THE EFFECT OF AEROBIC MESOPHILIC MICROFLORAL LEVELS ON THE ISOLATION OF INOCULATED LISTERIA MONOCYTOGENES STRAIN LM82 FROM SELECTED FOODS

The effect of aerobic mesophilic microfloral concentration on the isolation of Listeria monocytogenes LM82 was studied in 31 (18 cheeses and 7 noncheese) retail foods having standard plate counts of 10¹ to 10⁸ colony forming units (CFU)/g. Foods were spiked with L. monocytogenes and enriched at 30°C for 24 h in a selective enrichment broth used in a U.S. Food and Drug Administration method. Inoculum levels for isolation on modified McBride agar ranged from 0.1 to > 5 × 10³ with a geometric mean value of 5 inoculated CFU/g or 1.4 CFU/g. Pure Enterococcus (Streptococcus) faecalis ( 0 to 6 × 10⁶ inoculated CFU/mL ) in the absence of food matrix had no effect on the enrichment of L. monocytogenes. Ease of isolation of LM82 was independent of the food microflora concentration both generally and in the specific food type of 9 Brie cheeses. Competition, when it occurs, therefore, may be due to specific bacterial competitors rather than bacterial numbers .     

Power,Discursive Space and Institutional Practices in the Construction of Housing Problems

A constructionist approach to the study of social problems and housing policy provides a theoretically informed means of analysing the ways in which housing policy is formulated and implemented. Yet despite a strong commitment by housing researchers to policy relevance, constructionist studies of how specific social problems are generated and deployed have so far made only a limited impact on housing research. The paper addresses this lacuna by first discussing important literature and the key conceptual issues in this field of study. This is followed by a discussion of two examples from recent UK housing policy (the shift in the 1980s from defining lone mothers as the victims of housing shortages to a morally questionable group subverting needs-based allocation policies and the re-emergence of anti-social behaviour as a problem on housing estates). The paper's conclusion is that the 'construction of problems' provides a rich source of new material as well as offering significant opportunities to develop a more critically informed housing research agenda.     

Response of Shiraz grapevines to five different training systems in the Barossa Valley, Australia

Own‐rooted Shiraz, spaced 1.5 m apart in 2.75 m wide rows, were compared under five different training systems in the Barossa Valley, South Australia over five seasons starting 1995–96. Our objective was to determine how training affected fruit composition and crop yield in a context of efficient vineyard management. Training systems were: (i) low single wire (LSW), in which vines were trained to bi‐lateral cordons, 1.0 m above the ground, non‐shoot‐positioned; (ii) high single wire (HSW), a higher cordon (1.8 m) version of LSW; (iii) vertically shoot positioned (VSP); (iv) Scott Henry, where canopies of alternate vines were cordon‐trained and shoot‐positioned upwards (SHU) or downwards (SHD); and (v) minimally pruned (MIN), the same as LSW, except vines were not annually spur‐pruned. Crop yields (kg/m of row), over four seasons, averaged 4.9 (MIN), 2.9 (combined Scott Henry), 3.2 (VSP), 2.6 (HSW) and 2.9 (LSW). The greatest year‐to‐year variation in yield occurred with MIN and Scott Henry training. Crop weight of SHD vines was inferior to that of SHU vines in two seasons due to fewer shoots and bunches per vine, and to fewer bunches per shoot. Individual berry weights (g) were consistently least with MIN (0.89), and greatest with VSP (1.17). Fruit from all training systems exhibited similar rates of sugar accumulation during two seasons in which repeated measures of fruit maturation were made. Excepting the relatively light yields observed in 1999–2000, sugar accumulation was delayed in MIN vines, relative to other training systems, even when MIN harvest was delayed up to two weeks. The delay is most readily explained by the greater crops of MIN vines. Berry total anthocyanins and total phenolics concentrations (mg/g berry fresh wt.) at harvest were not greatly affected by training system. Berry anthocyanins and total phenolics exhibited a negative relationship with crop/m of canopy and a slight positive relationship with bunch exposure when evaluated across all training systems. Experimental plot soil depth and water availability affected cane pruning weights, yield per vine, berry weight, and canopy characteristics. LSW, HSW and MIN training systems all provided good yields of high quality fruit, although MIN did have a tendency to produce excessive crops in some years. VSP and Scott Henry training were less attractive due to their inherently greater canopy management requirements.     

INHIBITION OF STAPHYLOCOCCUS AUREUS AND BACILLUS CEREUS ON A VEGETARIAN FOOD TREATED WITH NISIN COMBINED WITH EITHER POTASSIUM SORBATE OR SODIUM BENZOATE

Various amounts of nisin (0, 10³ and 5 × 10³ IU/g) in combination with either potassium sorbate (0, 2, and 3%) or sodium benzoate (0, 0.06 and 0.12%) were tested for effectiveness in inhibiting growth of Staphylococcus aureus C10 and Bacillus cereus B7 inoculated on a vegetarian food. The strains used were isolated from vegetarian foods obtained commercially in Taiwan, and the test food, spice and dried bean curd, was selected for the study based on ability to support the growth of these organisms. After treatment with a preservative combination, the surfaces of sterilized food samples were inoculated, samples were stored in vacuum or nonvacuum packages at either 4C or 30C, and at appropriate times, tested for microbial growth. Growth of both isolates was unaffected by vacuum-packaging treatment; however, a bacteriostatic effect was found at 4C. Data indicated that during the 14-day storage at 4C, vacuum-packaged samples treated with 5 × 10³ IU/g nisin and 0.12% sodium benzoate significantly (p < 0.05) decreased the counts of S. aureus C10 and B. cereus B7 by 2.61 and 3.02 log₁₀ CFU/g, respectively. In the vacuum-packaged samples treated with 5 × 10³ IU/g nisin and 3% potassium sorbate, counts for C10 and B7 were decreased by 2.35 and 2.64 log₁₀ CFU/g, respectively. Thus, the combined treatment extended the shelf-life of the vegetarian food .     

Fundamental Mass Flow Measurement of Solid Particles

A generic mass flow measurement device was developed as a variation on the theme of counting. In a hypothetical infinitely sparse mass flow, the number of passing particles could be counted in a time frame and multiplied by the mean mass per particle to obtain a mass flow per time unit. In a mass flow of realistic density, however, particles travel in cluster formation and direct counting of individual particles is impossible. If a method could be available that reconstructs the original number of particles in a cluster, the mass flow can be computed for realistic clustered mass flows. This reconstruction algorithm was developed in this research; it uses the measured cluster lengths to reconstruct the total number of particles in each passing cluster. The lengths of the clusters were measured with an optoelectronic device. The reconstruction algorithm was developed using simulation, augmented by clustering theory. For identical diameter particle flow, simulation results showed that the number of particles in a cluster could be reconstructed using a very simple reconstruction formula. This formula uses only the total number of clusters per time frame and the total number of individual particles measured in the same time frame. However, identical diameter flow is not realistic, since even identical particles are measured with a certain error. Reconstruction of the realistic distributed diameter particle flow was approximated using the identical particle method. The optical mass flow sensor has major advantages over traditional methods. It is virtually insensitive to vibrations, contamination, temperature drift, and misalignment and the underlying measurement concept is well understood. But most importantly, the sensor does not require calibration. The mass flow of identical particles (4.5 mm air gun pellets) was measured with an error smaller than 3% even for high density flow rates.     

PREDICTING CLEANING OF EQUIPMENT USING COMPUTATIONAL FLUID DYNAMICS

In the food industry, production lines are ideally run for very long time periods without the need for cleaning. A prerequisite is that the equipment and the line are hygienically designed. This means that there are no stagnant areas, crevices or other parts of the flow domain that may cause entrapment of the product that can subsequently lead to bacterial growth. However, unhygienic geometries such as those described are frequently encountered in practice, and more frequent cleaning is a necessity. This article reported modeling results validated with experimental work. Computational fluid dynamics was used to assess the cleanability of a T‐junction. Electrical conductivity measurements of a salt solution of known concentration before and after the T‐junction is cleaned using deionized water were reported. This comparison gives an acceptable qualitative agreement with finite volume‐based calculations that involve both steady‐state and transient operations. This approach is a necessary prerequisite for the development of models that will ultimately include bacterial growth and deactivation kinetics under processing conditions.     

美国阔叶木：现代生活典范——Tony Chi的世界

Tony Chi的设计目标是为这家新设于MCM Grand酒店的餐厅,营造简单、优雅、令人向往的气氛。餐厅的整体风格,是带出经典和精致的现代感觉,但轻柔的触感,也令空间变得舒适和吸引。酒柜前面的饰板外观优雅,由人手运用特别订造的胡桃木长板制作,坐在酒吧前的顾客可以清楚看见。NobHill的设计理念背后共有两个主题。首先,设计希望带出邻里的感觉,令顾客能在优雅而朴实的环境用餐和喝酒,并留下深刻印象。此外,第二个主题是带出秋意。NobHill的设计风格是尽量减少运用颜色和物料的变化。