Pasteurization of raw milk was introduced to extend product shelf life and destroy pathogens. The measurement of alkaline phosphatase (ALP) activity has been used as an indicator of proper pasteurization in dairy products for more than 65 years. This study was undertaken to evaluate six different fluid dairy products at lower phosphatase levels than previously verified using the Fluorophos Test System, a sensitive and precise method for ALP activity detection. Thirteen laboratories participated in this collaborative, international study to evaluate the fluorometric test at 20, 40, 100, 350, and 500 mU/liter and extend the scope of the method to include milk from not only cows but also goats and sheep. Initially, the statutory level of ALP measured fluorometrically was set to equivalent levels of colorimetric test standards (500 mU/liter). The European Union recently announced its intention of lowering the legal limit from 500 to 350 mU/liter and, in addition, setting a target value of 100 mU/liter, which if exceeded would trigger an investigation into the pasteurizer plant performance. At 500 mU/liter of ALP, this trial generated relative standard deviation of repeatability values of 6.48, 5.69, and 1.74% and relative standard deviation of reproducibility values of 14.66, 13.30, and 5.33% for all cow's, sheep's, and goat's milk samples, respectively. Data from this study are comparable to data from previous studies and indicate the suitability of the Fluorophos Test System method for measuring ALP activity in milk from cows, sheep, and goats not only at the current European statutory level of 500 mU/liter but also at much lower levels.

The repeatability data are in accordance with data obtained on clinical osmometers with use of larger sample sizes. All 4 samples tested on the tear osmometer have osmolality values that correlate well to the clinical instrument method. The tear osmometer is a suitable instrument for testing the osmolality of microliter-sized samples, such as tears, and therefore may be useful in diagnosing, monitoring, and classifying tear abnormalities such as the severity of dry eye disease.

This study compared colony counts of mixed bacterial cultures on chromogenic spread plates using manual and Color QCount (Spiral Biotech, Inc., Norwood, MA) PRACTICAL APPLICATIONSA variety of microbiology applications require users to count bacterial colonies on agar plates. Colonies are counted to 1) assess levels of contamination in the environment, water, food and dairy products; 2) conduct preservative and efficacy studies; and 3) determine the quality of pharmaceutical and medical products with microbial limits testing. There are several sources of variability in plating including inoculating errors, sampling errors, incubation errors, and counting errors. Errors in counting may worsen with user fatigue.