The suitability of membrane filtration for detecting Pectinatus cells in filtered beer was investigated. The average recovery of Pectinatus cells was 5–19%, depending on the physiological state of the cells. Obviously, this method cannot be recommended for detecting Pectinatus in filtered beer samples. The reason for the low recovery is that most old cells, corresponding to stressed cells in practice, died during membrane filtration. The use of prereduced media or a carbon dioxide atmosphere during the procedure did not improve the recovery significantly. After forcing, direct staining of cells on the membrane by the immunofluorescence technique or by the direct epifluorescent filter technique with acridine orange gave satisfactory results. Low contamination levels (10–100 cells) could be detected after three to four days when active cells were used. With old cells, a forcing time of four to five days was needed. Direct staining revealed contamination two to four days before the beer became visually turbid. This method can be used for detecting Pectinatus contamination in different stages of bottling.
|Journal||Journal of the American Society of Brewing Chemists|
|Publication status||Published - 1985|
|MoE publication type||A1 Journal article-refereed|