Brewery CIP: How To Check That Your Caustic Is Properly Rinsed

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Cleaning is a big part of brewing, and to fail to do it effectively can result in poor quality beer. There’s just no getting around it.

As you know, caustic is an excellent ingredient for cleaning your Brewhouse, but rinsing it out can be a real nightmare.

If you don’t rinse the caustic effectively from your brewhouse, it can wind up in your next batch of beer. It can change your mash and/or wort pH readings, which in turn affects the efficiency of the brewing process and alters the flavor of the final beer.

The cleaning itself is actually pretty simple. All you have to do is send the caustic to all the different pathways in a brewhouse to make sure that you’re cleaning it very well. The real tricky part lies in rinsing because you’re unable to see the caustic while it’s being rinsed.

Now, there are different ways in which you can get rid of caustic out of your brewhouse, but today, we’ll be focusing on the use of water since it’s what we mainly use in breweries.
It’s really common for wineries to use something like citric acid to neutralise the caustic and get it out of their system, but we tend not to do that in breweries. I don’t see a problem with it, though, just as long as rinsing is done accordingly.

Rinsing Caustic with Water

It usually takes a lot of water to flush all of the caustic out of your system.

What we need to keep an eye out for are “dead legs”.

A dead leg is used to describe a run of pipework that doesn’t maintain a regular flow of water.

Thus, your rinse water might be going in one direction, but there’s that little leg off to the side that doesn’t get that direct flow.

Dead legs experience periods of little to no fluid circulation which can lead to pockets of caustic remaining in your Brewhouse that are not cleaned properly.

This can lead to growth of other potentially harmful bacteria that can cause off-flavours in your beer if overlooked.

You need to make sure that you’re rinsing along the main pathway while simultaneously sending enough water up into each secondary pathway to ensure that the dead legs also get a proper rinse.

How to Ensure Your Brewhouse is Sufficiently Rinsed of Caustic

Once common mistake that brewers make in checking if their caustic is rinsed well is by touching the rinse water with their fingers to look for a slippery feeling.

There are two problems in doing it this way:

First, getting caustic on your skin can cause irritation and even burns; and second, that slippery sensation is simply caused by a chemical process called saponification, which happens when the sodium hydroxide in your caustic solution turns the fats in your skin into soap whenever you touch it.

Meaning, this is really not an accurate nor safe way to check if your caustic is rinsed!

The right tool to use in ensuring that your brewhouse is properly rinsed is an organic compound called “Phenolphthalein.”

It’s a colourless, weak acid that is widely used as a laboratory reagent and pH indicator. How it works is that if the pH of the rinse fluid or anything that it touches is above around 8.2, it turns into a pinkish, purplish colour.

Before trying it out for yourself, make sure to wear safety gloves. Here’s how you use Phenolphthalein to check if your caustic is rinsed.

⦁ Grab a plastic jug and wash it several times to make sure it’s not contaminated with your previous sample.
⦁ Fill the plastic jug with a sample of the rinse water.
⦁ Put a couple of drops of phenolphthalein in the plastic jug. If the rinse water turns pink, it means that caustic is still present and you need to keep rinsing. It’s also possible that there are dead legs that require more rinsing. On the other hand, if the rinse water comes up clear, you’re all good.

Here’s what rinse water looks like compared to one that still has caustic in it when dosed with Phenolphthalein:

Essentially, what Phenolphthalein does is it confirms whether or not you’ve adequately rinsed all the dead legs in your brewhouse, leaving your equipment in clean and pristine condition, ready to make awesome beer.

You don’t want caustic in your beer. So get out there, my fellow brewers, and rinse that caustic!

If you want some more awesome content, be sure to check out my free training at https://rockstarbrewer.com/freetraining.

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