperature profile of different foods on the occurrence of spoilage. The TTI was validated for spoilage of minced beef meat under isothermal and dynamic storage conditions using data generated in this study. The applicability of the TTI was also evaluated to other meat products, including vacuum packaged cooked meat products, using literature data.     

Near-infrared spectroscopic monitoring of biomass, glucose, ethanol and protein content in a high cell density baker's yeast fed-batch bioprocess

The use of at-line NIRS to monitor a high cell density fed-batch baker's yeast bioprocess was investigated. Quantification of the key analytes (biomass, ethanol and glucose) and the product quality indicator (percentage protein content) was studied. Biomass was quantitatively modelled using whole matrix samples (as was percentage protein content). The dominance of the whole matrix spectrum by biomass, and its associated light scattering effects, were overcome by use of filtrate samples and adapted (semi-synthetic) filtrate samples, which allowed successful ethanol and glucose modelling, respectively. Calibrations were rigorously challenged via external validation with large sample sets relative to the calibration sample size, ensuring model robustness and potential practical utility. The standard errors of calibration for biomass, glucose, ethanol and total intracellular protein were (g/l) 1.79, 0.19, 0.79 and 0.91, respectively, comparable to those of the primary assays. The calibration strategies necessary to generate quantitative models for this range of analytes in such a complex high cell density bioprocess fluid are discussed.     

北京2008年奥运食品冷链物流能特点浅探

2008年奥运会将在北京举行，作为全球瞩目的体育盛会，它的成功举办将对弘扬中华文化、促进世界和谐做出巨大贡献。作为奥运会保障体系的物流系统显得十分重要，尤其是食品冷链物流在这次奥运物流中具有特殊的含义。为建立一个完整科学的奥运食品冷链物流系统，保证奥运食品冷链物流的畅通安全，考虑到食品冷链物流的固有特点和奥运物流需求的独特特征，     

基于网络拓扑的生鲜食品供应链管理的无线传感器网络设计

基于ZigBee标准无线传感器网络(WSN),开发设计了一套实时生鲜食品供应链监控系统,并改进了综合传感器的可配置架构和网络交换方案。从性能方面对192个终端设备的树型拓扑无线传感器网络系统和80个终端设备的星型拓扑无线传感器网络系统进行了实现和评价。测试结果表明,数据通信的成功率在99%以上,理论分析和实际测量的结果表明,终端设备的功能及寿命足以满足供应链监控的应用。     

Development of an l-rhamnose bioluminescent microbial biosensor for analysis of food ingredients

A bioluminescent microbial biosensor induced specifically by l-rhamnose was developed and optimized, to monitor food processes where pectin is involved. The biosensor was developed by fusing the Escherichia coli promoter P_rhaB to the promoterless luxCDABE genes of Vibrio fischeri within plasmid pUCD615. Escherichia coli carrying this construct responded positively to l-rhamnose, but, because of low reporter signal, the enhancement of bioluminescence levels was required. The response was improved by promoter region length manipulation and resulted in 86-fold increase in response ratio. The specificity of the biosensor (80 times higher ratio response to l-rhamnose compared to other carbohydrates) and quantitative response to the target analyte were confirmed. The potential of this biosensor to monitor the hydrolysis of various types of pectin was demonstrated and a calibration curve was acquired. Our study presents a novel l-rhamnose-inducible microbial biosensor as a fast and economical alternative to chemical methods of pectin analysis.     

A novel approach to evaluate the temperature during drying of food products with negligible external resistance to mass transfer

The paper deals with modeling the convective drying process. A relevant and reliable mathematical model that captures the history and distribution of temperature is presented. The attention is focused on the simultaneous heat and mass transfer occurring during drying where dry and hot air flows about the food. In the present study, external resistance to mass transfer is considered negligible. As a result, the drying curve is almost independent of the boundary conditions, which means that drying is diffusion-controlled. The main connotation of present study regards to undertake analytical procedure to establish the novel model for practical applications. The results show that the temperature evolution can be evaluated from an advanced analytical solution in a quick and efficient manner. The model is validated with the literature experimental data obtained for carrot and mango slabs. A good agreement is obtained between the model predictions and the available experimental results.