Lot Number Tracking: How the FDA Identifies Problem Batches in the Food Supply

The FDA doesn’t wait for hundreds of people to get sick before acting. When a foodborne illness outbreak hits, time is everything. A single contaminated batch of spinach or peanut butter can spread across dozens of states in days. That’s where lot number tracking becomes the difference between a contained incident and a nationwide crisis.

What Is a Traceability Lot Code (TLC)?

A traceability lot code (TLC) is a unique identifier - usually a mix of letters and numbers - assigned to a specific group of food products at key points in the supply chain. It’s not just any lot number you might see on a jar of peanut butter or a bag of lettuce. This is a government-mandated system designed to trace food from farm to table in hours, not weeks.

The TLC is the core of the FDA’s Food Traceability Rule, part of the Food Safety Modernization Act (FSMA) finalized in November 2022. It applies to foods on the Food Traceability List (FTL), which includes high-risk items like leafy greens, tomatoes, onions, fresh-cut fruits and vegetables, certain cheeses, eggs, nut butters, and specific seafood. These foods make up about 15% of the U.S. food supply but are linked to the majority of foodborne outbreaks.

Unlike old-style lot codes, which companies used internally for quality control, the TLC must be passed along every step of the way. Once assigned, it stays with the product unless the food is transformed - say, when raw tomatoes are turned into salsa. At that point, a new TLC is created, but it must still link back to the original.

How the FDA Uses TLCs to Track Contamination

When someone gets sick from contaminated food, public health officials start asking: Where did this come from? Which batch? When was it packed? Who shipped it?

Before the TLC system, investigators had to call dozens of companies, dig through paper records, and piece together shipping logs. It could take weeks. Now, if the FDA requests data during an outbreak, companies must provide all seven Key Data Elements (KDEs) linked to the TLC within 24 hours. These include:

• The traceability lot code itself
• Where and when the code was assigned
• Product description
• Quantity and unit of measure
• Transaction information (who sent it, who received it)
• Location of each handling event
• Any previous TLCs the product came from

This creates a digital trail. If contaminated lettuce is found in a salad at a restaurant in Chicago, the FDA can trace it back to the farm in California, the packing facility in Arizona, and the distributor in Illinois - all within a day.

Where and When TLCs Are Assigned

You can’t just slap a TLC on a product whenever you want. The FDA requires it to be assigned at three specific points:

1. When raw agricultural commodities (like lettuce or onions) are first packed - except for seafood from fishing vessels.
2. When seafood from fishing vessels is received on land for the first time.
3. When food is transformed - meaning its physical state changes, like when eggs are turned into liquid egg product or nuts are ground into butter.

This forces accountability at the source. If a batch of spinach is contaminated, the TLC tells you exactly which field it came from, which harvest date it was picked, and which truck carried it out. No more guessing.

Flexibility in Code Design - But No Room for Error

The FDA doesn’t dictate what the TLC looks like. A company can use a Julian date + product code (like “2025045-LG12”), a random alphanumeric string, or even their existing internal lot code - as long as it’s unique and traceable.

But here’s the catch: the code must be usable across the entire supply chain. A code that works for one company’s warehouse might not be readable by a distributor’s system. That’s why the FDA encourages electronic records in formats like CSV or JSON, which can be easily shared and searched.

Many large companies have already upgraded their ERP systems to handle TLCs. Smaller farms and processors are using simpler tools - even spreadsheets - as long as they can produce the required data on demand. The FDA offers free training modules and technical help through its Traceability Assistance Program for small businesses.

Why This System Is a Game-Changer

The old system was like trying to find a needle in a haystack while blindfolded. The TLC system turns that into a GPS search.

The FDA estimates that faster traceability could reduce foodborne illness outbreaks by 20-30%. That’s tens of thousands of fewer sick people every year. In pilot programs from 2019 to 2021, companies using TLCs were able to trace contaminated products in under 24 hours - compared to 7-14 days before.

Retailers like Walmart and Kroger have gone even further, using blockchain to track leafy greens in real time. But the TLC system is the baseline - the minimum standard that every food handler must meet.

Challenges and Criticisms

It’s not perfect. Some companies complain about “tandem coding” - having to maintain both their internal lot codes and the new TLCs. But the FDA clarified early on: your existing code can be your TLC, as long as it meets the rules.

Others argue the Food Traceability List is too narrow. Melons, for example, have been linked to outbreaks but aren’t included yet. Consumers Union and other groups say that’s a dangerous gap. The FDA agrees - Commissioner Robert Califf has said melons and ready-to-eat foods are under active review for inclusion.

Another issue: interoperability. If one company uses a barcode, another uses a QR code, and a third uses a manual log, data can get stuck in silos. The FDA is working on standardized electronic formats, with a draft expected in mid-2024.

Compliance Timeline and Real-World Impact

The rule became effective in December 2022, but companies had until January 20, 2026, to comply. In September 2023, the FDA proposed pushing that deadline to July 20, 2028 - a 30-month extension - after hearing from small businesses that they needed more time.

As of early 2025, about 78% of larger produce companies have already adjusted their systems. But only 42% of small and medium businesses know the requirements exist. That’s why the FDA is ramping up outreach, and why the 2023 Farm Bill included $25 million in grants to help small farms implement TLC systems.

The market for food traceability tech is booming - projected to grow from $1.87 billion in 2022 to over $4.6 billion by 2028. That growth isn’t just about compliance. It’s about trust. Consumers want to know their food is safe. Retailers want to avoid recalls. And the FDA wants to stop outbreaks before they spread.

What This Means for You

If you buy fresh produce, eggs, or nut butter, this system protects you. When a recall happens, you’ll see it faster. The affected lot numbers will be published quickly because the FDA can pinpoint them in hours, not days.

You might not see the TLC on your package - it’s often buried in shipping documents or digital records. But it’s there. And when something goes wrong, it’s the reason the FDA can act before you or your family get sick.

This isn’t just bureaucracy. It’s a safety net woven into the food supply - one lot code at a time.