Automated fluorimetry in quality control of pasteurized and ultra-high temperature-treated starch soup

Automated monitoring of the microbiological quality of heat-processed foods by the resazurin reduction test was applied to microtitration plate incubator-fluorimeter technology. The appearance and disappearance of the fluorescing peak of resorufin was monitored on microtitration trays. Pasteurized or ultra-high temperature-treated starch-based soup was used as the model food system. Bacillus subtilis spores (ultra-high temperature treatment) and vegetative cells of Enterococcus faecalis (pasteurization) were inoculated into the soup before the heat treatment at levels which resulted in some survival. The timing of appearance of maximum fluorescence correlated with the number of bacteria in pre-incubated samples. Automated resazurin-reduction fluorimetry was compared with conventional plating, turbidometry and microcolony count by the direct epifluorescent filter technique. The results of the resazurin test correlated well with those of all the other methods tested. Fluorimetry had the advantage that the results could be read within 1–5h and the reproducibility was superior to the other methods.     

全链路成像光谱仪信噪比仿真

研究成像光谱仪优化问题,由于光谱成像受到环境噪声影响,传感器精度达不到要求,传统信噪比优化仿真方法,通常只考虑传感器本身的特性,没有综合考虑地物的光谱特性、辐射传输对其影响,导致传感器信噪比很难满足要求。为消除噪声提出了全链路成像光谱仪信噪比仿真方法,以叶面积指数反演应用为背景,从地面植被反射率信号出发,考虑大气辐射传输和传感器能量转换过程,建立了全链路成像光谱仪信噪比仿真模型,并通过具体实例进行验证和分析。理论分析和仿真结果表明:方法是对成像光谱仪信噪比仿真的一种全新而有益的尝试,具有很好的扩展性,传感器的研制设计提高性能指标,并缩短研制周期,为设计提供了参考。     

基于机器视觉的机加工缺陷检测系统设计

本文设计了一个基于机器视觉的机械加工缺陷检测与定位系统,着重阐述了该系统的工作原理,讨论了相关的图像处理、检测及识别算法,仿真实验均用MATLAB编程实现,仿真结果证明了该方法的可行性.采用该方法能够有效的检测、定位并识别出工件表面的缺陷.     

Application of rapid methods and ultrasound imaging in the assessment of the microbiological quality of aseptically packed starch soup

The application of rapid microbiological methods such as automated turbidometry and microcolony count using the direct epifluorescence technique (DEFT) was tested for the quality control of aseptically packed ultra-high temperature-treated starch-based soup. In addition, a non-destructive method using ultrasound imaging through the packages prior to the microbiological analysis was evaluated. The results showed that ultrasound could be a promising non-destructive testing method in quality control schemes for starch-based foods. Certain problems associated with calibration may arise in the application of turbidometry for heat-treated food material. Neither method studied in this work was sufficiently sensitive without a pre-incubation step.     

BACTERICIDAL EFFICIENCIES OF COMMERCIAL DISINFECTANTS AGAINST LISTERIA MONOCYTOGENES ON SURFACES

The efficiencies of potassium persulphate, isopropanol, hydrogen peroxide and peracetic acid, quaternary ammonium compound, hypochlorite, sodium dichloroisocyanurate, ethanol and phenol derivatives, tertiary alkylamines and dimethyl alamine betaine-based disinfectants and a hypochlorite-based disinfecting cleaning agent were evaluated against eight Listeria monocytogenes strains representing three different ribotypes. All the disinfectants were effective in a suspension test with an exposure time of 30 s at the lowest concentrations recommended by the manufacturer. The efficiencies on surfaces were reduced. However, on clean surfaces all the agents were considered effective when the exposure time was 5 min and the concentration was the average recommended by the manufacturer. Five of nine disinfectants and the disinfecting cleaning agent were considered effective in soiled conditions in the surface test. The most efficient agent was isopropanol-based and the least effective was the disinfectant containing tertiary alkylamine and dimethyl alamine betaine. Differences in bactericidal efficiencies of disinfectants against different L. monocytogenes strains on meat soiled surfaces were found.     

油房沟水电站不良地质段的斜井开挖

云南省昭通油房沟水电站压力管道斜井处于不良地质段,受不良地质的影响,在开挖过程中多次塌方,开挖方法多次更改,简要介绍斜井开挖施工过程。     

THE EFFECTS OF ALTITUDE ON FRUIT QUALITY AND COMPRESSION LOAD FOR CRACKING OF WALNUTS (Juglans regia L.)

Nuts of walnut (Juglans regia L.), cultivated in the district of Denizli (altitude of 300 m) and Cameli (altitude, 1200 m) in the Aegean region of Turkey, were used to determine the effects of altitude on fruit quality and the force and energy required to crack the nuts. The varieties used were Bilecik, Sebin, Yalova‐1, Yalova‐3 and Yalova‐4. For all cultivars, walnut trees grown at the higher altitude produced small size nuts with thick shells. Based on the average for all cultivars, kernel removal quality decreased with high altitude. The nuts obtained from the high‐altitude location were lighter‐colored and required more force to fracture the nuts than those harvested at the low altitude. The amount of energy required to crack the nuts was higher for the nuts grown at the low‐altitude location except for the cultivar, Sebin.     

Use of Photobacterium leiognathi in studies of process equipment cleanability

The aim of the EC funded Project AIRI-CT-92 is to develop methods for the cleanability testing of food processing equipment. Photobacterium leiognathi ATCC 33469 has been suggested as an indicator organism in cleanability testing. Here, this bacterium was grown as a biofilm for 5 h or 24 h at room temperature on various surfaces, clean or milk-soiled, by immersing the surfaces in luminous medium inoculated with P. leiognathi. The surfaces were then rinsed or cleaned using a CIP procedure before the hygienic status was determined using conventional plating, bioluminescence output and image analysis.
Rinsing did not eliminate the bacterium from the surfaces nor did the CIP procedure when 24-h biofilms were used, as was readily seen after enrichment in luminous medium. In image analysis the biofilm showed a spotlike growth pattern which was most evident on stainless steel. The advantage of P. leiognathi in the cleanability assessment, which is based on the natural light output of the test bacterium, is that the test is easy to perform and can be carried out without use of expensive reagents.