Making batch 400 match batch 1

In a category where the label states a quantity, a batch that differs from the last one may not merely be inconsistent. It may be outside its own specification.

Consistency is a compliance property

The specification defines what the product is. A batch outside it is not a slightly different product; it is a product that does not meet the standard you wrote and that the label describes.

Which is why 21 CFR 111 asks for a quality unit to review and approve batches against specifications rather than leaving it to the person who made them.

Where it drifts

Raw materials. Different particle size, moisture content and impurity profile between lots, all of which change blending behavior and can change assay.

Blend time and equipment. A different blender, a different fill level, a hurried run.

Batch size, because blend time does not scale linearly and a larger batch segregates more on discharge.

The scoop, if it changes or if bulk density moves, which changes the delivered serving without changing anything on the label.

The specification is the control

Written ranges for appearance, moisture where relevant, blend uniformity, fill weight and assay where you run one. Checked every batch and recorded pass or fail.

Plus reserve samples to compare against, because numbers catch what you cannot see and samples catch what no number describes.

Holding it as you grow

Write the process as a specification: blend time, fill level, pre-blend steps, sampling points. Qualify raw material lots rather than assuming. Re-qualify after a scale-up rather than scaling the blend time arithmetically.

And recalibrate the scoop whenever bulk density could have moved, because that is the drift the customer experiences directly and nobody measures.

References