Membrane Filters

- food sample pre-filtered to remove large particles (10 um pore) - sample goes through 0.22/.45/.6um filter that allows diluent to pass and retains bacteria - filter is stained and examined microscopically or placed on agar for colony formation - techniques: direct epifluorescent filler technique (DEFT), microcolony DEFT, and hydrophobic grid membrane filter (HGMF) technique