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

The FDA doesn’t guess where contaminated food came from. It follows a trail - and the key to that trail is the lot number. Since the Food Safety Modernization Act (FSMA) took effect, every high-risk food item in the U.S. supply chain must carry a unique Traceability Lot Code (TLC). This isn’t just a label. It’s a digital fingerprint that lets the FDA trace a contaminated batch from your grocery shelf all the way back to the farm, packing house, or processing plant - in hours, not weeks.

Why Lot Numbers Matter More Than Ever

Before the FDA’s Traceability Lot Code system, tracking a foodborne illness outbreak was like searching for a needle in a haystack blindfolded. Investigators had to call dozens of suppliers, sift through paper records, and piece together shipping logs. During the 2018 E. coli outbreak linked to romaine lettuce, it took over six weeks to pinpoint the source. By then, thousands were sick, and millions of pounds of produce were destroyed unnecessarily.

The TLC system changed that. Now, when someone gets sick from contaminated food, the FDA can request electronic records from any company in the chain. Within 24 hours, they get back the lot number, where it came from, where it went, and how much was shipped. That’s the difference between a slow, costly investigation and a fast, targeted recall.

What Exactly Is a Traceability Lot Code (TLC)?

A TLC is an alphanumeric code assigned to a specific group of food items - a lot - that shares the same origin and handling history. It’s not the same as a company’s internal batch code. The FDA requires it to be unique across the entire supply chain, not just within one company’s system. Think of it like a passport number for a shipment of food: once it leaves the source, that number travels with it until it reaches the consumer.

The FDA doesn’t dictate how the code is created. A company can use a Julian date + product code (like 2025001-LG02), a random string (like X7K9P2-MN), or even their existing internal lot number - as long as it’s consistent and traceable. The key is documentation. Every company must keep a written Traceability Plan explaining how they assign and track these codes.

Where and When Lot Numbers Are Assigned

You can’t just slap a TLC on a product anytime you want. The FDA sets strict rules for when it must be applied:

• At the first point of packing for raw agricultural commodities (like lettuce, tomatoes, or onions) - usually the farm or packing facility.
• At the first land-based receipt for seafood caught at sea - meaning the first time it hits U.S. soil after being caught.
• When food is transformed - like when tomatoes are turned into salsa, or milk is made into cheese.

Once assigned, the TLC stays the same unless the food is changed. If a processor takes in 10 different lots of lettuce and mixes them into one bag of salad, they must create a new TLC for the new product - but they must also record which original lots were used. This creates a chain of custody that’s impossible to fake.

The Seven Key Data Elements That Make It Work

A TLC alone isn’t enough. The FDA requires it to be linked to seven specific pieces of information, called Key Data Elements (KDEs). These are the details that turn a code into a live trail:

• Traceability Lot Code (the code itself)
• Product description (what the food is)
• Quantity and unit of measure (how much was shipped)
• Location where the TLC was assigned (the facility address)
• Transaction information (who sent it, who received it, and when)
• Common name of the food (as defined by FDA)
• Form of the food (whole, chopped, frozen, etc.)

These KDEs must be recorded and kept for two years. If the FDA asks for them during an investigation, companies must deliver them electronically - in a format like CSV or Excel - within 24 hours. Paper records won’t cut it anymore.

Which Foods Are Covered?

Not every food needs a TLC. The FDA created a Food Traceability List (FTL) of high-risk items that cause the most outbreaks. These include:

• Leafy greens (romaine, spinach, kale)
• Tomatoes
• Onions
• Fresh-cut fruits and vegetables
• Soft cheeses (like brie or queso fresco)
• Shell eggs
• Nut butters
• Specific seafood (like shrimp, crab, and tuna)

These foods make up about 15% of the U.S. food supply by volume - but they’re responsible for nearly 70% of foodborne illness outbreaks. The list isn’t set in stone. The FDA is actively reviewing whether to add melons, sprouts, and ready-to-eat meals in the next phase.

How Companies Are Adapting

Most large food companies already had traceability systems in place. Walmart, for example, required blockchain-based tracking for leafy greens as early as 2019. But for smaller farms and processors, the change has been costly and complex.

A 2023 survey found that 78% of produce companies had already updated their systems to meet TLC requirements. The average cost per company was $42,500. Many used existing ERP software (72%), while others bought specialized traceability tools (21%). A small number still rely on spreadsheets - but that’s risky. The FDA requires records to be sortable and exportable. A handwritten log won’t cut it.

The biggest hurdles? Integrating old systems (65% of companies report issues), training staff (58%), and making sure suppliers all use the same standards (71%). The FDA has responded with 12 free training modules and a Traceability Assistance Program for small businesses.

What Happens When a Problem Is Found?

Imagine a customer in Chicago gets sick from Salmonella in packaged salad. The CDC reports the case to the FDA. The FDA pulls the product’s UPC and matches it to the lot number on the package. They then request the KDEs from the processor. Within hours, they know which farm supplied the lettuce, which packing house mixed it, and which distributors shipped it. They issue a recall for only that specific lot - not every bag of salad on the shelf.

That’s the power of the TLC. In pilot tests, the FDA reduced outbreak response time from 14 days to under 24 hours. They estimate this could cut foodborne illnesses by 20-30% annually - preventing tens of thousands of cases and saving $60 million in healthcare and lost productivity costs.

Challenges and Criticisms

The system isn’t perfect. Critics say the Food Traceability List is too narrow. Consumers Union pointed out that melons, which caused a deadly Listeria outbreak in 2020, aren’t included. Others worry about data silos - if every company uses different software, the records might not talk to each other.

Industry groups also raised concerns about "tandem coding" - having to run both an internal lot code and a TLC. The FDA clarified in its final rule: your existing code can be your TLC, as long as it meets the requirements. No need for double work.

Another issue: compliance is delayed. The original deadline was January 20, 2026. But after industry pushback, the FDA proposed pushing it to July 20, 2028. That gives small businesses more time - but it also means the system won’t be fully active for another three years.

The Bigger Picture

The TLC system is the biggest upgrade to U.S. food safety since the Bioterrorism Act of 2002. It’s not about controlling every step of the supply chain - it’s about making sure the right data is there when it matters most.

Internationally, the EU is moving toward Digital Product Passports with different standards. The FDA is now talking to global regulators to align systems. Without that, U.S. exporters could face barriers abroad.

Meanwhile, new tech is coming. The FDA is funding pilot projects using IoT sensors and blockchain to track temperature and handling conditions in real time. The goal isn’t just to trace a problem - it’s to prevent it before it happens.

What This Means for You

If you’re a consumer, this system means fewer contaminated products on shelves. Fewer recalls. Faster answers when something goes wrong. You’ll never see the TLC on your packaging - but you’ll feel its effect when a foodborne illness outbreak is contained before it spreads.

If you’re in food production or distribution, compliance isn’t optional. The FDA has enforcement power. Non-compliant companies can face fines, import holds, or even shutdowns. But the long-term payoff is clear: trust from retailers, fewer losses from unnecessary recalls, and a stronger reputation in a market that demands transparency.

What’s Next?

The FDA plans to expand the Food Traceability List in 2025-2026. Melons, sprouts, and ready-to-eat meals are under review. They’re also working on standardized data formats to make record-sharing easier across systems.

The goal? A food system where a single contaminated item can be traced and removed before it reaches thousands of people. The lot number is the thread that holds it all together.