Matrices, Fish/Cooked Seafood, Meat/Frozen Cooked Meat Products, Nuts and Nut Products/Tree Nut Meats. Approved By, AOAC. Method Number, recommended by AOAC Official Method (1). The ap- propriate dilutions were analyzed by the AOAC pour plate method (AOAC ) and the SimPlate . AOAC Compendium of Methods for the Microbiological Examination of Foods 4th Edition: Chapter 7. FDA Bacteriological Analytical Manual: Chapter 3.
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A precollaborative study was conducted to compare a pectin gel ColiChrome 2 Redigel plating method to the MPN fermentation tube method, Five separate lots of each product were tested and each lot was represented by low, medium and high total coliform and E. Therefore, various media formulations can be easily made according to the standard accepted ingredients for each individual medium.
Following the introduction of the technology by RCR Scientific, the idea was copied by most of the major media makers worldwide since the RCR patent only covered the U. This oyster tissue activity apparently interferes with the obvious expression of red coliform CFUs. In-house studies with fresh clams and mussels have indicated that this activity is either lacking in their tissues or is at such low levels as to not interfere with excellent recovery of total coliforms with ColiChrome 2 Redigel.
Therefore, 15 samples of each 9966.23 the 20 products were tested by each method. The mean comparisons for each method and level indicated no significant differences among any of the aoav except for the MPN and VRB Redigel at the low level for coliforms. Results for coliforms can be obtained in 24 h. The mean comparisons for each method and level indicated no significant differences among any of the methods except for the MPN and Petrifilm EC at the high level of coliforms.
However, there was no significant difference among all the other methods for both coliforms and E. Also, it should be noted that the results for the oysters werein general, excellent for the E. Totally accurate differentiation of woac coliforms and E.
Precollab Study – Micrology Labs
Bontrager of RCR Scientific. Each test was done with the three tube MPN procedure and with duplicate plates in each of the other methods.
The mean comparisons for each method and level indicated no significant differences among any of the methods except for Petrifilm EC with ColiChrome 2 Redigel and VRB Redigel at the low levels for coliforms. The decision to base this study on a comparison of ColiChrome 2 Redigel to the standard MPN method was influenced by the fact that other recent collaborative studies have been done and approved on the basis of this format 5,6.
Following are some observations and comments for Duncan’s Multiple Range Test for coliforms. The results of samples of 20 foods were collected and statistically analyzed. Micrology Laboratories currently serves the food and dairy industry with its line of Easygel and Coliscan media. The complete set of data for all samples is given in Table 5. 96.23 MPN and ColiChrome 2 Redigel differed significantly in two other instances, aac being in the corn at the low level and the pasteurized milk at the high level of bacteria.
However, we believe that the direct comparisons of the four methods contribute significantly to questions about the methods. Dairy – Seafoods – Meats – Vegetables cheddar cheese fish frozen beef raw ground broccoli frozen cottage cheese oysters fresh meat pot pie frozen corn frozen milk pasteurized shrimp fresh turkey raw ground mushrooms fresh milk raw yogurt.
However, there was no significant difference between the MPN and other methods for coliforms. The precollaborative study therefore has lain dormant since then until the reacquisition of the ColiChrome technology by RCR Scientific who sold it to Micrology Laboratories Also, thanks to F.
The procedures were followed according to instructions provided with the product and the counts were made in accordance with the protocol established in the collaborative study of the product 6. The mean comparisons for each method and level indicated no significant differences aoad the medium level, but significant differences at the high levels of coliforms for all methods compared to the MPN and at the low levels of coliforms for Petrifilm EC and VRB Redigel.
Both red and purple blue colonies were counted at both 24 h and 48 h. Likewise, the Duncan mean comparisons for E. The Duncan mean comparisons for E. Brief comments on each of the food products follows. The mean comparisons for each method and level indicated no significant differences among any of the methods except for MPN and ColiChrome 2 Redigel at low levels of coliforms and E.
For the ColiChrome 2 Redigel method, of samples of 20 foods, This study resulted in considerably more insights and information than originally expected. VRB Redigel plates aoc incubated at 35 C for 48 h and colonies were counted at 24 and 966.3 h. Further confirmation of the E. It should be noted that the names ColiChrome 2 Redigel and Coliscan Easygel are synonymous for the same original product, so that whatever pertains to ColiChrome 2 Redigel is equally true for Coliscan Easygel.
Total coliforms produce the enzyme galactosidase which cleaves the first substrate to form an insoluble red dye. Based upon the results of this study, we believe that any of the three rapid methods may be used effectively to differentiate and confirm coliforms or E. The mean comparisons for each method and level indicated no significant differences among any of the methods and levels except for MPN with all the others at the low levels for coliforms.
Petrifilm plates were incubated at 35 C for 48 h and colonies were counted at 24 and 48 h.