Milk and Dairy Testing
The Texas Department of State Health Services (DSHS) has strict guidelines for the monitoring of the milk and dairy industry. Samples are taken monthly to ensure adherence to these regulations and the Food and Drug Administration food safety program. The North Texas Regional Laboratory analyzes these samples and reports their findings to the state. The laboratory’s degreed microbiologists are dedicated to providing quality testing. They maintain state certifications for milk and dairy testing and routinely perform proficiency testing to ensure the public has safe dairy products.
Testing Procedures and Their Significance
State sanitarians are responsible for collecting monthly samples from regional dairies and retail milk plants for analysis. These samples are carefully monitored to arrive in the lab in a timely fashion (48 hours or less) and with a temperature of 0°C to 4.4°C maintained from collection until arrival in the lab. In order for dairies and plants to avoid off grade penalties and/or interruption in production, these samples must meet State requirements on the following tests:
Milk containing antibiotics cannot be used for human consumption. The use of milk drug residue assays insures that milk from antibiotic-treated cows is not marketed.
This test is a good indicator of added water in the milk. By using a cryoscope, the freeze point of the sample is established. The State requires any result under -.525°H be reported to them.
Somatic Cell Count
This test measures the amount of white blood cells and tissue cells in a milk sample. All milk contains some of these cells. High counts indicate a herd health problem and directly affect milk production and income. The microbiologist determines the somatic cell count by direct microscopic examination of the milk. A count above 750,000 is reported to the State and will cause a restriction on the sale of that dairy's milk.
Standard Plate Count
This is a basic quality test that is a measure of the bacteria in milk. It reveals general sanitation and herd health conditions. By use of culture technique (agar, incubation) the SPC count is assessed. This count must be less than or equal to 100,000/ml for raw milk or 20,000/g or ml for retail products. State penalties may be imposed if these counts are exceeded.
This procedure is a more specific bacterial test for the quality of the milk. It is an indicator of proper sanitation. High counts can be caused by poor herd hygiene, improperly washed and maintained equipment, or a contaminated water supply. Microbiological testing with Violet Red Bile agar enables the microbiologist to determine the coliform count. Retail products must have a coliform count below 10/g or ml to conform to State regulations. This test is not State-regulated for raw milk, but it can alert dairymen to potential problems.
This test is performed to ensure proper pasteurization has been performed on all retail products. A fluorometric procedure is used for the analysis and an alkaline phosphatase reading of less than 500mµ/L must be obtained.
Dairy Water Testing
To be suitable for use in dairy operations, water must be of a safe, sanitary quality and free of microorganisms that could initiate spoilage.
Three procedures are used in the testing of dairy waters to insure the quality of the water:
- The Coliform P/A procedure is used to detect coliform organisms in the source water used by the dairy/plant.
- Multiple Tube Fermentation (MTF) technique is used to detect coliform organisms in glycols and chill waters.
- Water Heterotropic Plate Count (HPC) is used to further analyze the quality of the dairy operation water. This can be done on both source and glycol/chill waters. Through a culture technique (agar, incubation) a count is assessed.
Acceptable limits are “no coliforms found” for the P/A and MTF procedure, and less than 500 CFU’s/ml for the HPC test.|
Special Requested Samples
The above tests are an indicator of the quality control and proper maintenance that exists in a dairy or plant situation. Results outside of the state guidelines indicate a problem and are subject to state action (i.e. warning letters, off grade status, and loss of production). Sometimes a dairyman may wish to further monitor his progress. Test results can be used as an early warning system. Problems can then be attacked in the early stages thus avoiding actionable results and state intervention. For this help, the dairyman can specially request tests be done on a sample submitted to the laboratory. This sample must be collected under sanitary conditions, kept at a temperature of 0°C to 4.4°C, and arrive in the laboratory within 48 hours. A temperature control sample must be included with the submissions. These test results will be in-house and not reported to the state. For a nominal fee, results can be faxed directly to the dairyman. The following fee schedule will be applied in this situation:
The North Texas Regional Laboratory is dedicated to providing our customers with quality services to promote and protect our community's health. It is the desire of the microbiologists in the laboratory to accomplish this by assuring the public of the safest milk and dairy supply available. Assisting the dairies with quality control is a way of achieving this goal.