SHORT-TIME MEMBRANE FILTER METHOD FOR ESTIMATION OF NUMBERS OF BACTERIA1

Abstract

Directions are given for the 8- to 12-hr membrane filter-colony technique for the estimation of numbers of viable bacteria in rinsings or swabbings from the surfaces of foods or equipment. Tests on 6 species of bacteria often found in foods demonstrated good recovery of organisms from pure cultures or mixtures of 2 or 3 cultures. Tests with dairy rinses and fresh green beans and sweet com gave counts almost as high as by the 48-hr plate, count. Results with frozen or blanched and frozen beans and corn and with chlorinated flume waters were unsatisfactory.