Batch numbers explained: why repacking creates a new batch

What the law requires

• Prepacked food, including supplements, must carry a lot mark identifying the batch it belongs to (Food (Lot Marking) Regulations 1996).
• The lot mark is usually preceded by “L”, unless it is clearly distinguishable from other information.
• You decide what counts as a lot: units produced, manufactured or packed under practically the same conditions.
• It can be left off if the best before date shows at least the day and month uncoded, or if the largest side of the pack is under 10 cm², but most brands still use one.

Why 15 kg becomes 300 g under a new batch

When an ingredient or finished powder arrives in a 15 kg sack, the sack carries the supplier's batch number. Packing it into 300 g tubs is a new operation, on a different day, on your line, with your packaging. Those tubs form a new lot, so they get your own batch number.

What matters is the link. Your records must show which supplier batch, or batches, went into each of your batches. If one tub run uses two different sacks, the records need to show both. That is “one step back, one step forward” traceability, which food law requires.

Good practice

• Keep batch records linking supplier lots, packing date, line and quantities.
• Print the batch and best before at packing. A reserved space on the proof is fine.
• Use a format your team and your customers can read, for example L + date + line.