A churning process with several variations that removes bacteria from food by mechanical means while adequately filtering the food matrix sufficiently for analysis in cytometer. Churning stirs, agitates, shakes, shears or compresses the food sufficiently to dislodge bacteria from food particles, without chopping, crushing, or cutting the food. In a first variation, the specimen (e.g. ground beef) is combined with water or liquid buffer, stomached, and the liquid collected for measurement in a flow cytometer. In a second variation, the specimen is combined with water or liquid buffer, vortexed and the liquid supernatant is collected for measurement in a flow cytometer. In a third variation, the specimen is combined with water or liquid buffer, placed in a sonicating water bath and the supernatant collected for measurement in a flow cytometer.