Compact Dry Research Articles

Comparison of the Compact Dry EC with the Most Probable Number Method (AOAC Official Method 966.24) for Enumeration of Escherichia coli and Coliform Bacteria in Raw Meats: Performance-Tested MethodSM 110402

Compact Dry E. coli/Coliform Count (EC) is a ready-to-use test method for the enumeration of Escherichia coli and coliform bacteria in food. The plates are presterilized and contain culture medium and a cold water-soluble gelling agent. The medium should be rehydrated with 1 mL diluted sample inoculated onto the center of the self-diffusible medium, allowing the solution to diffuse by capillary action. The plate can be incubated at 35 degrees C for 20-24 h and the colonies counted without any further working steps. The Compact Dry EC medium plates were validated as an analysis tool for determining colony-forming units (CFU) of E. coli and coliform bacteria from a variety of raw meats using 5 different types of raw meats. The performance tests were conducted at 35 degrees C. In all studies performed, no apparent differences were observed between the Compact Dry EC method and the AOAC Official Method 966.24 results. For the accuracy claim (n = 75), a correlation factor of r2 = 0.93 (E. coli) and r2 = 0.93 (coliform bacteria) could be assigned, as stated in the application for "Performance-Tested Method."

Comparison of the compact dry YM with the FDA BAM method for enumeration of yeasts and molds in fruit-based products. Performance-Tested Method 100401.

Compact Dry YM is a ready-to-use test method for the enumeration of yeasts and molds in fruit-based products. The plates are presterilized and contain nonwoven incorporated nutrients supplemented with antibiotics and a chromogenic enzyme substrate, 5-bromo-4-chloro-3-indoxyl phosphate, p-toluidine salt (X-phos), to facilitate counting dyes, and a cold water-soluble gelling agent. The medium should be rehydrated with 1 mL of diluted sample inoculated onto the center of the self-diffusible medium, allowing the solution to diffuse immediately by capillary action. The plate can be incubated at 25 degrees C for 7 days. The Compact Dry YM medium plates were validated as an analysis tool determining colony forming units of yeasts and molds from a variety of fruit-based products using 5 different fruit products. The performance tests were conducted at 25 degrees C. In all studies performed, no apparent differences were observed between the Compact Dry YM method and the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA BAM) method results (P > 0.05). For the accuracy claim (n = 75), a correlation factor of r2 = 0.99 could be assigned, as stated in the application for Performance-Tested Method.

Comparison of the Compact Dry CF with the Most Probable Number Method (AOAC Official Method 966.24) for Enumeration of Coliform Bacteria in Raw Meats: Performance-Tested MethodSM 110401

Compact Dry CF is a ready-to-use test method for the enumeration of coliform bacteria in food. The plates are presterilized and contain culture medium and a cold water-soluble gelling agent. The medium should be rehydrated with 1 mL diluted sample inoculated into the center of the self-diffusible medium, allowing the solution to diffuse by capillary action. The plate can be incubated at 35 degrees C for 20-24 h and the colonies counted without any further working steps. The Compact Dry CF medium plates were validated with 5 different raw meats. The performance tests were conducted at 35 degrees C. In all studies performed, no apparent differences were observed between the Compact Dry CF method and the AOAC Official Method 966.24 results. For the accuracy claim (n = 75), a correlation factor of r2 = 0.91 (coliform) could be assigned, as stated in the application for Performance-Tested Method. No significant variations in coliform bacterial counts were observed with different production lots or plates of diverse storage age by the quality consistency and storage robustness studies.

Comparison of the Compact Dry TC Method with the Standard Pour Plate Method (AOAC Official Method 966.23) for Determining Aerobic Colony Counts in Food Samples: Performance-Tested MethodSM

Compact Dry TC qualifies as a rapid method kit for determining aerobic colony counts in foods. The plates are presterilized and contain culture medium and a cold-soluble gelling agent. The medium is rehydrated by inoculating 1 mL diluted sample into the center of the self-diffusible medium and allowing the solution to diffuse by capillary action. The plates can then be incubated and the colonies counted without any additional steps. The Compact Dry TC method was validated with 5 different raw meats. The performance tests were conducted at 35 degrees and 30 degrees C. In all required performance studies, no apparent differences were observed between the Compact Dry TC method and the Standard Pour Plate method (AOAC Official Method 966.23) for the detection level of aerobic microorganisms. For the accuracy claim (n = 60), a correlation factor of r2(35) = 0.9977 (35 degrees C) and r2(30) = 0.9932 (30 degrees C) could be assigned, as stated in the application for "Performance Tested Method." Quality consistency and storage robustness studies, showed no significant variations in plate count results with different production lots or plates of diverse storage age.

Microwave Assisted Processing of Ceramics

Microwave heating can provide cost and time effective processing routes for ceramic systems. Microwave heating assisted drying of green compacts, low temperature sintering of certain oxides, and partial or complete nitridization, carburization or reduction of hemi-oxides have been attempted recently. Using a multi-mode microwave cavity, we were able to reduce MeOx (where Me = Cu and Ag) to their sub-oxides or base metal at close to room temperature within minutes. The product sub-oxides or metals were identified and characterized for their crystallinity and phase purity. The results suggest that the microwave heating can provide an alternative, cost effective route for alloying for certain metals. The criteria for effectiveness of microwave heating and the coupling between the materials and the electromagnetic wave are discussed.

Comparison of the Compact Dry TC and 3M Petrifilm ACP Dry Sheet Media Methods with the Spiral Plate Method for the Examination of Randomly Selected Foods for Obtaining Aerobic Colony Counts

Two hundred thirty-six randomly selected food and milk samples were examined to obtain aerobic colony counts by two dry sheet media methods and a standard Public Health Laboratory Service spiral plate method. Results for 40 samples were outside the limits of detection for one or more of the tested methods and were not considered. (The limits of detection for the spiral plate method were 200 to 1 × 108 CFU/ml for the spiral plate method and 100 to 3 × 106 CFU/ml for the dry sheet media methods.) The remaining 196 sets of results were analyzed further. When the results from the three methods were compared, correlation coefficients were all >0.80 and slopes and intercepts were close to 1.0 and 0.0, respectively. Mean log values and standard deviations were very similar for all three methods. The results were evaluated according to published UK guidelines for ready-to-eat foods sampled at the point of sale, which include a quality acceptability assessment that is based on aerobic colony counts. Eighty-six percent of the comparable results gave the same verdict with regard to acceptability according to the aerobic colony count guidelines. Both dry sheet media methods were comparable to the spiral plate method and can be recommended for the examination of food.

Synthesis of Whisker Reinforced Mullite Matrix Composites Using Colloidal Processing

CVD-processed ultrafine mullite powder (<0.1μm)-micrometer size Si3N4-whisker or mullite-whisker were dispersed in H2O-C2H5OH-C3H8O3 with a low surface tension at pH 4.0 to prevent cracking during drying of wet green compacts consolidated by filtration. The rheological behavior of suspensions, consolidation process of the solids by filtration, and the pore structures of green compacts were studied to understand the formation of crack-free dense powder compacts with uniformly dispersed whiskers in the nanometer size matrix mullite. The crack-free powder compacts were hot-pressed at 1500°C for 1h at 10 to 39MPa in N2 atmosphere or pressureless-sintered at 1600° to 1650°C for 4 or 10h in air or vacuum. The monolithic mullite (99.9% T.D.) and 10% mullite-whisker-added mullite (91.2% T.D.) with the average strengths of 468MPa and 242MPa, respectively, showed little degradation of strength at 1300°C. The composite with 10vol% Si3N4-whisker (99.8% T.D.) showed a high average strength (632MPa) at room temperature, while the strength decreased to 341MPa at 1300°C. The fracture toughness (1.68MPa⋅m0.5) of the monolithic mullite was increased to 2.94MPa⋅m0.5 by the addition of 10% Si3N4-whisker.

Colloidal Processing and Mechanical Properties of Whisker‐Reinforced Mullite Matrix Composites

Aqueous colloidal suspensions in the two systems of CVD‐processed ultrafine mullite powder (&lt;0.1 μm), ‐Si3N4 whisker and ‐mullite whisker, were prepared near the isoelectric point of mullite (pH 7.0) to prevent cracking during drying of wet green compacts consolidated by filtration. The freeze‐dried porous green compacts were hot‐pressed with a carbon die at 1500°C for 1 h at a pressure of 39 MPa in N2 atmosphere. The relative densities of the mullite matrix composites with whiskers of 0 to 10 vol% were in the range of 95.2% to 99.8%. Increasing the fraction of Si3N4 whisker increased the density, flexural strength, and fracture toughness of the hot‐pressed composites. On the other hand, addition of the mullite whisker increased the fracture toughness but decreased the density and strength of the composites.

Drying of Silicon Powder Compacts

Laser-synthesized silicon powder with an average size of 0.28 {mu}m was colloidally pressed into disks 1.27 cm in diameter using various solvents. Thermogravimetric analysis (TGA) was performed during the solvent removal at various temperatures. Two types of weight loss were observed: one proportional to time, t, indicating that external mass transfer is the rate-limiting step, and the other proportional to t{sup 1/2}, indicating that pore diffusion is the rate-determining step. After losing > 99% of the solvent weight, samples were examined by Fourier transform ir spectroscopy to determine the amount of solvent that remained adsorbed on the surface of the silicon powder as a function of time for various temperatures. Temperatures much higher than the boiling points of the solvents are required to completely dry the silicon compacts.

Drying and sintering of Al2O3 compacts made by sol—gel processing

Drying and sintering of Al2O3 compacts made by sol—gel processing