Hello again N.E.W. Ales readers! Going off the stats from my last blog post, it seems like everyone loves them some science topics. I figured we would branch off my last post about passivation of stainless steel and focus on the cleaning of that same steel this week. I want to give a brief (ish) overview on different cleaning methods, chemicals, and issues we run into when trying to clean up the mess left over from any process in a beverage factory.
Let’s start off by talking about the two major methods of cleaning in any food factory across the US. The first of which is a manual process, this includes breaking out the scrub brushes and chemical foamers (yes, they shoot chemical foam that sticks to equipment, and yes, they are fun to play with) to clean any surface on a production line. The other major method of cleaning in a beverage factory is CIP/COP. CIP (Clean in Place) is a process used when your tank or piping can’t be easily disassembled to clean. Instead we rely on temperature, spray devices, and chemicals, to clean hard to reach areas that would otherwise be impossible. COP (Clean Out of Place) is a very similar process except large parts that can be removed instead go into a tank to be cleaned by relying on temperature, chemicals, and spray jets, while the parts are submerged in the tank. Most of the time, beverage factories use a lot of CIP while food factories use manual cleaning and COP.
I’m not going to go over manual cleaning in this post, but we will talk about CIP, which is most of what a brewery uses to clean tanks. If you want to have a good CIP process, then you need to pay attention to the five T’s--Temperature, Turbidity, Technology, Time, and Titration.
Temperature is important for solubility. Water that is hot can dissolve and absorb more material than cold water. For a caustic wash, you want a minimum of 140F, while acids can be ran a bit cooler at 110-120F. Water that is too hot or cold can be ineffective, so always look at your chemical label to see the recommended range.
Turbidity is referring to the flow of your cleaning solution. If you look at a slow-moving creek, the rocks will all have moss on them. An area of the same creek with rapids will have clean rocks. The same principle applies to the cleaning process. We want to target five feet per second of flow rate to clean the inside of your pipes. A simple calculator can be found online to discover your flow rate when looking at flow rate in gallons per minute (GPM), and pipe size.
Technology is referring to the clean-ability of your system and cleaning devices used. No amount of temperature or turbid water flow will overcome obvious design flaws in your pipe. Bad welds, poor valve seals, leaking pumps, or even poor placement of sensors can all lead to issues with the CIP process. The cleaning devices used is important for the type of spray devices used inside of a tank. I can go on for days about the hygienic design of sanitary piping, but might save that topic for another day.
Time is somewhat self-explanatory. Your chemical washes should be long enough to clean, but short enough to minimize line downtime. I will, however, argue that instead of looking at the time of your wash cycles, the time of rinse steps are almost more important. A dirty tank is not nearly as bad as chemical not being fully rinsed out of a tank and losing a batch of product due to chemical contamination--a serious food safety issue.
Titration is referring to the type of chemical and amount used. Think about dish detergent that’s by your kitchen sink right now. Chances are it has a pretty high pH, which is good for removing grease and other types of organic materials that you would find when you were cooking. These high pH chemicals, also called caustic chemicals, are the bread and butter of the beverage industry. Almost all of what you need to clean off of stainless steel will be organic buildup, whether it’s protein rings in a fermenter, or biofilm buildup inside a water pipe. Therefore it is pretty clear we tend to use a lot of caustic.
The other end of the spectrum is acidic chemicals. These are chemicals very low on the pH scale. They’re not good at cleaning organic buildup, but they are very good at removing mineral deposits. Something like hard water buildup on the inside of a hot liquor tank, or boil kettle, can be easily removed with an acid cleaner. For this example, think of a bottle of CLR. It’s good at removing calcium lime and rust buildup from a sink or shower head because it’s an acidic cleaner.
If you try to clean calcium buildup with a caustic chemical, it won’t work. If you try to clean some fat or protein buildup off a surface with an acid cleaner, you’re wasting your time. So, the first in a good clean is understanding the chemicals needed to get the desired results. If you can keep your five T’s in range, then your CIP will be successful.
The last bit I want to touch on before moving on to some funny(ish) stories is what order to clean. I will share the basic overview of my processes with some of the T’s outlined.
If you’re doing a caustic only wash, then you will be doing a 4-5 step CIP depending on the type of sanitizer used. Step 1 is a pre-rinse with hot water. This step is arguably the most important because the more junk you can rinse out of your tanks and pipes before moving on will make the next steps run faster with more efficiency. Step 2 is your caustic wash. I like to run about 4% caustic by volume for 40 minutes at 140F
minimum. Step 3 is another rinse to remove the caustic chemical. Then step 4 will be a sanitizer. If you’re using a no rinse sanitizer like Peracetic Acid (PAA)/ Hydrogen Peroxide then no step 5 is needed, otherwise the 5th step is another rinse to remove the sanitizer. I like to use PAA at ~ 4oz per gallon of water and run that for about 5 minutes at room temperature.
Now that everyone has a basic understanding of CIP and how it should be performed, I can share some personal stories I have experienced with past employers. My favorite story by far is an important lesson in temperature. When you throw hot water at a tank, the gas inside the tank will expand and build up pressure. The opposite is also true about throwing cold water at a hot tank. The tank’s gas inside will contract to take up less space. Always have your tank vented when performing a CIP. Why you ask? Well, if your tank is closed up after a CIP, and is still hot, then a batching tech adds cold water to the tank, the air inside will turn cold, contract, and literally suck the tank in.
This exact same thing happened to me with a 9000-gallon horizontal tank. The tech called me to the floor, and I did manage to fix the tank by cooling it down, then pushing hot water to increase the pressure and pop the tank back out. However, the moral of the story is always vent your tank when cleaning. I didn’t get a picture of that incident, but this is one that happened to the guy that trained me. You can tell, a very expensive mistake to make.
My next story comes from a dairy plant. It has to-do with chemical concentration and why more is not always better. In this case the operators thought more chemical would clean their pipes more efficiently. However, the high concentration actually baked the milk proteins and caused a film to form. You can actually see in the picture below (cross section of a pipe) that they kept performing the same CIP between production runs until the flow to their filler was almost gone due to baking on what the CIP was supposed to remove.
The moral of the story is always pay attention to the five T’s! Also, look into what you cleaned to make sure the process was a success. This is just the tip of a very large iceberg, so if you want me to elaborate on a certain topic or want to pitch me an idea of a future post feel free to leave a comment or reach out on social media.
Until next time.