Cleaning down between batches

In a craft with no kill step, the cleanliness of the equipment is part of the product specification. This is the least glamorous page here and one of the most consequential.

Why this is not housekeeping

Every surface the product touches after the phases are combined is a route for contamination, and there is no later step that removes what gets in. The challenge test assumes a product that started clean; it does not create one.

Manufacturing hygiene is one of the three routes contamination arrives by, alongside raw materials and the customer, and it is the only one entirely within your control.

Residue is an inoculum

Product left in a mixer, a funnel or a filling line is warm, nutrient-rich and no longer protected by a preservative doing its job in a sealed container. It grows, and the next batch through inherits it.

The dangerous residue is the invisible kind: a film in a pump body, product behind a gasket, a thread on a nozzle. Those places are where a small operation's contamination problems actually live.

The sequence that works

Dismantle rather than rinse through. Anything that comes apart should come apart, because the parts that do not get taken apart are the parts that never get clean.

Then: remove the product physically, wash with a detergent, rinse, sanitize with an appropriate agent at its required contact time, and dry. Contact time is the step people shorten and it is the step that does the work.

Water is the last thing

Water left in equipment is a growth medium, and a sanitized-but-wet vessel is not a clean vessel by the following morning. Dry properly, store covered, and sanitize again before use if anything has been standing.

The same applies to containers. Jars and pumps arrive clean enough for most purposes and not sterile, and for a product whose preservation margin is thin it is worth knowing which your supplier is selling you.

References