FAQ (Testing / Inspecting / Counting)
Q: What is the procedure for bacterial testing with DOX?
Take the following three steps:
(1) Adjust sample solution.
(2) Dispense dedicated culture medium and sample solution into dedicated cell cartridge.
(3) Set in the main unit.
See Manual Videos for details.
Q: What is a culture medium?
It is a substance that contains nutrients necessary for bacteria to grow, and is used to incubate bacteria.
Q: How should culture media and cell cartridges be stored?
Cell cartridges should be stored at room temperature, and culture media should be stored in a refrigerated space below 10°C but without freezing.
Q: Is it necessary to count both total viable cells and coliforms?
Total viable cells are an indicator of the hygienic handling of food in general. Coliforms are an indicator of whether heated food has been adequately heated and whether any cross-contamination has occurred after heating. Since the counts have different purposes, the final decision is left to the customer.
Q: Our abnormality criterion value is set at 100,000 total viable cells/g. How long will it take to complete the analysis?
Approximately 5-6 hours, depending on how the food is processed.
Q: How long will it take to confirm that there are no coliforms?
Approximately 18 hours, depending on how the food is processed.
Q: What is a calibration curve?
It is a formula (graph) that converts the time of bacteria detection (by DOX) into the number of bacteria.
Q: Why does the calibration curve vary from sample to sample?
Different types of food (for example, meat, vegetables, and fish) have different kinds of bacteria. Also, the condition of the bacteria will vary according to how the food was processed. The bacteria will multiply at different rates according to their type and condition, so a calibration curve appropriate for each is needed.
Q: Can I also test by a smear method?
Yes, by preparing 1 ml of test solution using a commercially available smear kit or similar.
Q: What is a smear method?
This test is performed by wiping a fixed area with cotton swabs containing diluent and counting the number of bacteria on the swabs in order to check for contaminated floors, walls, surfaces of manufacturing machines, and surfaces of workers’ fingers.
Q: What is a stomacher?
It is a machine that finely beats, crushes, and stirs food. To count the number of internally-lurking microorganisms, the food must be finely crushed and stirred with a diluent.
Q: What is a rinse?
The rinse method is a way to wash bacteria off the surface of food. When a stomacher is used, components may seep out with some foods, making it impossible to count the bacteria accurately. The rinse method may be used in such cases.
Q: Does pH affect counts?
Acidic (pH 3 or lower) substances cannot be counted by DOX because bacteria will not grow in them.