In today’s competitive marketplace, it has become essential to extend the shelf life of dairy products beyond the traditional 14- to 16-day code dates. Ever-increasing distribution distances and high customer demands have greatly contributed to this need. Is 18 to 21 days shelf-life an attainable goal and should dairy plants be striving for this longer shelf-life?

The answer is “yes” and “yes;” however, test results indicate that approximately half of all dairy plants in the United States have not achieved this goal. In fact, many plants have difficulty reaching a shelf-life of 14 to 16 days.

Should we be willing to accept this kind of mediocrity, or are there steps we can take to change this culture in the dairy industry?

Here are a few basic rules to help identify where you are and how to tackle this very important issue:

Make sure you have a high-quality raw milk supply. The following tests are recommended on incoming milk to ensure quality.

  • Direct Microscopic Count (DMC). This is the one test that dairy processors run on each tanker of raw milk that will give an idea of the microbiological quality of the raw milk prior to unloading. The goal should be a count of < 50,000 clumps / mL.
  • Preliminary Incubation Count (PI). A very valuable test to help indicate the overall quality of raw milk supply. It is especially useful at detecting raw milk that has been contaminated, stored under improper cooling and/or unsanitary conditions. Goal is a count of < 50,000 cfu / mL.
  • HR-3 Test results. Results should be negative to ensure minimal Gram positive sporeformers are present (the slower growing sporeformers are a big detriment to extended shelf-life).
  • Sensory Evaluation. There should be no detectable off-flavors or odors.
  • Temperature Control. Temperature of raw milk is critical and must be received and maintained at ≤ 40°F.

Know your actual product shelf-life. Accurate and systematic shelf-life testing is necessary before extending the code life of dairy products. Shelf-life determined at 45 degrees F is the ultimate quality test. Taste the product at 14 to 16 days, and if the flavor is good, taste it again at 18 days. Strive for a shelf-life goal of 95% good at 18 days. Once this goal is achieved, then work towards 21 days.

Now comes the difficult part. Where do you look, and how do you find the problems affecting shelf-life? The best strategy may be “inspecting, sampling and testing” throughout your facility. Sampling and testing methods are not new to the industry. Unfortunately, not all plants use these methods. Or, if they do, they may not be reacting correctly to the results. There are a variety of sampling and testing methods available.

  • Sample ports are recommended to collect line samples for tracking product quality through processing, storage and packaging. There are different sample ports in use today, and what is important is knowing how to use and care for them. Even more important is how you interpret and use the results.
  • Actually inspecting equipment, taking swab samples and conducting ATP bioluminescent testing are effective methods of locating improperly cleaned surfaces, which can then be re-cleaned prior to start-up.
  • After inspecting equipment that has been cleaned and sanitized and found to be suspect, take a swab sample and run Total Coliform and SPC tests. These tests may produce unexpected results and can also help pinpoint areas that require more attention.
  • Here are a few “rocks” under which you might want to look to identify problem areas:
  • Air-blow fittings. It may not be enough to just change the filter after CIP. Swab inside the fitting and you might be surprised what you find.
  • How often are you checking door gaskets? Look for cracks and deterioration where bacteria can harbor. Swab the inner lip of door gaskets.
  • When parts and fittings are placed in the COP tank, are they broken down completely? Are parts placed properly in the COP tank for good cleaning circulation? Inspect the parts after cleaning and take swab samples for testing.
  • Check pump seals for leaks. If milk can leak out, bacteria can leak in. Break down the leaking pump after cleaning and take swab samples to test around the seal.

These are just a few of the many areas in a plant where unexpected issues can be found that affect your product shelf-life. By paying attention to seemingly minor points, you can ensure that the actual shelf-life meets the code date of the products.  

For More Information

Learn more about Randolph Associates Inc.’s training programs, products and technical expertise by visiting the company website at Sign up for the following training courses:

  • Dairy Technology Workshop, March 24 to 27
  • HACCP Certification Course, April 7 to 9
  • Implementing SQF Systems, April 9 to 11

 For registration and additional information, contact Kristy Clark at 205-595-6455 or email