A-plate loop count method for determining viable counts of pasteurized milk products is described. The technique uses a 0.01 ml calibrated platinum alloy loop attached to a continuous pipetting syringe for rinsing the 0.01 ml of sample into a petri dish with 1 ml of sterile buffered dilution water prior to pouring with agar. Results with this method indicate that accuracy within ± 15 percent is attainable on samples of skim, 2 percent, homogenized, whole milk, and half and half. Measurements of chocolate milk were not accurate.

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Author notes

1Work on this project was initiated while the senior author was on active duty as an army reserve officer at the Robert A. Taft Sanitary Engineering Center. The experiments were completed at the Wisconsin State Laboratory of Hygiene, Madison.

2Official laboratory for the Wisconsin State Board of Health.