High-sensitivity dry rehydratable film method for enumeration of coliforms in dairy products: collaborative study.
A dry-film coliform count plate that is inoculated with 5 mL sample was compared with the Violet Red Bile Agar plate method in a collaborative study by 18 laboratories. Products analyzed were 2% milk, chocolate milk, cream, vanilla ice cream, cottage cheese, and cheese. Collaborators tested blind duplicate uninoculated samples and samples inoculated at low, medium, and high level. Significantly (P < 0.05) higher numbers of coliforms were recovered by the dry-film method from 2% milk samples at the 3 inoculum levels, the chocolate milk at the low- and high-inoculum levels, and the cream at the high-inoculum level. Significantly higher counts were obtained by the agar method for cottage cheese samples at the low-inoculum level. The repeatability standard deviation for the dry-film method was significantly higher for the high-inoculum level chocolate milk sample and the medium-inoculum level cottage cheese. The same statistic was significantly higher for the agar method at all 3 inoculum levels in the 2% milk and the medium-inoculum level cream. The high-sensitivity dry rehydratable film method for enumeration of coliforms in dairy products has been adopted first action by AOAC INTERNATIONAL.
Curiale
M S
MS
Silliker Laboratories Group, Inc., Corporate Research Center, South Holland, IL 60473, USA.
Gangar
V
V
D'onorio
A
A
Gambrel-Lenarz
S
S
McAllister
J S
JS
D000362:Agar; D000818:Animals; D001431:Bacteriological Techniques; D002611:Cheese / Q000382:microbiology; D015169:Colony Count, Microbial / Q000295:instrumentation / Q000379:methods*; D003611:Dairy Products / Q000382:microbiology*; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D007054:Ice Cream / Q000382:microbiology; D008892:Milk / Q000382:microbiology; D014867:Water
D014867:Water; D000362:Agar