33 research outputs found
Computer Simulation of Energy Use Greenhouse Gas Emissions and Costs for Alternative Methods of Processing Fluid Milk
Pilot-scale crossflow-microfiltration and pasteurization to remove spores of Bacillus anthracis (Sterne) from milk
High-temperature, short-time pasteurization of milk
is ineffective against spore-forming bacteria such as
Bacillus anthracis (BA), but is lethal to its vegetative
cells. Crossflow microfiltration (MF) using ceramic
membranes with a pore size of 1.4 μm has been shown
to reject most microorganisms from skim milk; and,
in combination with pasteurization, has been shown to
extend its shelf life. The objectives of this study were
to evaluate MF for its efficiency in removing spores
of the attenuated Sterne strain of BA from milk; to
evaluate the combined efficiency of MF using a 0.8-μm
ceramic membrane, followed by pasteurization (72°C,
18.6 s); and to monitor any residual BA in the permeates
when stored at temperatures of 4, 10, and 25°C
for up to 28 d. In each trial, 95 L of raw skim milk
was inoculated with about 6.5 log10 BA spores/mL of
milk. It was then microfiltered in total recycle mode
at 50°C using ceramic membranes with pore sizes of
either 0.8 μm or 1.4 μm, at crossflow velocity of 6.2 m/s
and transmembrane pressure of 127.6 kPa, conditions
selected to exploit the selectivity of the membrane.
Microfiltration using the 0.8-μm membrane removed
5.91 ± 0.05 log10 BA spores/mL of milk and the 1.4-
μm membrane removed 4.50 ± 0.35 log10 BA spores/
mL of milk. The 0.8-μm membrane showed efficient
removal of the native microflora and both membranes
showed near complete transmission of the casein proteins.
Spore germination was evident in the permeates
obtained at 10, 30, and 120 min of MF time (0.8-μm
membrane) but when stored at 4 or 10°C, spore levels
were decreased to below detection levels (≤0.3 log10
spores/mL) by d 7 or 3 of storage, respectively. Permeates
stored at 25°C showed coagulation and were
not evaluated further. Pasteurization of the permeate
samples immediately after MF resulted in additional
spore germination that was related to the length of
MF time. Pasteurized permeates obtained at 10 min of
MF and stored at 4 or 10°C showed no growth of BA
by d 7 and 3, respectively. Pasteurization of permeates
obtained at 30 and 120 min of MF resulted in spore
germination of up to 2.42 log10 BA spores/mL. Spore
levels decreased over the length of the storage period
at 4 or 10°C for the samples obtained at 30 min of MF
but not for the samples obtained at 120 min of MF.
This study confirms that MF using a 0.8-μm membrane
before high-temperature, short-time pasteurization
may improve the safety and quality of the fluid milk
supply; however, the duration of MF should be limited
to prevent spore germination following pasteurization
Functional properties of sodium and calcium caseinate antimicrobial active films containing carvacrol
Active edible films were prepared by adding carvacrol into sodium caseinate (SC) and calcium caseinate (CC) matrices plasticized with two different glycerol concentrations (25 and 35 wt%) prepared by solvent casting. Functional characterisation of these bio-films was carried out by determination of some of their physico-chemical properties, such as colour, transparency, oxygen barrier, wettability, dye permeation properties and antibacterial effectiveness against Gram negative and Gram positive bacteria. All films exhibited good performance in terms of optical properties in the CIELab space showing high transparency. Carvacrol was able to reduce CC oxygen permeability and slightly increased the surface hydrophobicity. Dye diffusion experiments were performed to evaluate permeation properties. The diffusion of dye through films revealed that SC was more permeable than CC. The agar diffusion method was used for the evaluation of the films antimicrobial effectiveness against Escherichia cell and Staphylococcus aureus. Both SC and CC edible films with carvacrol showed inhibitory effects on both bacteria. (C) 2013 Elsevier Ltd. All rights reserved.This research was supported by the Ministry of Science and Innovation of Spain through the projects MAT2011-28468-C02-01, MAT2011-28468-C02-02 and HP2008-0080. M.P. Arrieta thanks Fundacion MAPFRE for "Ignacio Hernando de Larramendi 2009-Medio Ambiente" fellowship (MAPFRE-IHL-01). Authors thank Ferrer Alimentacion S.A., for providing the caseinates powders.Arrieta, MP.; Peltzer, MA.; López Martínez, J.; Garrigós Selva, MDC.; Valente, AJM.; Jimenez Migallon, A. (2014). Functional properties of sodium and calcium caseinate antimicrobial active films containing carvacrol. Journal of Food Engineering. 121:94-101. https://doi.org/10.1016/j.jfoodeng.2013.08.015S9410112
Curriculum-based measurement of oral reading (R-CBM): A diagnostic test accuracy meta-analysis of evidence supporting use in universal screening
A great deal of research over the past decade has examined the appropriateness of curriculum-based measurement of oral reading (R-CBM) in universal screening. Multiple researchers have meta-analyzed available correlational evidence, yielding support for the interpretation of R-CBM as an indicator of general reading proficiency. In contrast, researchers have yet to synthesize diagnostic accuracy evidence, which pertains to the defensibility of the use of R-CBM for screening purposes. The overall purpose of this research was to therefore conduct the first meta-analysis of R-CBM diagnostic accuracy research. A systematic search of the literature resulted in the identification of 34 studies, including 20 peer-reviewed articles, 7 dissertations, and 7 technical reports. Bivariate hierarchical linear models yielded generalized estimates of diagnostic accuracy statistics, which predominantly exceeded standards for acceptable universal screener performance. For instance, when predicting criterion outcomes within a school year (≤ 9 months), R-CBM sensitivity ranged between .80 and .83 and specificity ranged between .71 and .73. Multiple moderators of R-CBM diagnostic accuracy were identified, including the (a) R-CBM cut score used to define risk, (b) lag in time between R-CBM and criterion test administration, and (c) percentile rank corresponding to the criterion test cut score through which students were identified as either truly at risk or not at risk. Follow-up analyses revealed substantial variability of extracted cut scores within grade and time of year (i.e., fall, winter, and spring). This result called into question the inflexible application of a single cut score across contexts and suggested the potential necessity of local cut scores. Implications for practices, directions for future research, and limitations are discussed