Controlling Salmonella in Low-Moisture Products

Departments - Practical QA Solutions

June 13, 2016

Salmonella has been a problem for low-moisture products for decades. The food industry has been diligent in implementing necessary controls, yet Salmonella recalls occur far too frequently. With FSMA implementation, control of Salmonella in other low-moisture products, such as specialty animal feed/food, is being challenged. “An ounce of prevention is worth a pound of cure” is a saying so true in the control of Salmonella; once it gets established in a plant environment, control becomes difficult. This microorganism can lurk in a dormant state within micro-environments and raise its ugly head with moisture and/or disturbance. Essential requirements for the control of Salmonella are:
  • Use of quality ingredients (the lower the dose, the easier the kill).
  • Establishment of an effective kill step.
  • Implementation of a primary Salmonella control area (PSCA).
  • Monitoring of zones (starting with product contact surfaces).
  • Keeping the plant dry.

10 SOLUTIONS. Following these essential requirements are 10 specific solutions.

  1. Improve process temperature verification. Actual product temperatures should be measured in the PSCA to verify the temperatures are sufficient to kill Salmonella. Establish kill temperatures and time standards throughout the PSCA. Assure that product cooling is sufficient to prevent condensation inside equipment; product temperature should be less than 20ºF. If product does not adhere to kill temperature and time, utilize an auto rework bypass or other instant correction.
  2. Establish process segregation. Segregating raw from cooked food is critical to establishing an effective PSCA. Separate with walls to control air and traffic and enhance the microbial environment. Eliminate any co-mingling of ingredients with flavor enhancements, packing supplies, and finished products.
  3. Prevent crossover microbial contamination. Although some animal-feed regulatory discretion may still exist, such discretion for human food, pet food and specialty animal food do not. If a plant is to produce a Salmonella-free product, it should have “dirty” and “clean” separation and four plant zones for cleaning and monitoring.
  4. Improve plant air flow. Air to the PSCA area should not be sourced from an ingredient or “dirty” area. A well-designed plant provides filtered air into the PSCA. Conduct an air-flow study to identify clean air source(s) and avoid dirty air. Poor air flow and lack of equipment ventilation can create other microbial problems such as mold and pest problems such as mites.
  5. Improve traffic patterns. Shoe contamination can follow employees, visitors, and contractors. Wheel contamination can follow forklifts, pallet jacks, carts, barrels, and dollies. Utilize sanitizing baths for shoes and wheels to reduce microbial transfer and prevent smaller problems from become big problems.
  6. Control process leaks and airborne dry material. Leaks cause hours of cleaning which can be seemingly unending, and are unnecessary. Some leaks create microbial and insect problems. Replace poor sanitary designs with designs that eliminate the need to clean and reduce overall cleaning time. SSOPs can be tailored accordingly.
  7. Provide access for cleaning equipment. Design and build safe, quick equipment access which is critical for cleaning PSCA zones 1 and 2. Target problematic areas: legs, flavoring applications, coolers, transitions, conveyors; known trouble areas such as coolers; and those indicated by a microbial-monitoring program.
  8. Establish an effective cleaning organization and utilization of human resources. Establishing an effective cleaning program requires directional leadership, procedure development (SSOPs), employee training, cleaning supervision, and timely evaluation. Reducing the plant to manageable areas, with each area having a food safety leader (FSL) is a means to an organized, effective cleaning program. Provide a FSL reporting structure to the chief food safety officer for an efficient utilization of “production” labor, especially during clean-break time.
  9. Improve overall cleaning program. A thorough cleaning program must be established for all zones, with zones 1 and 2 on a clean-break program and zones 3 and 4 on a master sanitation schedule (MSS). All cleaning programs should be developed with science and history to maximize efficiency, effectiveness, and overall performance. Cleaning procedures (SSOPs) must be utilized to achieve a desired level of clean.
  10. Establish an integrated pest management program (especially for flies). Insects are a symptom of an issue with exclusion, sanitation, and/or air flow, and flies a sign that something worse is lurking. Flies in the PSCA are unacceptable and one fly is one fly too many. Insects, rodents, and birds are known sources of Salmonella contamination.

These requirements and 10 solutions summarize what it takes to control Salmonella in low-moisture food, animal/pet food, and feed-milling operations. This list can be used for Salmonella-control troubleshooting. To implement a successful microbial control program, these items should be individually addressed as part of an overall strategic plan to be incorporated into short-term action and long-term budgeting.

Controlling Salmonella requires a well-planned microbial control program. An excellent Salmonella-control form is available from GMA at

Ole Dosland is QA & Food Safety Consultant and Trainer, DOZ Enterprises.