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61.
Yolanda Moreno M. Carmen Collado M. Antonia Ferrús José M. Cobo Enrique Hernández & Manuel Hernández 《International Journal of Food Science & Technology》2006,41(3):275-280
The viability of lactic acid bacteria (LAB) from commercial fermented milks was studied during storage at 4 °C. The enumeration of total viable bacteria was assessed using fluorescence microscopy. Plate counting on selective media was used to enumerate LAB. Using LIVE/DEAD® BacLightTM viability staining, it was observed that bacterial counts decreased gradually after expiry dates, the number of viable bacteria remaining above 106 bacteria g?1 for all of the products. Viable cell counts estimated by plating onto selective media were lower than those obtained by direct microscopic counting. The viability of LAB contained in acid products decreased during their storage period at 4 °C. All products contain viable LAB ranging from 108 to 109 bacteria g?1 and could be considered as probiotic, given that the recommended minimum number of probiotic bacteria in such food products is approximately 107 bacteria mL?1 product. The number of bifidobacteria in commercial fermented milks declared to contain bifidobacteria varied from 104 to 107 bacteria mL?1. This study confirms the usefulness of fluorescent techniques for a rapid and accurate evaluation of bacterial viability in probiotic products. 相似文献
62.
63.
Watts Alan G.; Kelly Andrea B.; Sanchez-Watts Graciela 《Canadian Metallurgical Quarterly》1995,109(6):1146
The authors have demonstrated in rats that the ingestion of hypertonic saline for 5 days provides an increasingly complex dehydrating stimulus to the rats. Initially, the stimulus leads to cellular dehydration, but extracellular dehydration develops as ingestion continues beyond 3 days. The initial cellular dehydration provokes modifications to corticotropin-releasing hormone and neurotensin/neuromedin N messenger RNAs (mRNAs) in some neurons of the limbic forebrain, changes that are either maintained or are modified as extracellular dehydration develops. These changes in mRNA content occur in neurosecretory neurons as well as in neurons in hypothalamic and telencephalic regions associated with behavior and autonomic regulation. The authors propose that alterations in peptide mRNAs are allied to altered neuronal signaling processes that direct the different components of the homeostatic response to dehydration. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
64.
Diñeiro Y Menéndez MI Blanco-López MC Lobo-Castañón MJ Miranda-Ordieres AJ Tuñón-Blanco P 《Analytical chemistry》2005,77(20):6741-6746
A methodology based on density functional theory calculations for the design of molecularly imprinted polymers (MIPs) is described. The method allows the rational choice of the most suitable monomer and polymerization solvent among a set of chemicals traditionally used in MIP formulations for the molecular imprinting of a given template. It is based on the comparison of the stabilization energies of the prepolymerization adducts between the template and different functional monomers. The effect of the polymerization solvent is included using the polarizable continuum model. A voltammetric sensor for homovanillic acid was constructed using different MIPs as recognition element, confirming that the solvent (toluene) and functional monomer (methacrylic acid) selected according to the theoretical predictions lead to the most efficient molecular recognition sensing phase. With the voltammetric sensor prepared using the MIP designed according to the theoretical predictions, a linear response for concentrations of homovanillic acid between 5 x 10(-8) and 1 x 10(-5) M can be obtained. The limit of detection is 7 x 10(-9) M. The selectivity obtained for homovanillic acid over other structurally related compounds buttresses the validity of this strategy of design. 相似文献
65.
Direct chemical sensing in liquid environments using polymer-guided shear horizontal surface acoustic wave sensor platforms on 36 degrees rotated Y-cut LiTaO3 is investigated. Design considerations for optimizing these devices for liquid-phase detection are systematically explored. Two different sensor geometries are experimentally and theoretically analyzed. Dual delay line devices are used with a reference line coated with poly (methyl methacrylate) (PMMA) and a sensing line coated with a chemically sensitive polymer, which acts as both a guiding layer and a sensing layer or with a PMMA waveguide and a chemically sensitive polymer. Results show the three-layer model provides higher sensitivity than the four-layer model. Contributions from mass loading and coating viscoelasticity changes to the sensor response are evaluated, taking into account the added mass, swelling, and plasticization. Chemically sensitive polymers are investigated in the detection of low concentrations (1-60 ppm) of toluene, ethylbenzene, and xylenes in water. A low-ppb level detection limit is estimated from the present experimental measurements. Sensor properties are investigated by varying the sensor geometries, coating thickness combinations, coating properties, and curing temperature for operation in liquid environments. Partition coefficients for polymer-aqueous analyte pairs are used to explain the observed trend in sensitivity for the polymers PMMA, poly(isobutylene), poly(epichlorohydrin), and poly(ethyl acrylate) used in this work. 相似文献
66.
Eduardo Cassel Rubem Mário Figueiró Vargas Gerti Weber Brun Diego Erthal Almeida Laura Cogoi Graciela Ferraro Rosana Filip 《Journal of food engineering》2010
In this work a study about extracts obtained from Ilex paraguariensis St. Hil. leaves with supercritical CO2 was carried out. Experiments were performed in a pilot-scale extractor with capacity of 1 L at pressure of 120, 150, 170 and 200 bar for four temperature conditions, 313.15, 323.15, 333.15 and 343.15 K. The experimental data were fitted using a mathematical model characterized by the existence of two distinct periods of extraction. Numerical results for the adjusted parameters correlated very well the supercritical extraction experimental data. The confidence of results obtained from mathematical model and experiments was assured through the chi-square test. 相似文献
67.
Madrera Roberto Rodríguez Valles Belén Suárez García Yolanda Diñeiro del Valle Argüelles Paula Lobo Anna Picinelli 《Food science and biotechnology》2010,19(4):1129-1134
Work has commenced on the study and characterization of wood native species (oak, chestnut, cherry, alder, ash, and beech),
employed to a minor extent in enology, for their application in the elaboration of distillates. To this end, furanic and low
molecular weight phenol compounds, total phenolic content, and antioxidant activity in alcoholic extracts by maceration of
wood chips at 2 toasting levels were studied. Significant differences between samples, technologically relevant, were due
both to species and toasting time. Furthermore, extracts showed interesting antioxidant activities equivalent in some cases
to than those reported for alcoholic beverages aged in wood. 相似文献
68.
69.
Adhesion properties and competitive pathogen exclusion ability of bifidobacteria with acquired acid resistance 总被引:1,自引:0,他引:1
The adhesion properties of Bifidobacterium longum and Bifidobacterium catenulatum strains with an acquired resistance to acid and their ability to competitively exclude Salmonella enterica serovar Typhimurium, Escherichia coli, Listeria monocytogenes, Enterobacter sakazakii, and Clostridium difficile from adhering to human intestinal mucus were evaluated and compared with the results when the same experiments were run with the original acid-sensitive strains. In half of the four studied cases, the acid-resistant derivative showed a greater ability to adhere to human intestinal mucus than the original strain. The ability of bifidobacteria to inhibit pathogen adhesion to mucus was not generally improved by the acquisition of acid resistance. In contrast, three of the four acid-resistant strains showed a greater ability to displace preadhered pathogens than the original strains, especially preadhered Salmonella Typhimurium and C. difficile. Overall, the induction of acid resistance in bifidobacteria could be a strategy when selecting strains with enhanced stability and improved surface properties that favor their potential functionality as probiotics against specific pathogens. 相似文献
70.
Carla Luciana Gerez Maria Ines Torino Graciela Rollán Graciela Font de Valdez 《Food Control》2009,20(2):144-148
The ability of lactic acid bacteria (LAB) to inhibit Aspergillus, Fusarium, and Penicillium, the main contaminants in bread, was evaluated. Only four strains (Lactobacillus plantarum CRL 778, Lactobacillus reuteri CRL 1100, and Lactobacillus brevis CRL 772 and CRL 796) from 95 strains tested displayed antifungal activity. The major antifungal compounds were acetic and phenyllactic acids. The fermentation quotient (FQ = 2.0) and the leaven volume (80 cm3) of doughs with LB and yeasts were higher than doughs without LB. The inclusion of antifungal LAB strains in the starter culture allowed a reduction in the concentration of calcium propionate by 50% while still attaining a shelf life similar to that of traditional bread containing 0.4% CP. 相似文献