We characterize how different fracture size‐transmissivity relationships influence flow and transport simulations through sparse three‐dimensional discrete fracture networks. Although it is generally ...accepted that there is a positive correlation between a fracture's size and its transmissivity/aperture, the functional form of that relationship remains a matter of debate. Relationships that assume perfect correlation, semicorrelation, and noncorrelation between the two have been proposed. To study the impact that adopting one of these relationships has on transport properties, we generate multiple sparse fracture networks composed of circular fractures whose radii follow a truncated power law distribution. The distribution of transmissivities are selected so that the mean transmissivity of the fracture networks are the same and the distributions of aperture and transmissivity in models that include a stochastic term are also the same. We observe that adopting a correlation between a fracture size and its transmissivity leads to earlier breakthrough times and higher effective permeability when compared to networks where no correlation is used. While fracture network geometry plays the principal role in determining where transport occurs within the network, the relationship between size and transmissivity controls the flow speed. These observations indicate DFN modelers should be aware that breakthrough times and effective permeabilities can be strongly influenced by such a relationship in addition to fracture and network statistics.
Key Points
Breakthrough times and effective permeabilities in DFN simulations are influenced by the adopted relationship between size and aperture
Correlated relationship resulted in higher effective permeability values and earlier breakthrough times than networks without correlation
Fracture geometry controls where transport occurs in a DFN while the adopted relationship controls the speed of flow and transport times
Liquid smoke is a naturally derived flavor component and preservative with known antimicrobial properties. To our knowledge, there is a paucity of information on antifungal potential of liquid smoke ...against toxigenic fungi like
that produce mycotoxins in human and pet foods. Semi-moist pet food with high moisture content (20-30%) is susceptible to mold contamination and requires intervention. The objectives of this study were to determine the effects of liquid smoke preparations on the growth of wild-type mold and
in semi-moist pet food. Semi-moist pet food was formulated with eight different liquid smoke preparations (S1-S8) containing varying amounts of organic acids, phenol and carbonyl compounds (ranging from low to high) at 0% (untreated), 0.5, 1, 2, and 4% (w/w). A positive control consisted of 0.2% potassium sorbate known to inhibit mold growth. Shelf life was estimated by storing the samples at 28°C and 65-70% RH over 30 days and recording the number of days until the appearance of visible wild-type mold. In another experiment, samples were spot inoculated with
(∼10,000 CFU/mL), incubated at 25°C, and analyzed for fungal growth at sampling intervals of 2 days over a 35-day period. Liquid smoke at 0.5, 1, 2, and 4% extended the shelf life of samples on an average by a total of 11.6, 12.5, 17.2, and 24.1 days when compared to the untreated samples (7.7 days). The smoke preparations Cloud S-C100 (S3) and Code-10 (S6) (high carbonyl, medium/low phenol) were the most effective (
< 0.05) in prolonging the number of days to visible mold growth (26-28 days). In the challenge study with
, Cloud S-C100 (S3), Cloud S-AC15 (S8) (high to medium carbonyl, low phenol), and Code 10 (S6) (base smoke) reduced (
< 0.05) mold counts by 1.0, 1.7, and 2.5 logs when compared to the untreated samples at 1, 2, and 4%, respectively. Addition of smoke at 0.5% did not reduce mold counts. The carbonyl preparations of liquid smoke were the most effective at enhancing shelf life of semi-moist pet food, and at inhibiting
growth.
-contaminated pet foods could potentially become a source of human salmonellosis. This study evaluated the survival of
without and with the addition of acidulants in different fat types (chicken fat ...(CF), canola oil (CO), Menhaden fish oil (FO), lard (La), and tallow (Ta)) commonly used to coat dry pet food kibbles. The minimum inhibitory concentration (MIC) of individual acidulants and the combination were determined using the broth microdilution method. Autoclave-sterilized rendered fats were treated with pre-determined concentrations of antimicrobial acidulants (0.5% sodium bisulfate (SBS), 0.5% phosphoric acid (PA), 0.25% lactic acid (LA), etc.) and incubated overnight at 45 °C. The treated fats were inoculated with approximately eight logs of a
cocktail. Microbiological analyses were conducted separately for the fat-phase and water-phase at predetermined time intervals (0, 2, 6, 12, and 24 h) by plating them onto TSA plates. After incubating at 37 °C for 24 h, the plate count results were expressed as log CFU/mL. The MIC of SBS was 0.3125%, and of PA and LA were both 0.1953% against cocktail
serotypes. We observed a possible synergistic effect when SBS and organic acid were combined. All the acidulant tested at targeted concentrations individually as well as in combination with organic acids were highly effective against
spp. (non-detectable within 2 h) across different fat types. A potent anti-bactericidal effect leading to non-detectable
immediately (<1 h) at 45 °C was observed in the aqueous phase of the fish oil system, even without the addition of acidulants. These findings are significant for the dry pet food industries, where potential post-processing contamination of
could be controlled by treating fats and oils with acidulants.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Exposure to nerve agents, pyridostigmine bromide (PB), pesticides, and oil-well fires during the 1991 Gulf War (GW) are major contributors to the etiology of Gulf War Illness (GWI). Since the ...apolipoprotein E (APOE) ε4 allele is associated with the risk of cognitive decline with age, particularly in the presence of environmental exposures, and cognitive impairment is one of the most common symptoms experienced by veterans with GWI, we examined whether the ε4 allele was associated with GWI.
Using a case-control design, we obtained data on APOE genotypes, demographics, and self-reported GW exposures and symptoms that were deposited in the Boston Biorepository and Integrative Network (BBRAIN) for veterans diagnosed with GWI (n = 220) and healthy GW control veterans (n = 131). Diagnosis of GWI was performed using the Kansas and/or Center for Disease Control (CDC) criteria.
Age- and sex-adjusted analyses showed a significantly higher odds ratio for meeting the GWI case criteria in the presence of the ε4 allele (Odds ratio OR = 1.84, 95% confidence interval CI = 1.07-3.15, p ≤ 0.05) and with two copies of the ε4 allele (OR = 1.99, 95% CI 1.23-3.21, p ≤ 0.01). Combined exposure to pesticides and PB pills (OR = 4.10 2.12-7.91, p ≤ 0.05) as well as chemical alarms and PB pills (OR = 3.30 1.56-6.97 p ≤ 0.05) during the war were also associated with a higher odds ratio for meeting GWI case criteria. There was also an interaction between the ε4 allele and exposure to oil well fires (OR = 2.46, 95% CI 1.07-5.62, p ≤ 0.05) among those who met the GWI case criteria.
These findings suggest that the presence of the ε4 allele was associated with meeting the GWI case criteria. Gulf War veterans who reported exposure to oil well fires and have an ε4 allele were more likely to meet GWI case criteria. Long-term surveillance of veterans with GWI, particularly those with oil well fire exposure, is required to better assess the future risk of cognitive decline among this vulnerable population.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A technique for evaluating the (steady-state) creep stress exponent (n) from indentation data has come into common use over recent years. It involves monitoring the indenter displacement history ...under constant load and assuming that, once its velocity has stabilized, the system is in a quasi-steady state, with Stage II creep dominating the behaviour. The stress field under the indenter, and the way in which the creep strain field is changing there, are then represented by "equivalent stress" and "equivalent strain rate" values. These are manipulated in a similar manner to that conventionally employed with (uniaxial) creep test data, allowing the stress exponent, n, to be obtained as the gradient of a plot of the logarithm of the equivalent strain rate against the logarithm of the equivalent stress. The procedure is therefore a very simple one, often carried out over relatively short timescales (of the order of 1h or less). However, concerns have been expressed about its reliability, regarding the neglect of primary creep (after a very short initial transient) and about the validity of representing the stress and strain rate via these "equivalent" values. In this paper, comprehensive experimental data (both from a conventional, uniaxial loading set-up and from instrumented indentation over a range of conditions) are presented for two materials, focusing entirely on ambient temperature testing. This is supplemented by predictions from numerical (finite element method) modelling. It is shown that the methodology is fundamentally flawed, commonly giving unreliable (and often very high) values for n. The reasons for this are outlined in some detail. An attempt is made to identify measures that might improve the reliability of the procedure, although it is concluded that there is no simple analysis of this type that can be recommended.
Post-processing operations of extruded pet food kibbles involve coating the product with fats and flavorings. These processes increase the risk for cross-contamination with food-borne pathogens such ...as
and Shiga toxin-producing
(STEC)
and mycotoxin-producing molds such as
spp. after the thermal kill step. In this study, the antimicrobial effects of two types of organic acid mixtures containing 2-hydroxy-4-(methylthio) butanoic acid (HMTBa), Activate DA™ and Activate US WD-MAX™, against
STEC and
when used as a coating on pet food kibbles were evaluated. Using canola oil and dry dog digest as fat and flavor coatings, the efficacy of Activate DA (HMTBa + fumaric acid + benzoic acid) at 0%, 1% and 2%, and Activate US WD-MAX (HMTBa + lactic acid + phosphoric acid) at 0%, 0.5% and 1% was tested on kibbles inoculated with a cocktail of
serovars (Enteritidis, Heidelberg and Typhimurium) or Shiga toxin-producing
(STEC) serovars (O121, and O26) at 37 °C for 0, 12, 24, 48, 72 h, 30 and 60 days. Similarly, their efficacy was tested against
at 25 °C for 0, 3, 7, 14, 21, 28 and 35 days. Activate DA at 2% and Activate US WD-MAX at 1% reduced
counts by ~3 logs after 12 h and 4-4.6 logs after 24 h. Similarly, STEC counts were reduced by ~2 logs and 3 logs after 12 h and 24 h, respectively. Levels of
did not vary up to 7 days, and afterwards started to decline by >2 logs in 14 days, and up to 3.8-log reduction in 28 days for Activate DA and Activate US WD-MAX at 2% and 1%, respectively. The results suggest that the use of these organic acid mixtures containing HMTBa during kibble coating may mitigate post-processing enteric pathogen and mold contamination in pet food kibbles, with Activate US WD-MAX being effective at a lower concentration (0.5-1%) compared to Activate DA.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Raw meat-based diets (RMBDs) or sometimes described as biologically appropriate raw food (BARFs) are gaining in popularity amongst dog and cat owners. These pet guardians prefer their animals to eat ...minimally processed and more “natural” foods instead of highly heat-processed diets manufactured with synthetic preservatives. The market for RMBDs for dogs and cats is estimated at $33 million in the United States. This figure is likely underestimated because some pet owners feed their animals raw diets prepared at home. Despite their increasing demand, RMBDs have been plagued with numerous recalls because of contamination from foodborne pathogens like
Salmonella, E. coli
, or
Campylobacter
. Existing literature regarding mitigation strategies in RMBD's for dogs/cats are very limited. Thus, a comprehensive search for published research was conducted regarding technologies used in meat and poultry processing and raw materials tangential to this trade (e.g., meats and poultry). In this review paper, we explored multiple non-thermal processes and GRAS approved food additives that can be used as potential antimicrobials alone or in combinations to assert multiple stressors that impede microbial growth, ultimately leading to pathogen inactivation through hurdle technology. This review focuses on use of high-pressure pasteurization, organic acidulants, essential oils, and bacteriophages as possible approaches to commercially pasteurize RMBDs effectively at a relatively low cost. A summary of the different ways these technologies have been used in the past to control foodborne pathogens in meat and poultry related products and how they can be applied successfully to impede growth of enteric pathogens in commercially produced raw diets for companion animals is provided.
There has been increased interest among pet owners to feed vegetarian diets to their pets. However, the primary protein sources used in pet food today are animal based, warranting a need to evaluate ...novel plant-based ingredients to meet the protein demand. Corn fermented protein (CFP), a coproduct from ethanol production, may provide a plant-based alternative protein source for pet food. Therefore, the objectives of this study were to determine the effects of increasing levels of CFP on extrusion processing, stool quality, apparent total tract digestibility, and palatability in dog diets. Four extruded diets were fed to 12 adult beagle dogs in a replicated 4 × 4 Latin square design. The control diet contained 15% soybean meal (0C) and CFP was exchanged at either 5%, 10%, or 15% of soybean meal (5C, 10C, and 15C, respectively). Dogs were fed each dietary treatment for 9 days of adaption followed by 5 days of total fecal collection. Feces were scored on a 1–5 scale, with 1 representing liquid diarrhea and 5 representing hard pellet-like. Titanium dioxide (0.4%) was added to all diets as an external marker to estimate digestibility. Data were analyzed using orthogonal contrasts in SAS (version 9.4; SAS Institute, Inc., Cary, NC, USA). Dry bulk density of kibble decreased (
P
< 0.05), whereas kibble toughness increased (
P
< 0.05) with CFP inclusion. Fecal dry matter, dry fecal output, and defecations per day increased (
P
< 0.05) when dogs were fed increased levels of CFP. Dry matter and crude protein digestibility of CFP treatments were comparable (
P
> 0.05) to 0C. There was a decrease (
P
< 0.05) in organic matter, crude fat, gross energy, and total dietary fiber digestibility in the CFP treatments compared with 0C. A cubic relationship (
P
< 0.05) was observed in the digestibility of all nutrients except crude fat, indicating that 10C resulted in the lowest digestibility. For the palatability assessment, dogs had no preference when comparing the 5C treatment with the 0C treatment. Even with the differences in dietary treatments, inclusion of CFP at 5%, 10%, and 15% still resulted in acceptable processing parameters, kibble characteristics, and utilization when fed to dogs.
The storage mite Tyrophagus putrescentiae infests a wide range of food products including pet food. Control of this mite depends on chemical methods such as fumigation and spraying with insecticides. ...Methyl bromide was used as a fumigant for high-value stored products, especially to control mite infestation in dry-cured hams and cheeses, but it is now banned for most uses in many countries because of its atmospheric ozone-depleting effects. Effective alternatives to methyl bromide are needed to develop integrated pest management programs for this pest. Liquid smoke is a naturally derived flavoring and preservative with known antimicrobial properties. The objective of this study was to investigate the efficacy of liquid smoke preparations, with varying phenol and carbonyl concentrations and pH, on the survivability and orientation behavior of T. putrescentiae in a model semi-moist pet food. The mite survivability assays using liquid smoke-treated and untreated semi-moist pet food samples indicated that there was no difference among treatments (p > 0.05) for mite infestation and survival. Two-choice behavioral assays using semi-moist pet food cubes dipped in varying concentrations (0%, 0.3%, 1%, 5%, 10%, 25%, 50%, or 100% v/v) of liquid smoke preparations found that some of the liquid smoke preparations containing medium to high carbonyl content repelled the mites. In conclusion, liquid smoke did not kill or inhibit the mite population growth in semi-moist pet food. However, some liquid smoke fractions containing medium to high carbonyl content were repellent to mites and may retard mite infestation in stored semi-moist foods.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Contaminated surfaces can transmit pathogens to food in industrial and domestic food-handling environments. Exposure to pathogens on food contact surfaces may take place via the cross-contamination ...of pathogens during postprocessing activities. Formaldehyde-based commercial sanitizers in recent years are less commonly being used within food manufacturing facilities due to consumer perception and labeling concerns. There is interest in investigating clean-label, food-safe components for use on food contact surfaces to mitigate contamination from pathogenic bacteria, including
. In this study, the antimicrobial effects of two types of organic acid mixtures containing 2-hydroxy-4-(methylthio) butanoic acid (HMTBa), Activate DA™ and Activate US WD-MAX™, against
when applied onto various food contact surfaces were evaluated. The efficacy of Activate DA (HMTBa + fumaric acid + benzoic acid) at 1% and 2% and Activate US WD-MAX (HMTBa + lactic acid + phosphoric acid) at 0.5% and 1% against
(serovars Enteritidis, Heidelberg, and Typhimurium) were evaluated on six different material surfaces: plastic (bucket elevator and tote bag), rubber (bucket elevator belt and automobile tire), stainless steel, and concrete. There was a significant difference in the
log reduction on the material surfaces due to the organic acid treatments when compared to the untreated surfaces. The type of material surface also had an effect on the log reductions obtained. Stainless steel and plastic (tote) had the highest
log reductions (3-3.5 logs), while plastic (bucket elevator) and rubber (tire) had the lowest log reductions (1-1.7 logs) after treatment with Activate US WD-MAX. For Activate DA, the lowest log reductions (~1.6 logs) were observed for plastic (bucket elevator) and rubber (tire), and the highest reductions were observed for plastic (tote), stainless steel, and concrete (2.8-3.2 logs). Overall, the results suggested that Activate DA at 2% and Activate US WD-MAX at 1% are potentially effective at reducing
counts on food contact surfaces by 1.6-3.5 logs.
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