Occurrence of Listeria and Enterobacteriaceae in domestic refrigerators

Consumers' refrigeration practices have a significant impact on the safety and quality of foods. To determine the prevalence and the identity of microorganisms in domestic refrigerators, swab samples were taken from various locations in the refrigerators from 137 households in middle Tennessee. The swabs were inoculated into different media, and standard procedures were used to characterize the isolates. API 20E and API Listeria were used for identification of Enterobacteriaceae and Listeria spp., respectively. The Kirby-Bauer technique was used to test resistance of the isolates. Actual counts for aerobic and Enterobacteriaceae ranged from not detected to 8.53 and 8.39 log CFU per sample, respectively. Klebsiella pneumoniae (23.4%), Klebsiella oxytoca (6.8%), Klebsiella terrigena (4.0%), Enterobacter sakazakii (2.2%), and Yersinia enterocolitica (0.7%) were some of the bacteria of concern that were isolated from domestic refrigerators. Resistance to antibiotics was most common in erythromycin (39.9%), followed by ampicillin (33.8%), cefoxitin (12.8%), tetracycline (5%), streptomycin (4.0%), nalidixic acid (2.1%), kanamycin (1.4%), and colistin (0.7%). None of the isolates tested was resistant to ciprofloxacin or gentamycin. Listeria spp. were also detected in six refrigerators. These findings underline the need for greater consumer education regarding proper refrigerator cleaning and safe food handling practices.     

Enantioselective epoxidations catalyzed by zeolite MCM-22 encapsulated Jacobsen's catalyst

A novel method for the encapsulation of homogeneous catalysts within the supercages (7.1×18.2 Å) of zeolite MCM-22 has been developed. By way of example, the well known asymmetric oxidation catalyst (R,R)-N,N-bis(3,5-di-tert-butylsalicylidedene)-1,2-cyclohexanediaminemanganese(III) chloride, a.k.a Jacobsen's catalyst, was occluded in MCM-22 during the zeolite synthesis. This ship-in-a-bottle complex exhibited both higher activity and enantioselectivity for the epoxidation of -methylstyrene compared with the homogeneous catalyst.     

Antibiotic susceptibility testing of Bifidobacterium thermophilum and Bifidobacterium pseudolongum strains: broth microdilution vs. agar disc diffusion assay

There is urgent need for having available suitable methods and data regarding the susceptibility levels of antibiotic resistant and sensitive strains of bifidobacteria. Based on a defined standard operation procedure, agar disc diffusion and broth microdilution were compared in order to evaluate the antimicrobial susceptibility profiles of 82 B. pseudolongum and 80 B. thermophilum strains mainly originating from the meat production chain. The methods that were assessed showed interpretable agreement within this study. The disc diffusion zone diameters are highly reproducible making the method a useful alternative to broth microdilution for antimicrobial susceptibility screening of bifidobacteria.     

Simulation of vacuum distillation to produce alcohol-free beer

Several processes have been developed for producing alcohol-free beer while maintaining desirable sensory characteristics. One of the most popular thermal processes used is distillation, where not only ethanol but volatile aromatic components are partly or completely removed from the beer. Based on data from the literature and using the Aspen Plus simulator, this study evaluates and compares the aroma profiles of alcohol-free beers obtained by continuous vacuum distillation with different pressures and processes. Three processes were simulated at pressures of 60, 102, and 200 mbar. The first (Process A) was a standard continuous vacuum distillation, where the bottom product was an alcohol-free beer. In the second (Process B), the bottom product was blended with a standard beer that had not undergone any thermal process. In the third (Process C), part of the top stream was mixed with the bottom product. This study considered eight major compounds in beer: ethanol, propanol, isobutanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl acetate, diacetyl and isoamyl acetate. The three simulated pressure ranges showed similar results, indicating that reducing the pressure below 200 mbar did not improve separation. Further, vacuum distillation did not remove diacetyl from the beer. Processes B and C resulted in beer that was richer in flavour compounds. Furthermore, when these processes were compared to Process A, the concentration of esters was markedly higher. © 2019 The Institute of Brewing & Distilling     

Study on the pilot-scale extraction of onion oleoresin using supercritical CO2

Supercritical carbon dioxide (SC-CO₂) was used to produce oleoresin from dried onion by pilot-scale extraction. The results showed that the extraction pressure and temperature affected the yield and sulphur concentration of onion oleoresin. Increase of the temperature from 45 to 65°C at 300 bar resulted in an increase of the yield and the sulphur concentration of oleoresin. At the same temperature (45°C) the yield was also higher at 300 bar than 100 bar while sulphur concentration of oleoresin got smaller at 300 bar than at 100 bar. The volatile composition of oleoresin displayed practically no differences as a function of extraction parameters. Comparison of different extraction methods showed that the yield after SC-CO₂ extraction was 22 times higher than that after steam distillation, but it was 14 or 39 times less than that after alcohol extraction, shaking at 25°C or in Soxhlet apparatus, respectively. The concentration of sulphur was the highest in steam distilled onion oil while it was the lowest in the extract of hexane and alcohol (at 25°C). The results of sensory evaluation showed that oleoresin extracted by SC-CO₂ was the first in ranking (at level of significance 0·05), before steam distilled oil and alcoholic extract. There was no significant difference between steam distilled oil and alcoholic extract in ranking, but the alcoholic extract was the least desirable, since the intensity of its off odour attribute was the highest. © 1998 SCI.     

Semantic networks for odors and colors in Alzheimer's disease.

Objective: Impairment in odor-naming ability and in verbal and visual semantic networks raised the hypothesis of a breakdown in the semantic network for odors in Alzheimer's disease (AD). The current study addressed this hypothesis. Method: Twenty-four individuals, half patients with probable AD and half control participants, performed triadic-similarity judgments for odors and colors, separately, which, utilizing the multidimensional scaling (MDS) technique of individual difference scaling analysis (INDSCAL), generated two-dimensional configurations of similarity. The abilities to match odors and colors with written name labels were assessed to investigate disease-related differences in ability to identify and conceptualize the stimuli. In addition, responses on attribute-sorting tasks, requiring the odor and color perceptions to be categorized as one polarity of a certain dimension, were obtained to allow for objective interpretation of the MDS spatial maps. Results: Whereas comparison subjects generated spatial maps based predominantly on relatively abstract characteristics, patients with AD classified odors on perceptual characteristics. The maps for patients with AD also showed disorganized groupings and loose associations between odors. Their normal configurations for colors imply that the patients were able to comprehend the task per se. The data for label matching and for attribute sorting provide further evidence for a disturbance in semantic odor memory in AD. The patients performed poorer than controls on both these odor tasks, implying that the ability to identify and/or conceptualize odors is impaired in AD. Conclusion: The results provide clear evidence for deterioration of the structure of semantic knowledge for odors in AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)