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bioMérieux saTEMPO® TVC (Total Viable Count) TestCat. No.: 80007PTM Status: December 27, 2006Certificate No.: 120602

Summary of Validation Claims

The TEMPO® TVC (Total Viable Count) method is an automated system for the enumeration of total aerobic

mesophilic flora in foods. The method uses a selective dehydrated culture medium and an enumeration card con-taining 48 wells across three different dilutions for the automatic determination of the most probable number (MPN).

The TEMPO® TVC test was validated and certified as a Performance-Tested MethodSM (PTM) by the AOAC Research Institute (RI) as an effective method

for the enumeration of total aerobic bacteria in a variety of foods, includ-ing raw ground pork, raw ground beef, cooked roast beef, smoked turkey, fresh ground chicken, frozen cooked chicken nuggets, cooked chicken, heat-processed grilled chicken, frozen catfish, heat-processed frozen fish, heat-processed crab cakes, raw cod, bagged lettuce, frozen green beans, vanilla ice cream, pasteurized milk, hash brown potatoes, processed frozen egg omelet, and raw bean sprouts.

The TEMPO TVC method was com-pared with the Standard Methods for the

Examination of Dairy Products (SMEDP) for milk and ice cream and AOAC Official MethodSM 966.23 for all other foods. A combination of the difference in log10 distributions and t-tests at the 5% level were used to analyze the data and com-pare performances. The TEMPO method was shown to be statistically equivalent to the reference method in both the inter-nal and independent food studies. The TEMPO TVC reagents were stable under accelerated temperature/time studies and provided highly reproducible results when compared between lots. Assay ruggedness was demonstrated for two critical parameters: incubation time and temperature of the test. Overall results indicate that the TEMPO TVC method is an acceptable alternative method for the enumeration of total aerobic bacteria in foods.

Principle of the TestThe TEMPO TVC test consists of a

vial of culture medium and a card, which are specific to this test (Figure 1). The culture medium is inoculated with the

bioMérieux TEMPO® TVC Test Granted PTM Status

A O A C R E S E A R C H I N S T I T U T E N E W SPERFORMANCE TESTED METHODSSMPERFORMANCE TESTED METHODSSM

Overall results indicate that the TEMPO TVC method is an acceptable alternative method for

the enumeration of total aerobic bacteria in foods.

Figure 1. TEMPO TVC test reagents. (Continued on page 24.)

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sample to be tested. The inoculated medium is transferred by the TEMPO Filler into the card containing 48 wells of three different volumes. The card contains three sets of 16 wells (small, medium, and large) with a one log dif-ference in volume for each set of wells. The card is designed to simulate the MPN method. During incubation, the microorganisms present in the card hydrolyze the substrate in the culture medium and cause a fluorescent signal to appear, which is detected by the TEMPO Reader (Figure 2). Depending on the number and type of the positive wells in the 3 log dilution range, the TEMPO system calculates the number of aerobic bacteria present in the origi-nal sample according to a calculation based on the MPN method.

Summary of PTM ValidationThe bioMérieux TEMPO TVC was

validated according to AOAC guidelines. This validation consisted of two main parts: internal and independent test-ing. Internal testing included studies for method comparison for 18 of the claimed matrixes, lot-to-lot and stability, and ruggedness. Independent laboratory testing included method comparison studies for four of the claimed matrixes,

including fresh raw ground beef, cooked chicken, raw cod, and raw bean sprouts. For each of the 22 foods tested in this study, three lots of each matrix and five replicates of each lot were tested for a total of 330 samples enumerated by both the TEMPO and reference plate count methods. For each lot, five 50 g samples for the AOAC Method and five 25 g samples (11 g samples for dairy) for the TEMPO TVC method were ana-lyzed for the method comparison.

ResultsMethod

Comparison: Naturally Contaminated Food Studies

The overall agree-ment within one log for the TEMPO method compared with the reference method was 97%. Regression analysis of both the internal and inde-pendent data sets is presented in Figure 3.

The mean log counts for the TEMPO TVC method were, in most cases, not significantly different from those of the ref-erence methods. The TEMPO TVC method

was shown to be statistically equivalent to the reference method in both the inter-nal and independent food studies for the enumeration of total aerobic bacteria (see Tables 1–4).

ConclusionsThe AOAC RI independent laboratory

determined that the TEMPO system could yield MPN results for total aerobic bac-teria up to 8 hours faster than the AOAC reference method. The independent labo-

A O A C R E S E A R C H I N S T I T U T E N E W S

Figure 3. Regression analysis of both the internal and independent data sets.

Figure 2. TEMPO Reading Station.

Log1

0 Te

mpo

bioMérieux TEMPO® TVC Test Granted PTM StatusContinued from page 23.

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ratory also indicated that the TEMPO system was easy to use with software that was intuitive and user friendly. Test samples could be processed in less time than the AOAC reference method.

By eliminating media preparation, serial dilutions, manual counting, and visual interpretation of results, automation of the TEMPO TVC system provides reliable, rapid results and signifi-cant economic savings in labor and increased efficiency. ■

TEMPO TVC test and system are available worldwide. For more information, visit www.bioMerieux.com and select the country of interest or type in TEMPO at the search option.

—Ronald Johnson, John Mills, and Lisa Bezzole

Contributing Writersron.johnson@na.biomerieux.com

john.mills@na.biomerieux.comlisa.bezzole@na.biomerieux.com

Mention of trade names or commercial products is for identification only and does not constitute preference over similar ones not mentioned. If you are interested in submitting an article regarding a test kit that has been granted Performance-Tested MethodSM status, contact Deborah McKenzie at dmckenzie@aoac.org.

A O A C R E S E A R C H I N S T I T U T E N E W S

Table 1. Meat log TEMPO log AOACFood Lot CFU/g CFU/g

Raw ground beefa 1 4.23 4.61 2 5.30 5.14 3 4.24 4.87

Frozen raw ground beef 1 2.55 3.14 2 3.00 3.02 3 3.62 3.89

Raw ground pork 1 3.94 4.46 2 3.55 3.51 3 5.50 5.47

Cooked roast beef 1 4.61 4.66 2 6.50 6.24 3 2.28 2.54a Independent laboratory tests.

Table 2. Poultry log TEMPO log AOACFood Lot CFU/g CFU/g

Smoked turkey 1 3.17 3.11 2 4.74 5.19 3 2.97 3.12

Fresh ground chicken 1 5.12 5.29 2 4.43 4.59 3 5.21 5.18

Frozen chicken nuggets 1 2.34 2.38 2 2.43 2.41 3 2.16 2.45

Grilled chicken 1 3.02 2.29 2 4.27 4.12 3 7.51 7.39

Cooked chickena 1 1.63 1.35 2 6.52 6.36 3 7.34 6.92a Independent laboratory tests.

Table 3. Fish and seafood log TEMPO log AOACFood Lot CFU/g CFU/g

Raw cod 1 4.09 4.31 2 3.49 4.01 3 5.88 6.07

Raw coda 1 7.46 7.72 2 7.27 7.46 3 7.31 7.18

Frozen raw catfish 1 5.24 5.08 2 3.51 3.81 3 4.27 4.58

Heat-processed fish 1 3.47 3.56 2 2.93 2.54 3 3.17 3.19

Heat-processed Crab cakes 1 2.95 2.97 2 2.55 2.79 3 3.89 3.77a Independent laboratory tests.

Table 4. Other foods (dairy, vegetables, and miscellaneous) log TEMPO log AOACFood Lot CFU/g CFU/g

Pasteurized whole milk 1 4.08 3.94 2 5.68 5.60 3 2.42 2.48

Vanilla ice cream 1 2.57 2.59 2 2.33 2.48 3 1.48 1.50

Raw bean sprouts 1 6.94 6.79 2 7.38 7.26 3 6.88 6.99

Raw bean sproutsa 1 6.64 6.88 2 7.89 8.19 3 7.95 8.09

Frozen green beans 1 2.88 2.73 2 3.01 2.91 3 3.40 3.68

Bagged lettuce 1 3.70 3.12 2 5.53 5.62 3 6.28 6.33

Frozen egg omelet 1 4.02 3.90 2 2.51 2.64 3 2.35 2.43

Hash brown potatoes 1 2.46 2.81 2 3.42 3.14 3 3.08 2.96a Independent laboratory tests.

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