Survival and Growth of Salmonella hadar on Minimally Processed Cabbage as Influenced by Storage Abuse Conditions

Shredded, washed and centrifuged cabbage was packaged in monooriented polypropylene (OPP) bags, inoculated with Salmonella hadar and stored 10 days at 4°C, 12°C and 20°C. Microbiological, appearance, odor and headspace gas analysis were evaluated throughout storage. S. hadar and mesophilic aerobic and psychrotrophic microorganism growth was affected by storage time and temperature. S. hadar counts were lower (p<0.05) at 4°C than at 12°C and 20°C. The score ratings for general appearance, wilting, browning and off-odor showed that all samples were commercially acceptable. Results indicated that S. hadar could survive and proliferate on minimally processed cabbage, thereby posing a potential hazard to consumers.     

豆腐衣制备新工艺

研究了豆腐衣制备的传统工艺，并确定了豆腐衣的品质指标。研究开发出豆腐衣生产新工艺：大豆脱皮后制粉，以食用酸进行等电聚沉，沉淀物回调ｐＨ值至７．５～８．０，胶磨加热后制成豆腐衣；酸浸最佳工艺参数是：１１５加水量，５０℃浸提１０ｍｉｎ；成形最佳工艺参数是：金属表面温度１１０℃，２０％料液比，成形时间２．５ｍｉｎ．营养成分分析结果表明：新工艺使大豆蛋白利用率由传统工艺的５０．８％提高至９８．７％，脂肪利用率由５４．１％提高至９９．１％，碳水化合物利用率由２４．４％提高至６１．０％．     

钙和褐变抑制剂对鲜切菠萝影响的初步研究

研究的目的是筛选对鲜切菠萝颜色和硬度有重要影响的因子。试验采用正交设计,使用浓度为0%和0.5%的异抗坏血酸钠、柠檬酸、六偏磷酸钠、EDTA和氯化钙溶液浸泡菠萝扇片3分钟,振干表面溶液后用聚苯乙烯塑料托盘装(每盘5片,每片约25g)并用PVC膜包扎密封,在10℃下贮藏7天;分别在处理后的第1天和第7天测定菠萝片的L*、a*、b*和硬度。结果表明,在α=0.05水平下,只有异抗坏血酸钠显著抑制L*、a*、b*值的变化;所有5种试剂对鲜切菠萝硬度的影响均不显著。     

Review of sodium analysis proficiency test results

Proficiency testing results for sodium analysis in foods raised concerns over the proportion of laboratories achieving satisfactory z-scores. Test materials for sodium analysis include fruit juice, canned meat meal, tomato sauce, cheese and pasta meal, and snack food. Fruit juice and tomato sauce data sets are the most problematic in deriving the assigned value with sufficiently low uncertainty to provide evaluative z-scores. The standard deviation for proficiency is derived from Horwitz, with a lack of collaborative trial data for these matrices to provide other guidance. The status of accreditation for the method/matrix does not appear to influence the observed variation in results. Microwave digestion is much less commonly used than simple acid digestion. The choice of determination method appears to be entirely matrix dependent (whether flame atomic absorption spectroscopy, flame photometry or inductively coupled plasma spectroscopy). Results for juice matrix may be overestimated if flame photometry is used, due to either potassium interference or careless reporting where potassium is also determined.     

Mass transfer ways of ultraviolet printing ink ingredients into foodstuffs

The case of isopropylthioxanthone (ITX) showed conclusively that the ingredients of ultraviolet printing inks may migrate into packaged foodstuffs. For multilayered materials like beverage cartons, the only way that mass transfer can occur is by the so-called set-off effect. In contrast, in the case of rigid plastics like yoghurt cups, two other methods of mass transfer, permeation and gas phase, have to be considered. In cooperation with producers of ink, plastic cups and yoghurt, a project was conducted in order to elucidate the mass transfer of ink ingredients. In addition, the influence of storage time and the age of ultraviolet lamps on the migration level was examined. The suitability of 50% ethanol as a simulant for yoghurt was also tested. ITX was chosen as a model migrant, as it is easily detectable. Furthermore, the migration of two other substances, the photo-initiator 2-methyl-4′-(methylthio)-2-morpholinopropiophenone (MTMP) and the amine synergist ethyl-4-(dimethylamino)benzoate (EDAB), which may be used in combination with ITX, was studied. Before being filled with yoghurt or 50% ethanol, the printed cups were stored under different contact conditions, with and without contact between the inner layer and the printed surfaces, in order to distinguish between the possible mass transfer ways. All analyses were performed by means of high performance liquid chromatography with diode array and fluorescence detection (HPLC-DAD/FLD). It was shown that contamination with ITX and EDAB occurs via set-off and that the degree of migration increases with lamp age and storage time of the unfilled cups. Migration of MTMP was not detectable. The results show that besides the careful selection of the appropriate raw materials for printing ink, a close monitoring of the process also plays a major role in migration control. In addition, the results proved that 50% ethanol is a suitable simulant for yoghurt.     

Further insights into the mechanism of migration from the PVC gaskets of metal closures into oily foods in glass jars

Factors influencing migration from the gaskets of metal closures into oily foods were investigated. Tightening of the lid has an effect presumably through the deformation of the gasket, the amount of oil adhering to the latter, and the proportion of its surface being covered by oil. The substantial difference observed in the migration determined with the jar in an upright or a reversed position is partly related to this. The nature of the plasticizer determines the saturation in the partitioning process between the gasket and the small amount of oil in contact with the gasket as well as the adherence of oil (wettability). If saturation is rapidly reached, the frequency of exchanging the oil by shaking of the jar is an important factor. A complete exchange of the oil in contact with the gasket requires vigorous and persisting shaking, presumably because of the high viscosity and the hindered access to the angle between the gasket and the jar rim. The limited data available on long-term performance suggest that migration accelerates after roughly one year of storage. It is concluded that the extrapolation of long-term migration from short-term data presupposes a deeper investigation of the course of migration over years.     

Effect of different starches on rheological and microstructural properties of (II) commercial processed cheese

A range of commercial processed cheese samples containing starch were prepared on a Rapid Visco Analyser (RVA) and on a pilot plant scale. This work clearly demonstrated that it was possible to manufacture processed cheese with part of the protein replaced with potato starch, while maintaining similar rheological attributes (firmness) to those of the control and an acceptable melt index. Sensory evaluation showed that, although the reduced‐protein cheese samples had a good, clean, fresh flavour that was comparable with that of the control, at high starch concentrations the starch‐containing processed cheese had a pasty texture and tended to stick to the wrapper.     

高温深井裂缝性泥灰岩压裂技术

华北束鹿凹陷泥灰岩的主要特点有：①深井（4237．5m）、高温（146℃）、高压（42MPa）；②高泥质含量（占岩石的15％～22％），黏土矿物中运移矿物含量高（占黏土的54％～71％）；③水平层理异常发育，并伴随高角度缝洞；④基质特低渗（0．0087-0．022mD），可动流体饱和度特低（12．3％～18．3％）。针对泥灰岩储集层特点，提出了水力压裂技术系统：①新型的“超级”瓜尔胶体系；②不同粒径组合的高强度陶粒；③新型的小型测试压裂技术；④新型的压裂工艺参数优化及施工技术，如压裂工艺参数的多级优化技术、多裂缝控制技术等；⑤新型的压裂后放喷及排液技术。将上述技术应用于晋古13井，压裂取得了理想的效果，初步形成了泥灰岩储集层的水力压裂技术体系。图11表2参12     

合肥正大购物广场中央空调方案设计

中央空调系统对大型商业综合体的使用,工程造价及日后的运行费用至关重要,中央空调方案包括空调冷、热源,空调形式等,以往空调方案的比较都集中在空调冷热源及其经济性,就空调的主要形式,比如是否采用温湿度独立控制等分析较少;对空调运行可靠性分析也较少。就合肥地区一大型商业综合体的中央空调方案,包括空调形式的设计做出分析,并得出最终空调形式与建议。