EFFECT OF STORAGE TEMPERATURE ON THE GROWTH OF LISTERIA MONOCYTOGENES ON QUESO BLANCO SLICES*

A five‐strain cocktail of Listeria monocytogenes (10⁴ cfu/mL) was inoculated onto individual vacuum‐packaged slices (ca. 50 g each) of a commercial, Hispanic‐style cheese, that being Queso Blanco. Growth was determined at appropriate intervals during storage at 5, 10, 15, 20 and 25C. In general, as the incubation temperature increased, a shorter lag phase duration (LPD) and a faster growth rate (GR) were observed. The LPD values at 5, 10, 15, 20 and 25C were 65.3, 19.9, 2.1, 8.4 and 11.4 h, respectively. The GR values were 0.011, 0.036, 0.061, 0.090 and 0.099 log cfu/h at 5, 10, 15, 20 and 25C, respectively. There were no statistical differences in LPD at 10, 15, 20 and 25C. However, the LPD during growth at 5C was statistically (P ≤ 0.05) longer than at all other temperatures. The GR values at 20 and 25C were not significantly different from each other, whereas the GR values at 5, 10 and 15C were significantly different from each other as well as from the GR at 20 and 25C (P ≤ 0.05). The maximum population density (MPD) showed relatively little variation over the range of storage temperatures tested, with an average of 8.38 log cfu/g (SD = 0.33). The results of this study indicate that not even the lowest trial temperature of 5C prevented growth over time of the inoculated L. monocytogenes on this sliced product, and that proper storage and handling procedures are required to prevent the bacterium from contaminating the product and/or to control its growth.     

EFFECT OF POSTRIGOR SARCOMERE LENGTH ON MECHANICAL AND STRUCTURAL CHARACTERISTICS OF RAW AND HEAT-DENATURED SINGLE PORCINE MUSCLE FIBRES

Light microscopy during tensile tests was used to examine the effect of postrigor sarcomere length (SL) on mechanical and structural characteristics of raw and heat-denatured (1 h at 80C) muscle fibres of porcine longissimus lumborum and the structural deformation mechanisms of such fibres inducing mechanical differences. The effect of the collagenous network associated with single coldshortened muscle fibres on maximum stress was analysed. Muscle bundles developed rigor at 2C (cold-shortened = CS), at22C (control = C), and at 22C     

RELATIONSHIP BETWEEN REPRESSION-SENSITIZATION AND PHYSICAL ILLNESS.

HYPOTHESIZED THAT BOTH SENSITIZERS AND REPRESSERS EXCEED THOSE INDIVIDUALS FALLING IN THE MIDDLE OF THE DISTRIBUTION WITH RESPECT TO FREQUENCY AND SEVERITY OF ILLNESSES. EXP. I UTILIZED 2 INDEPENDENT SAMPLES OF UNDERGRADUATES (N = 173 AND 319) WHO WERE GIVEN THE REPRESSION-SENSITIZATION (R-S) SCALE AND A HEALTH SURVEY. THERE WAS NO SUPPORT FOR THE CURVILINEARITY HYPOTHESIS, BUT ON 12 HEALTH ITEMS IN BOTH SAMPLES, SENSITIZERS INDICATED GREATER FREQUENCY AND/OR SEVERITY OF ILLNESS THAN DID REPRESSERS. IN THE EXP. II A SUBSAMPLE OF 85 EXTREME SCORERS ON THE R-S SCALE FROM A POOL OF 319 SS WERE COMPARED WITH RESPECT TO THE NUMBER OF VISITS MADE TO THE UNIVERSITY HEALTH CENTER DURING 1 ACADEMIC YR. ANALYSIS OF VARIANCE INDICATED THAT MALE SENSITIZERS DO IN FACT SEEK MEDICAL HELP SIGNIFICANTLY MORE FREQUENTLY THAN MALE REPRESSERS; FOR FEMALES, HEALTH CENTER VISITS WERE UNRELATED TO R-S SCORES. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of LiF on Hot-Pressing of MgO

Transparent polycrystalline specimens can be fabricated from fine MgO powder with a small LiF addition by a two-step process: hot-pressing and heat-treating. The LiF addition allows MgO to be hot-pressed to near theoretical density at reduced temperatures and stresses. The stress-temperature-time conditions must be designed to attain a hot-pressed density of at least 99.5% of the theoretical density of MgO to obtain a transparent specimen during the subsequent heat treatment used in this study. Possible densification mechanisms are discussed.     

THE DISRUPTION COSTS OF POST–9–11 SECURITY MEASURES AND CITIES’ BIDS FOR PRESIDENTIAL NOMINATING CONVENTIONS

Over the past several decades, cities have increasingly built facilities and amenities to attract tourism, conventions, and mega‐events. Mega‐events bring cities tourism revenues and free media attention to brand themselves. We theorize regarding why cities seek to host presidential nominating conventions and why the increased disruption costs of the post–9–11 security environment have changed the way cities evaluate the branding opportunities of mega‐events. Consistent with our predictions, larger and more tourism‐dependent cities are less likely to need the branding opportunities of political conventions than their competitors and therefore are less willing to incur the disruption costs of political conventions after 9–11.     

A review of potassium nutrition in grapevines with special emphasis on berry accumulation

Potassium (K) is essential for vine growth and yield. Grape berries are a strong sink for K, particularly during ripening. Excess K levels in grape berries may have a negative impact on wine quality, mainly because it decreases free tartaric acid resulting in an increase in the pH of grape juice, must and wine. In Australia, high K status is common in most vineyards, which reflects the high K and high pH values of most Australian grape juice. This necessitates pH adjustment during the vinification process, and tartaric acid addition is a common practice in most Australian wineries. High K concentration may also lead to excessive loss of the additional tartaric acid by precipitation as potassium bitartrate and, as a consequence, pH adjustment becomes more difficult and expensive. Ensuring naturally low K levels in the berry will help reduce costs of input and waste management at the winery. Potential vineyard management options to manipulate berry K accumulation include selective use of rootstock/scion combination, canopy management and irrigation strategies. However, the impact of these practices on determining the optimum K concentration requires careful calibration of production parameters and the desirable grape juice and wine quality in relation to tissue K concentration. This paper reviews and discusses the possible functions of K in grape berries, translocation of K into the berry, and genetic and cultural factors that may affect the accumulation of K in the berry. This will help to identify the key research and management strategies needed for controlling K concentrations in grape berries.