Study on total plate count detection in acid beverage by flow cytometry

Compared and analyzed with pour plate method and membrane filtration method,flow cytometer(FCM)was used to determine total plate count(TPC)for establishing a FCM method in rapid detection of TPC in acid beverage(pH＜4.6). 13 strains were selected to conduct artificial add experiment. The results showed that substrate and concentration had great influence on FCM method,some bacteria in acid beverage could not be detected by FCM method directly,which need to be filtrated on membrane and pre-enriched in neutral TSB broth at 36 ℃ for 22 h,then detected by FCM and pour plate method,results were at the same order of magnitude. The official AOAC analysis method was used to do the statistics analysis on qualitative result of 13 strains in acid beverage with different concentration detected by membrane filtration method and FCM method after pre-enrichment for 22 h,X²<3.84 and false negative rate was 1.9%<2%,false positive rate was 4.2%<9.6%,which showed that membrane filtration method could be replaced by FCM method for TPC qualitative detection in acid beverage,then used for products quick release.