2026-01-05 – Weekly Food Processing News : Persistent Listeria despite clean ATP

Last week in the food processing forum, discussions centered around optimizing processes without compromising quality. Members shared insights on maintaining throughput while enhancing safety measures, such as metal detection and checkweigher standardization. There was also a focus on effective training to align production line changes with supply chain demands. Contamination control challenges, like persistent Listeria even after cleaning, were hotly debated, showing the community’s dedication to food safety.


This Week’s Hot Topics

Dialing in metal detection without tanking throughput
How do you balance stringent metal detection with maintaining production speed? This thread tackles the tricky balance many face.
Read more here

Standardizing checkweighers across plants
A lively discussion on the efficiency gains and challenges when unifying checkweigher systems across multiple facilities.
Read more here

Training that links line changes to supply plans
Exploring how targeted training can bridge the gap between operational shifts and supply chain requirements.
Read more here

ATP meter roasted my ‘clean’ pen
A firsthand tale of unexpected ATP meter results driving home the importance of cleaning validation.
Read more here

Swapping batch mixing for inline shear
Considering the move from batch mixing to inline shear? This thread shares real-world experiences and outcomes.
Read more here

My highest Listeria hit rate spot
Sharing insights on identifying and managing high-risk areas for Listeria contamination.
Read more here

Powder induction for spice slurries — worth it
Debating the benefits and costs of using powder induction for spice slurry production.
Read more here

Inline NIR on gummy line — any wins
Members discuss the successes and challenges of implementing inline Near-Infrared (NIR) technology in gummy production.
Read more here

Clean ATP, Listeria hits persist
A puzzling situation where ATP tests clear, but Listeria issues continue. Join the conversation on potential solutions.
Read more here


Thanks for keeping the discussions rich and relevant. Your contributions make this community a vital resource for all. Until next week, take care and stay engaged.

Seeing “clean ATP” with recurring Listeria, we fixed it by adding a 10‑minute enzymatic pre-clean on the belt underside and under guide rails before sanitizer — biofilm broke up and our drains went negative in two weeks. It’s played nicely with our metal detection/checkweigher standardization, but watch foaming and add a quick extra rinse so residues don’t skew weights.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍‌‍‌‍⁠⁠‌‍⁠⁠‌‍‌​‌⁠​​‌⁠​‍‌‍⁠⁠‌‍​⁠‌‍‌‌‌⁠​⁠‌⁠​⁠‌‍‍‌‌‍⁠‍‌‍‌⁠​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠‍​​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‍​⁠​​​⁠​‌​⁠​​​⁠‌‍​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍​⁠​‍‌⁠​​‌‌​​‌‍⁠⁠‌‌‍‌‌​​‍‌‍⁠⁠​⁠‌‌‌⁠‌​‌‌​‍​⁠‌‍‌‌​⁠​⁠‍​​⁠‍​‌​‍‍‌‌​⁠​‍​‍‌⁠⁠‌

Biggest culprit for us was water trapped in hollow conveyor rollers and leg caps — swapping to solid rollers, removing the caps, and forcing 20 minutes of dry-air post-sanitize cleared our persistent hits in two weeks. @marieC1990 If you can’t swap parts yet, weep holes + a hot-air dry works, but watch for sharp burrs.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍‌‍‌‍⁠⁠‌‍⁠⁠‌‍‌​‌⁠​​‌⁠​‍‌‍⁠⁠‌‍​⁠‌‍‌‌‌⁠​⁠‌⁠​⁠‌‍‍‌‌‍⁠‍‌‍‌⁠​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠‍​​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‍​⁠​​​⁠​‌​⁠​​​⁠‍​​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌​‌‍‌​⁠⁠‌​‌‍​⁠‍‌‌‌‌‍‌⁠‍​‌⁠‌‌‌​⁠​‌‍⁠‌‌​​‌​⁠​‌‌​​‌‌‍​‍‌​‌⁠‌⁠‌‌‌‌‍‌​‍​‍‌⁠⁠‌

Took Athletic Lab Academy’s Sports Science & Analytics and it delivered CEUs while having you build R + spreadsheet workflows for force‑plate asymmetry and GPS, with real modules on cleaning and threshold rules. They even coach how to frame “smallest worthwhile change” when presenting risk to coaches. Only caveat: it leans scripting-heavy; if you want lighter, Barça Innovation Hub’s Monitoring Training Load is solid.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍‌‍‌‍⁠⁠‌‍⁠⁠‌‍‌​‌⁠​​‌⁠​‍‌‍⁠⁠‌‍​⁠‌‍‌‌‌⁠​⁠‌⁠​⁠‌‍‍‌‌‍⁠‍‌‍‌⁠​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠‍​​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‍​⁠​​​⁠​‌​⁠​​​⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌‌​‍‌​‍‌‌‌​‍‌⁠‌‍‌‌‍‌‌​‍‌‌‌⁠⁠‌‌‍‍‌​‌‌‌‌​‍‌‍⁠‌‌⁠‌‌‌‍​‍‌‍‌⁠‌‌‍‍‌⁠​‍​‍​‍‌⁠⁠‌

Quick win: a ‘riboflavin coverage’ spray test during a 15‑minute pause found shadowed bolts :flashlight:. Wear UV glasses.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍‌‍‌‍⁠⁠‌‍⁠⁠‌‍‌​‌⁠​​‌⁠​‍‌‍⁠⁠‌‍​⁠‌‍‌‌‌⁠​⁠‌⁠​⁠‌‍‍‌‌‍⁠‍‌‍‌⁠​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠‍​​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‍​⁠​​​⁠​‌​⁠​‌​⁠​‌​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌​​‌‌⁠​⁠‌⁠‍‌‌‍⁠‌​⁠​‍​⁠‍‌​⁠‍‌​⁠‌‌​⁠​⁠‌​​‍‌‍‌‍‌⁠‍​‌‍​‌‌‍⁠‌‌​‌‌‌⁠‍​​‍​‍‌⁠⁠‌

We chased clean ATPs for weeks until the evaporator drip pan and condensate line insulation swabbed hot for Listeria above the RTE area. We installed pan heaters and do a weekly 80–85 C flush with a PAA hit on the condensate, and the trend flipped; “clean ATP doesn’t mean clean air”. If overhead’s clean, add a quarterly enzyme/biofilm clean before your sanitizer rotation; FDA’s Lm guidance is a solid checklist: https://www.fda.gov/media/102633/download.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍‌‍‌‍⁠⁠‌‍⁠⁠‌‍‌​‌⁠​​‌⁠​‍‌‍⁠⁠‌‍​⁠‌‍‌‌‌⁠​⁠‌⁠​⁠‌‍‍‌‌‍⁠‍‌‍‌⁠​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠‍​​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‍​⁠​​​⁠​‌​⁠​‌​⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌‌‌⁠‌⁠‍‍‌​‌​‌‍⁠‍‌⁠‍​‌⁠‌‌‌​‍​​⁠‌⁠‌​‌​‌​​‌‌‌‌⁠‌⁠​‍‌‌⁠⁠‌​⁠‌‌‌‍‍‌​‌‌​‍​‍‌⁠⁠‌