3 Steps for All-Inclusive Control of Spores

There is no silver bullet when it comes to spore control. It takes an all-inclusive approach on the farm, in the plant and while cleaning.

Food processors around the world are increasingly demanding tighter ingredient specifications and consistent ingredient performance to meet new product developments as well as plant and equipment upgrades—not to mention withstand challenging distribution and storage conditions.

Milk powder specifications and specifically spore levels have been barriers to expanding trade in certain application segments. That was particularly the case in Southeast Asia, where end users cited inconsistencies and lax specifications in some U.S. products. Spores—which can significantly affect product quality and lead to taste, texture and appearance defects—were at the center of those criticisms. 

The U.S. Dairy Export Council (USDEC), working closely with Dairy Management Inc. (DMI), has been a leader in framing and addressing the problem.

USDEC’s goal was to help manufacturers understand how and where spore-formers entered into the milk and where they multiplied during processing, and then outline practical methods to control levels.

There is no silver bullet when it comes to spore control. It takes an all-inclusive approach that includes three key steps:

1. Minimizing spore ingress at the farm.
2. Keeping the levels as low as possible during processing through:

• Simple plant and equipment design to help streamline the process.
• Minimizing milk residence time at temperatures that favor thermophile and thermophilic spore-former growth 40-70ºC (104-158ºF).
• Prevention of fouling and biofilm formation. Minimizing surface areas where biofilm can build up and subsequently release bacteria in the product.

3. Implementing an effective cleaning system to remove residual product, fouling and microbes, including spore-formers. This will minimize re-contamination from run to run.

A September 2014 spore seminar, conducted by USDEC and DMI, highlighted a breakthrough in cleaning from food plant hygiene company Ecolab. Ecolab developed a new cleaning-in-place protocol that uses additional cleaning and sanitizing solutions that appear to more effectively remove fouling and biofilms and inactivate spores.

The program allows plants to run for more than 20 hours while maintaining spore counts of less than 1,000 colony-forming units per gram (CFU/g), which is considered low-spore powder by some of Southeast Asia’s processors. That translates to 3-4 times more low-spore powder than a plant typically produces. It also enables a plant to make as much as 8 times the amount of powder at spore counts of less than 300 CFU/g.

The program proves that milk quality improvement efforts do not necessarily require heavy equipment investment.

The industry has recognized the spore issue. The awareness is there. All the major players have done their internal assessments and some are excelling at creating low-spore powder.

Moving ahead, the effort will analyze on-farm practices to minimize spores entering raw milk, and transition into a broader program that looks at other aspects of milk powder functionality, including solubility, heat stability, flavor and shelf life.

We are also seeking to ensure that all milk powder products—from any producer in the world—get measured equitably.

There currently are several methods to enumerate spores, so final counts often differ by the test used. The International Spore Testing Consortium, a group led by NIZO Food Research in partnership with USDEC and major dairy processors and ingredient users from around the world, seeks to determine an improved method to count heat-resistant spores and possibly enumerate particular species.

The spore seminar showcased the latest breakthroughs in helping manufacturers control spore-formers through in-plant procedures, equipment and technology, and cleaning. It also demonstrated the impact of test methods on spore counts.

That seminar not only unveiled new options for controlling spores, it showed that U.S. processors are building on these foundations and implementing new practices to increase the volume of low-spore, high-spec milk powder. 

Ongoing research and collaboration have helped frame and address the spore issue, providing a foundation on which U.S. processors could build better milk powder quality programs. We intend to provide the materials to help them keep building.

The U.S. Dairy Export Council is primarily supported by Dairy Management Inc. through the dairy farmer checkoff that builds on collaborative industry partnerships with processors, trading companies and others to build global demand for U.S. dairy products.