The critical factors, and holding them

A scheduled process is not one number. It is a set of conditions that together make the product safe, and each of them is a thing you have to hold every batch.

What a critical factor is

A condition the process authority has determined must be controlled for the process to deliver a safe product. The scheduled process must include the information essential to producing a safe product, including the maximum equilibrium pH and other critical factors such as heat processing and any preservatives used and their levels.

They are not guidelines and they are not a recipe. Departing from one is a deviation.

The usual ones

Maximum equilibrium pH, and the time within which it must be reached.

Acid type and level, because different acids behave differently and the process was validated with one.

Fill temperature and hold time for a hot-filled product, which together do the thermal work.

Container and closure, since the process is validated against them.

And frequently particle size or viscosity, because both affect how quickly acid penetrates solids and therefore how long equilibrium takes.

Why they are limits rather than targets

A critical factor usually defines a boundary: pH no higher than, fill temperature no lower than, hold time no shorter than.

Which means running comfortably inside them is free and running at them is not. Producers who target the limit have no margin for a meter drifting, a warm room or a slow filling run.

Monitoring them

Every batch, recorded at the time, against the written values. A fill temperature checked once at the start of a run is not a monitored critical factor if the run takes an hour.

Build the batch record around the critical factors rather than around the recipe, so that the document you fill in is the document that demonstrates compliance.

References