Compact Dry Research Articles

Evaluation of a Compact Dry Method for Enumerating Bacteria in Contaminated Foods

Evaluation of a Compact Dry Method for Enumerating Bacteria in Contaminated Foods

Isolamento de Escherichia coli e Staphylococcus aureus em leite cru de tanques de refrigeração: identificação e perfis de resistência antimicrobiana

Escherichia coli and Staphylococcus aureus in milk cooling tank reflects a hygienic deficit in animal management, production environment, and milk obtainment. With implications for public health as agents of infection and food poisoning, and the presence of antimicrobial-resistant strains. Therefore, were investigated in cooling tanks with high counts of somatic cells and total bacteria in milk. Microorganisms, in which a profile of resistance to antimicrobials was investigated, and whether there was a similarity in this profile between the strains of the eight dairy properties.Therefore, eighty-eight samples were obtained, and inoculated on Compact Dry® plates. Of this total, 27.27% (24/88) samples tested positive for E. coli and 56.81% (50/88) for S. aureus. Among 24 E. coli strains subjected to disk-diffusion antibiograms, 70.83% were resistant to rifampicin, 50% to ampicillin and 41.67% to cefoxitin and erythromycin, while of the 51 S. aureus strains, 94.32% expressed resistance to azetroanam, 86.27% to ampicillin and nalidixic acid, 76.47% to rifampicin and 47.06 % to erythromycin and cefoxitin. A criterion of resistance to over three antibiotics was observed for 8.33% (2/24) of the isolated E. coli strains and 17.65% (9/51) of the S. aureus strains, characterizing them as multidrug resistant (MDR) strains. Resistance phenotypes displayed high similarity between properties F5 and F6 for S. aureus, and properties F6 and F8 for E. coli when applying the Jaccard index. The presence of these antibiotic-resistant pathogenic microorganisms indicate flaws in milk production handling and sanitary conditions, representing risk to milk consumers.

Defect-free drying of large fine-particle zirconia compacts prepared by gelcasting method

In this work, drying of bodies prepared by gelcasting fine submicrometre-sized zirconia particles was studied and a drying process for defect-free bodies with large cross-sections was proposed. It was found that the cracking of large bodies could be prevented by reducing the monomer content and using appropriate non-volatile cosolvents. Glycerol and polyethylene glycols with different molecular weights were used as non-volatile cosolvents in aqueous ceramic suspensions. The complex effects of the individual cosolvents on the gelcasting process and, in particular, on the drying step were investigated and explained. The applicability of individual cosolvents for the gelcasting process were discussed and their optimal use was indicated.

Evaluation of the InTray and Compact Dry culture systems for the diagnosis of urinary tract infections in patients presenting to primary health clinics in Harare, Zimbabwe

Antimicrobial resistance surveillance data is lacking from many resource-limited settings mainly due to limited laboratory testing. Novel culture systems may address some of the limitations of conventional culture media and expand the availability of microbiology services. The aims of this study were to evaluate the performance of InTray COLOREX Screen/ESBL and Compact Dry for the detection of uropathogens and of extended-spectrum beta-lactamase (ESBL)-producing organisms from urine samples. Urines samples were collected from patients presenting with symptoms of urinary tract infection to primary care clinics in Harare. Performance of the InTray COLOREX Screen, ESBL and Compact Dry chromogenic media were compared to the reference of culture using Brilliance UTI agar and conventional antimicrobial susceptibility testing. A total of 414 samples were included in the analysis. Of the included samples, 98 were positive on Brilliance UTI agar and 83 grew Enterobacterales. The sensitivities and specificities for Enterobacterales were 89.2% (95% CI 80.4–94.9) and 98.2% (95% CI 96.1–99.3) for InTray Screen and 95.2% (95% CI 88.1–98.7) and 99.7% (95% CI 98.3–100) for Compact Dry. Extended-spectrum beta-lactamases were present in 22 isolates from the Brilliance UTI agar. The sensitivity of the InTray COLOREX ESBL culture plates for the detection of ESBL-producing organisms was 95.5% (95% CI 77.2–99.9) and specificity was 99.5% (95% CI 98.2–99.9%). Our findings show good performance of the novel culture systems for the detection of uropathogens and ESBL-producing organisms. Both systems have several advantages over conventional media and have the potential to expand and decentralize laboratory testing.

Electrophoretic deposition of coatings and bulk compacts using magnesium-doped aluminum oxide nanopowders

The electrophoretic deposition (EPD) of coatings and bulk compacts in a wide range of thicknesses (from 23 to 1800 μm) from stable suspensions of a magnesium-doped aluminum oxide nanopowder with subsequent sintering of samples into dense ceramics was studied. The initial nanopowder was obtained by the method of electric explosion of an Al-Mg alloy wire with a Mg content of 1.3 wt. %. The study of the dispersion composition, kinetics of deaggregation under the ultrasonic treatment and zeta potential in the nanopowder-based suspensions was carried out. It was shown that a nearly linear increase in the deposited mass and thickness of EPD deposits occurred at a constant voltage of 20 V and an average deposition current of approximately 40 μA when the deposition time was varied from 1 to 180 min. Drying of the coatings with a thickness of less than 35 μm led to the formation of a net of small cracks, while drying of the bulk compacts with a thickness of more than 1 mm occurred without cracking. The ceramic bulk sample with a thickness of 1.2 mm and the density of 98.7% TD was successfully obtained by sintering at 1650 °C for 4 h. It was characterized by a dense grain structure with an average grain size of 5 μm and the presence of a small number of closed pores less than 1 μm in size. Sintering of ceramics was revealed to be accompanied by the formation of a MgAl2O4 crystalline spinel phase, localized mainly at grain boundaries.

Presencia de microorganismos micóticos en leche cruda de tanques de enfriamiento en el Altiplano Boyacense (Colombia)

Las levaduras y los mohos son gérmenes que no se deben encontrar en muestras de leche porque son potencialmente patógenos tanto para los animales como para el ser humano. Debido a su alta manipulación durante la recolección, almacenamiento y transporte, la leche es susceptible de contaminación con estos microorganismos, por lo cual su detección en este alimento en estas fases, es relevante con el fin de prevenir posibles situaciones que comprometan la salud pública. El objetivo del presente trabajo fue determinar la presencia de mohos y levaduras en muestras de tanques de enfriamiento de leche en el Altiplano Boyacense. Se tomaron muestras de 20 tanques de enfriamiento de leche cruda ubicados en 20 diferentes municipios lecheros del departamento de Boyacá con el fin de determinar la presencia de mohos y levaduras a través de Compact Dry YM®. El 35% de las muestras de leche no presentó crecimiento de mohos ni de levaduras, por su parte, en el 25% se encontró crecimiento de colonias de color amarillo y sus tonalidades, lo que correspondería con colonias de mohos, en el 5% se determinó el crecimiento únicamente de colonias azules, correspondiente a crecimiento de levaduras. En el 35% restante se detalló un crecimiento de colonias azules y amarillas. Esto demuestra que existe un alto porcentaje mohos y levaduras en muestras de leche cruda refrigerada, situación que podría desencadenar un problema de salud pública.

Citizen science-based water quality monitoring: Constructing a large database to characterize the impacts of combined sewer overflow in New York City.

To protect recreational water users from waterborne pathogen exposure, it is crucial that waterways are monitored for the presence of harmful bacteria. In NYC, a citizen science campaign is monitoring waterways impacted by inputs of storm water and untreated sewage during periods of rainfall. However, the spatial and temporal scales over which the monitoring program can sample are constrained by cost and time, thus hindering the construction of databases that benefit both scientists and citizens. In this study, we first illustrate the scientific value of a citizen scientist monitoring campaign by using the data collected through the campaign to characterize the seasonal variability of sampled bacterial concentration as well as its response to antecedent rainfall. Second, we examine the efficacy of the HyServe Compact Dry ETC method, a lower cost and time-efficient alternative to the EPA-approved IDEXX Enterolert method for fecal indicator monitoring, through a paired sample comparison of IDEXX and HyServe (total of 424 paired samples). The HyServe and IDEXX methods return the same result for over 80% of the samples with regard to whether a water sample is above or below the EPA's recreational water quality criteria for a single sample of 110 enterococci per 100mL. The HyServe method classified as unsafe 90% of the 119 water samples that were classified as having unsafe enterococci concentrations by the more established IDEXX method. This study seeks to encourage other scientists to engage with citizen scientist communities and to also pursue the development of cost- and time-efficient methodologies to sample environmental variables that are not easily collected or analyzed in an automated manner.

Matrix Extension Study: Validation of Compact Dry YM for Enumeration of Yeast and Mold in Selected Foods.

Nissui Compact Dry YM was originally certified by the AOAC Research Institute Performance Tested Methods SM (PTM) program (PTM No. 100401) for enumeration of yeasts and molds in fruit products after 7 days of incubation. A matrix extension study, organized by Campden BRI (Chipping Campden, United Kingdom), was conducted to extend the method's claim to cooked deli turkey, fresh whole tomatoes, cheese (Wensleydale), sliced white bread, and mayonnaise. In addition, the method was evaluated at 3 and 7 days to validate the 3 day incubation period. Compact Dry YM is a ready-to-use dry media sheet, containing a cold-soluble gelling agent, selective agents, and chromogenic medium, which are rehydrated by adding 1 mL diluted sample. Yeasts and molds appear as blue colonies, while molds can also have a cottony appearance and the color may vary. Users can obtain total yeast and mold count following 3-7 days of incubation at 25 ± 1°C. Method comparison data for cooked deli turkey, fresh whole tomatoes, cheese (Wensleydale), sliced white bread, and mayonnaise were collected in a single-laboratory evaluation by Campden BRI. A multilaboratory study was conducted on orange juice with 10 laboratories participating including the organizing laboratory. Compact Dry YM was compared to ISO 21527-1:2008, Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of yeasts and molds - Part 1: Colony count technique in products with water activity greater than 0.95, the current standard at the time of this study. Each matrix was evaluated for total yeasts and molds at each contamination level (including an uncontaminated level). In the single-laboratory evaluation (cooked deli turkey, fresh whole tomatoes, cheese, sliced white bread, and mayonnaise), colony counts were logarithmically transformed, and then the data were analyzed at each level for repeatability (sr), RSD of repeatability (RSDr), and mean difference between methods with a 95% confidence interval (CI). A CI outside a range of (-0.5 to 0.5) on the log10 mean difference between methods was used as the criterion to establish a significant statistical difference. In the multilaboratory study on orange juice, after logarithmic transformation the data were analyzed for sr, RSDr, and mean difference with 95% CIs and also for reproducibility (sR) and RSD of reproducibility (RSDR). Regression analysis was performed on all matrixes and reported as r2. Results from Compact Dry YM at 3 and 7 days were compared separately to ISO 21527-1 and then to each other. In the single-laboratory evaluation, five contamination levels were tested. With the exception of cheese, there were few, if any, colonies recovered at the two lowest contamination levels. As a consequence, differences of a few colonies resulted in significant statistical differences indicated between Compact Dry YM (at both 3 and 7 days) and ISO 21527-1 for most of the foods at these levels. At the three higher contamination levels, statistical differences were seen between Compact Dry YM at 3 days and the ISO method for cooked deli turkey at the middle level, tomatoes at the two middle levels, sliced white bread at the two highest levels, and mayonnaise at the middle level. After 7 days, statistical differences remained between Compact Dry and ISO methods, based on the CIs, but mean differences between methods were <0.5 log10 CFU/g for all foods at the three highest contamination levels. When comparing results between Compact Dry YM at 3 and 7 days, statistical differences were indicated for tomatoes and sliced white bread, both in the second highest contamination level. Otherwise, differences between results at 3 and 7 days were small. The sr and RSDr values were similar for Compact Dry YM (both days) and ISO 21527-1, and r2 values were ≥0.84 for all comparisons. In the multilaboratory study for orange juice, there were no statistical differences between methods across 11 data sets. Four contamination levels were tested, and at all levels mean differences between methods were <0.1 log10 CFU/mL, and CIs were smaller than (-0.05, 0.15), well within the acceptance criterion of (-0.5, 0.5). The sr, RSDr, sR, and RSDr were similar for each method, and r2 was 1.0 in all comparisons. Results indicate that Compact Dry YM offers comparable results at 3 days to the ISO standard plating method at 5 days, in a space-saving, easy-to-use format.

Matrix Extension Study: Validation of the Compact Dry CF Method for Enumeration of Total Coliform Bacteria in Selected Foods.

The Compact Dry "Nissui" CF method, Performance Tested Method(SM) 110401, was originally certified for enumeration of coliform bacteria by the AOAC Research Institute Performance Tested Methods(SM) program for raw meat products. Compact Dry CF is a ready-to-use dry media sheet, containing a cold-soluble gelling agent, a chromogenic medium, and selective agents, which are rehydrated by adding 1 mL of diluted sample. Coliform bacteria produce blue/blue-green colonies on the Compact Dry CF, allowing a coliform colony count to be determined in the sample after 24 ± 2 h incubation. A validation study was organized by Campden BRI (formerly Campden and Chorleywood Food Research Association Technology, Ltd), Chipping Campden, United Kingdom, to extend the method's claim to include cooked chicken, fresh bagged prewashed shredded iceberg lettuce, frozen fish, milk powder, and pasteurized 2% milk. Campden BRI collected single-laboratory data for cooked chicken, lettuce, frozen fish, and milk powder, whereas a multilaboratory study was conducted on pasteurized milk. Thirteen laboratories participated in the interlaboratory study. The Compact Dry CF method was compared to ISO 4832:2006 "Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of coliforms-Colony-count technique," the current version at the time this study was conducted. Each matrix was evaluated at either four or five contamination levels of coliform bacteria (including an uncontaminated level). After logarithmic transformation of counts at each level, the data for pasteurized whole milk were analyzed for sr, sR, RSDr, and RSDR. Regression analysis was also performed and r(2) was reported. Mean difference between methods with 95% confidence interval (CI) was calculated. A log10 range of -0.5 to 0.5 for the CI was used as the acceptance criterion to establish significant statistical difference between methods. In the single-laboratory evaluation (for cooked chicken, lettuce, frozen fish, and milk powder), sr and RSDr values were analyzed and r(2) was reported. Statistical differences were indicated between the Compact Dry CF and ISO 4832 methods in two of five contamination levels tested for lettuce, and in the low contamination levels for cooked chicken, frozen fish, and dry milk powder. For the low levels of cooked chicken, frozen fish, and milk powder, only a few colonies were recovered for each method, and thus not a true indication of the methods' performance. In most cases, mean differences between the Compact Dry CF and ISO 4832 methods were small (<0.5 log10), with CIs within the acceptance criterion. The sr and RSDr values were similar for both methods, and r(2) values were >0.94 for all matrixes. In the multilaboratory study, no statistical differences were indicated between methods. The sr, RSDr, sR, and RSDr values were similar for each method and even slightly smaller for the Compact Dry CF. The r(2) value was 0.99. The Compact Dry CF method offers comparable results to ISO 4832 in a space saving, easy-to-use format.

Matrix Extension Study: Validation of the Compact Dry TC Method for Enumeration of Total Aerobic Bacteria in Selected Foods.

A validation study was conducted to extend the matrix claim for the Nissui Compact Dry Total Count (TC), Performance Tested Method(s)(SM) (PTM) Certification No. 010404, to cooked chicken, lettuce, frozen fish, milk powder, and pasteurized whole milk. The method was originally certified by the AOAC Research Institute Performance Tested Method(s)(SM) Program for raw meat products. The Compact Dry TC is a ready-to-use dry media sheet that is rehydrated by adding 1 mL of diluted sample. A total aerobic colony count can be determined in the sample following 48 h of incubation. Matrix extension studies were conducted by Campden BRI (formerly Campden and Chorleywood Food Research Association Technology Limited), Chipping Campden, UK. Single-laboratory data were collected for cooked chicken, lettuce, frozen fish, and milk powder, whereas a multilaboratory study was conducted on pasteurized milk. Fourteen laboratories participated in the collaborative study. The Compact Dry TC was tested at two time points, 48 ± 3 h and 72 ± 3 h and compared with the current International Organization for Standardization (ISO) method at the time of the study, ISO 4833:2003 (this standard is withdrawn and has been replaced by: ISO 4833-1:2013 and ISO 4833-2:2013), Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of microorganisms-Colony-count technique at 30°C. The data were logarithmically transformed and evaluated for repeatability (plus reproducibility for pasteurized milk), RSD of repeatability (plus RSD of reproducibility for milk), r(2), and mean difference between methods with 95% confidence interval (CI). A CI outside of (-0.5 to 0.5) on the log10 mean difference was used as the criterion to establish significant statistical difference between methods. No significant differences were found between the Compact Dry TC 48 and 72 h time points, with the exception of one contamination level of cooked chicken and one contamination level of dry milk powder. Mean differences were small at these levels (<0.5 log10), but the upper CIs were above 0.5. Statistical differences were indicated between the Compact Dry TC and ISO 4833 in two of five contamination levels tested each for lettuce and frozen fish. In each case, mean differences were >0.5 log10, and the total aerobic colony count was higher for the ISO method. In most cases, mean differences between the Compact Dry and ISO methods were small (<0.5 log10) with CIs within the acceptance criterion. Repeatability, reproducibility, and RSD were similar for both methods, and r(2) values were >0.97 for all matrixes. The Compact Dry TC, at 48 h, offers the advantage of a shorter time to results than ISO 4833 in an easy-to-use format.

Matrix Extension Study: Validation of the Compact Dry EC Method for Enumeration of Escherichia coli and non-E. coli Coliform Bacteria in Selected Foods.

The Compact Dry "Nissui" EC method, originally certified by the AOAC Research Institute Performance Test Method(SM) program for enumeration of Escherichia coli and non-E. coli coliforms in raw meat products (Performance Tested Method(SM) 110402), has undergone an evaluation to extend the method's claim to cooked chicken, prewashed bagged shredded iceberg lettuce, frozen cod filets, instant nonfat dry milk powder, and pasteurized milk (2% fat). Compact Dry EC is a ready-to-use dry media sheet containing a cold-soluble gelling agent, selective agents, and a chromogenic medium, which are rehydrated by adding 1 mL diluted sample. E. coli form blue/blue-purple colonies, whereas other coliform bacteria form red/pink colonies. Users can obtain an E. coli count (blue/blue-purple colonies only) and a total coliform count (red/pink plus blue/blue-purple colonies) after 24 ± 2 h of incubation at 37 ± 1°C. The matrix extension study was organized by Campden BRI (formerly Campden and Chorleywood Food Research Association Technology, Ltd), Chipping Campden, United Kingdom. Method comparison data for cooked chicken, prewashed bagged shredded iceberg lettuce, frozen cod filets, and instant nonfat dry milk powder were collected in a single-laboratory evaluation by Campden BRI. A multilaboratory study was conducted on pasteurized milk (2% fat), with 13 laboratories participating. The Compact Dry EC method was compared to ISO 16649-2:2001 "Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of beta-glucuronidase-positive Escherichia coli-Part 2: Colony-count technique at 44 degrees C using 5-bromo-4-chloro-3-indolyl beta-D-glucuronide" and to ISO 4832:2006 "Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of coliforms-Colony-count technique," the current standards at the time of this study. Each matrix was evaluated separately for E. coli and non-E. coli coliforms at each contamination level (including an uncontaminated level). In the single-laboratory evaluation (cooked chicken, prewashed bagged shredded iceberg lettuce, frozen cod filets, and instant nonfat dry milk powder), colony counts were logarithmically transformed, and then the data were analyzed at each level for sr, RSDr, and mean difference between methods with 95% confidence intervals (CIs). A CI outside a range of -0.5 to 0.5 on the log10 mean difference between methods was used as the criterion to establish a significant statistical difference. In the multilaboratory study on pasteurized milk, after logarithmic transformation, the data were analyzed for sR and RSDR in addition to sr, RSDr, and mean difference with 95% CIs. Regression analysis was performed on all matrixes and reported as r(2). In the single-laboratory evaluation, statistical differences were indicated between the Compact Dry EC and ISO 16649-2 methods for the enumeration of E. coli in two of five contamination levels tested for lettuce, and in the low contamination level for cooked chicken. For the cooked chicken and lettuce at the low level, only a few colonies were recovered for each method, and thus not a true indication of the methods' performance. For the high contamination level of lettuce, counts varied within the sets of five replicates more than 10-fold for each method, which may have contributed to the significant difference. Statistical differences were also indicated between the Compact Dry EC and ISO 4832 methods for the enumeration of coliforms in two of five contamination levels tested for lettuce, two of five contamination levels of milk powder, and in the low contamination level for frozen fish. For the lowest levels of frozen fish and milk powder, only a few colonies were recovered for each method. For the lettuce and the other level of milk powder, counts varied within the sets of five replicates more than 10-fold for each method, which may have contributed to the significant differences indicated in the those contamination levels. In most cases, mean differences between the Compact Dry EC and International Organization of Standardization (ISO) methods were well below 0.5 log10, and the CIs were within the acceptance criterion (-0.5 to 0.5). The sr and RSDr values were similar for both methods, and r(2) values were >0.92 for all comparisons. In the multilaboratory study, no statistical differences were indicated between the methods. The sr, RSDr, sR, and RSDr values were similar for each method and even slightly smaller in most cases for the Compact Dry EC. The r(2) value was 0.97 in comparison to ISO 16649-2, and 0.99 in comparison to ISO 4832. The Compact Dry EC offers comparable results to the ISO standard plating methods in a space saving, easy-to-use format.

Influence of phenylalanine dispersant on colloidal processing of alumina particles

This paper reports the adsorption behavior of phenylalanine (PHA) onto alumina surfaces in a wide pH range of 3.6–9.5, rheology and packing densities of concentrated alumina suspensions with PHA, and mechanical properties of consolidated alumina compacts with and without PHA. A small amount of PHA was adsorbed on both the positively and negatively charged alumina surfaces and enhanced zeta potential of alumina particles in acidic and basic suspensions. However, the adsorbed and free PHA provided little influence on the dispersibility of primary particles. In the neutral and basic suspensions, the apparent viscosity decreased with addition of PHA because of the formation of weakly coagulated particle clusters, leading to the increase in the packing density for neutral alumina suspensions. During drying of wet alumina compacts, PHA remaining in the alumina compacts relaxed the applied compressive stress. However, added PHA provided no influence on Young׳s moduli and compressive strengths of alumina compacts after calcination.

A Numerical Assessment of the Air Flow Behaviour in a Conventional Compact Dry Kiln

Convective drying is the most common drying strategy used in timber manufacturing industries in the developing world. In convective drying, the reduction rate of the moisture content is directly affected by the flow topology in the inlet and exit plenums and the air flow velocity in the channels formed by timber layers. Turbulence, boundary layer separation, vortex formation and recirculation regions are flow features that are intrinsically associated with the kiln geometry, which in turn dictate the flow velocity across the timber stack and, ultimately, the drying rate. Within this framework, this work presents a numerical study of the effects of the plenum width and inlet flow velocity in a compact dry kiln aiming to establish design recommendations to ensure the highest possible level of flow uniformity across the lumber stack. The numerical solution of the mathematical model is obtained through the finite-volume based Ansys CFX R flow solver. Validation of the numerical approximation is performed by comparing numerical and experimental flow velocities for a scale model of a kiln available in the literature.

Evaluation of a novel dry sheet culture method (Sanita-kunR) for rapid enumeration of yeasts and molds in foods

Sanita-kunR Yeasts and Molds (SkYM), a novel dry sheet culture method for rapid enumeration of fungi, has been developed. This re-hydrated plate consists of a unique adhesive sheet, non-woven fabric coated with nutrients, antibiotic, water absorption polymer and uniquely synthesized 2-(2-methoxyphenyl)-3-(4-nitrophenyl)-5-phenyl-tetrazolium chloride for rapid enumeration of yeasts and molds. When SkYM was assessed using 37 microbes including 33 fungal strains, 29 fungal strains (87.9%) were formed red colored colonies within 48h whereas all yeasts and molds tested formed colonies within 72h. All tested bacteria failed to grow. The SkYM method, with both 48 and 72h of incubation, was compared with Dichloran Rose-Bengal Chloramphenicol Agar (DRBC; 5days) according to ISO 21527-1, and with 3M Petrifilm YM (PYM; 5days) and Nissui Compact Dry YM (CDYM; 5days) commercially available dry culture methods using 100 naturally contaminated foods. The linear correlation coefficients of SkYM (48h) with DRBC, PYM and CDYM were 0.921, 0.929 and 0.947, respectively, whereas the linear correlation coefficients between SkYM (72h) and DRBC, SkYM (72h) and PYM, SkYM (72h) and CDYM were 0.948, 0.877 and 0.911, respectively. These results demonstrated that SkYM was a useful alternative for rapid enumeration of yeasts and molds in foods.

Evaluation of the Dry Sheet Medium (Compact Dry ETBR) for Enumerating Enterobacteriaceae in Meat Samples

Compact Dry ETB(R) (CD-ETB, ETB; Enterobacteriaceae) , a ready-to-use and self-diffusible dry medium sheet culture system for the detection and enumeration of Enterobacteriaceae, was evaluated. A total of 35 Enterobacteriaceae strains, which were studied for the inclusivity study, grew and formed red-purple colored colonies on the CD-ETB(R). When 17 gram-negative bacteria other than Enterobacteriaceae were inoculated for the exclusivity study, 2 strains grew and formed red-purple colonies, 9 strains formed colorless colonies, and 6 strains failed to grow. A total of 43 gram-positive bacteria and 3 yeasts failed to grow. The CD-ETB method was compared with the Violet Red Bile Glucose (VRBG) agar method according to ISO 21528-2 and the 3M Petrifilm(TM) EB (3M-EB(R)) method in 53 meat samples. The correlation coefficients between CD-ETB(R) and VRBG agar, CD-ETB(R) and 3M-EB(R), and 3M-EB(R) and VRBG agar were 0.962, 0.992 and 0.960, respectively.

Evaluation of the dry sheet medium (Compact Dry LS) for screening of total Listeria count in food samples

The Compact Dry LS (CD-LS), ready-to-use dry sheet selective medium for Listeria species, was evaluated for inclusivity and exclusivity by using 107 strains including 20 Listeria species strains. All tested Listeria species strains other than Listeria seeligeri that grew as blue colored colony on CD-LS. CD-LS were compared with those on Oxford agar and ALOA agar as conventional methods using Listeria species inoculated from 100 food samples. The correlation coefficients between CD-LS and Oxford agar, and CD-LS and ALOA agar were 0.983 and 0.978, respectively. Our results suggested CDLS was a suitable alternative medium for screening of Listeria species.

The compaction properties of sodium chloride in the presence of moisture

Abstract The effect of moisture on the behaviour of sodium chloride under compression was investigated by measurement of compaction forces and ejection forces. Saturated solution present at the crystal surfaces effected a reduction in friction at the inter-particulate boundary and between the particles and the die wall. Dry material formed compacts of higher strength than wet material except at low pressures. Subsequent drying of compacts prepared in the presence of moisture resulted in an increase in strength due to interparticulate recrystallisation.

Evaluation of the Compact Dry X-SA Method for Enumerating Staphylococcus aureus in Artificially Contaminated Food Samples

Compact Dry X-SA (CD-XSA), a ready-to-use and self-diffusible dry medium sheet culture system for the detection and enumeration of Staphylococcus aureus, was evaluated. A total of 50 S. aureus strains, which were studied for the inclusivity study, grew as blue-colored colonies on the CD-XSA. When 114 bacteria other than S. aureus and 3 yeasts were inoculated for the exclusivity study, 37 strains produced white colonies, and 4 strains produced blue colonies, and 3 strains produced magenta colonies, while 73 other strains failed to grow. The CD-XSA method was compared with the mannitol salt agar with egg yolk (MSEY) method, the Baird-Parker agar (BP) method and the 3M Petrifilm(TM) STX (3M-STX) method in 105 artificially contaminated food samples. The correlation coefficients between CD-XSA and MSEY, CD-XSA and BP, and CD-XSA and 3M-STX were 0.945, 0.960 and 0.977, respectively.

Evaluation of the Compact Dry VP Method for Screening Raw Seafood for Total Vibrio parahaemolyticus

Compact Dry VP (CDVP) is a ready-to-use method for enumerating Vibrio parahaemolyticus in food. The presterilized plates contain a culture medium comprising peptone, NaCl, bile salts, antibiotics, chromogenic substrates, and polysaccharide gum as a cold water–soluble gelling. After diluting raw seafood samples in a phosphate-buffered saline solution, a 1-ml aliquot was inoculated onto the center of the plate and allowed to diffuse by capillary action. Blue-green colonies forming on the plates were counted after 18 to 20 h of incubation at 35°C. A total of 85 V. parahaemolyticus strains (62 tdh+ strains and 23 tdh− strains) were studied for inclusivity, 81 (95.3 %) of which produced blue-green colonies. When 97 strains (14 strains of Vibrio spp., 33 strains of coliform bacteria, and 50 strains of noncoliform bacteria) were assessed for exclusivity, 10 strains of Vibrio spp. produced non–blue-green colonies, and 87 strains failed to grow. The CDVP and U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA-BAM) methods were compared with the use of four different types of raw seafood that were inoculated with four different V. parahaemolyticus strains. For raw tuna and oysters, the FDA-BAM colony lift method was used, whereas the FDA-BAM most-probable-number method was used for salmon and scallop. The linear correlation coefficients between the CDVP and FDA-BAM methods were 0.99 for fresh raw tuna, 0.95 for fresh raw oysters, 0.95 for frozen raw salmon, and 0.95 for frozen raw scallops. These results suggest that the CDVP method is useful for screening raw seafood for V. parahaemolyticus.

Comparison of Dry Sheet Media and Conventional Agar Media Methods for Enumerating Yeasts and Molds in Food

A study was done to compare Nissui Compact Dry Yeast and Mold plates (CDYM), 3M Petrifilm Yeast and Mold count plates (PYM), dichloran–rose bengal chloramphenicol (DRBC) agar, and dichloran 18% glycerol (DG18) agar for enumerating yeasts and molds naturally occurring in 97 foods (grains, legumes, raw fruits and vegetables, nuts, dairy products, meats, and miscellaneous processed foods and dry mixes). Correlation coefficients for plates incubated for 5 days were DG18 versus DRBC (0.93), PYM versus DRBC (0.81), CDYM versus DG18 (0.81), PYM versus DG18 (0.80), CDYM versus DRBC (0.79), and CDYM versus PYM (0.75). The number of yeasts and molds recovered from a group of foods (n = 32) analyzed on a weight basis (CFU per gram) was not significantly different (α= 0.05) when samples were plated on DRBC, DG18, PYM, or CDYM. However, the order of recovery from foods (n = 65) in a group analyzed on a unit or piece basis, or a composite of both groups (n = 97), was DRBC > DG18 = CDYM > PYM. Compared with PYM, CDYM recovered equivalent, significantly higher (α= 0.05) or significantly lower (α= 0.05) numbers of yeasts and molds in 51.5, 27.8, and 20.6%, respectively, of the 97 foods tested; respective values were 68.8, 15.6, and 15.6% in the small group (n = 32) and 43.1, 33.8, and 23.1% in the large group (n = 65) of foods. The two groups contained different types of foods, the latter consisting largely (73.8%) of raw fruits (n = 16) and vegetables (n = 32). Differences in efficacy of the four methods in recovering yeasts and molds from foods in the two groups are attributed in part to differences in genera and predominant mycoflora. While DG18 agar, CDYM, and PYM appear to be acceptable for enumerating yeasts and molds in the foods analyzed in this study, overall, DRBC agar recovered higher numbers from the 97 test foods, thereby supporting its recommended use as a general purpose medium for mycological analysis.